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Small Size (small + size)
Kinds of Small Size Selected AbstractsPeak Bone Mass After Exposure to Antenatal Betamethasone and Prematurity: Follow-up of a Randomized Controlled Trial,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2006Stuart R Dalziel Abstract Small birth size is associated with reduced adult bone mass. We determined if antenatal betamethasone exposure, birth weight, or prematurity affects peak bone mass in 174 adults. Antenatal betamethasone exposure did not. Lower birth weight and prematurity predicted reduced adult height. Slower fetal growth rather than prematurity predicted lower bone mass, but this lower bone mass was appropriate for reduced adult height. Introduction: Small size at birth is reported to be associated with lower bone mass in adulthood. However, previous studies have not distinguished the relative contributions of length of gestation and fetal growth to size at birth. Fetal exposure to excess glucocorticoids has been proposed as a core mechanism underlying the associations between birth size and later disease risk. Antenatal glucocorticoids are given to pregnant women at risk for preterm delivery for the prevention of neonatal respiratory distress syndrome in their infants. We determined the relationship of antenatal exposure to betamethasone, birth weight, and prematurity to peak bone mass and femoral geometry in the adult survivors of the first randomized trial of antenatal glucocorticoids. Materials and Methods: We studied 174 young adults (mean age, 31 years) whose mothers participated in a randomized trial of antenatal betamethasone. Mothers received two doses of intramuscular betamethasone or placebo 24 h apart. Two thirds of participants were born preterm (<37 weeks gestation). We measured indices of bone mass and size and derived estimates of volumetric density and bone geometry from DXA assessments of the lumbar spine, femur, and total body. Results: There were no differences between betamethasone-exposed and placebo-exposed groups in any of the lumbar spine, femur, or total body DXA measures. There was no effect of antenatal betamethasone on adult height, although leg length was increased relative to trunk length (p = 0.002). A lighter birth weight (p , 0.001) and lower gestational age (p = 0.013) were associated with shorter stature (height Z scores) at age 31 years. Prematurity had no effect on peak bone mass or femoral geometry. However, lower birth weight, independent of gestational age, was associated with lower later bone mass (p < 0.001 for lumbar spine and total body, p = 0.003 for femoral neck BMC). These effects on bone mass were related to bone size and not to estimates of volumetric density. In the femur, lower birth weight, independent of gestational age, was associated with narrowing of the upper shaft and narrow neck regions. Conclusions: Antenatal betamethasone exposure does not affect peak bone mass or femoral geometry in adulthood. Birth weight and prematurity predict adult height, but it is slower fetal growth, rather than prematurity, that predicts lower peak bone mass. The lower peak bone mass in those born small is appropriate for their adult height. [source] Small size and disease severity in living donation: A difficult match,LIVER TRANSPLANTATION, Issue 5 2009Kim M. Olthoff [source] Competition as a selective mechanism for larger offspring size in guppiesOIKOS, Issue 1 2008Farrah Bashey Highly competitive environments are predicted to select for larger offspring. Guppies Poecilia reticulata from low-predation populations have evolved to make fewer, larger offspring than their counterparts from high-predation populations. As predation co-varies with the strength of competition in natural guppy populations, here I present two laboratory experiments that evaluate the role of competition in selecting for larger offspring size. In the first experiment, paired groups of large and small newborns from either a high- or a low-predation population were reared in mesocosms under a high- or a low-competition treatment. While large newborns retained their size advantage over small newborns in both treatments, newborn size increased growth only in the high-competition treatment. Moreover, the increase in growth with size was greater in guppies derived from the low-predation population. In the second experiment, pairs of large and small newborns were reared in a highly competitive environment until reproductive maturity. Small size at birth delayed maturation and the effect of birth size on male age of maturity was greater in the low-predation population. These results support the importance of competition as a selective mechanism in offspring size evolution. [source] Childhood malnutrition and its predictors in rural MalawiPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 4 2003Kenneth Maleta Summary We prospectively followed up a population-based cohort of 767 rural Malawian children from birth to 36 months to characterise the timing and predictors of malnutrition. Underweight and wasting incidence peaked between 6 and 18 months of age, whereas stunting incidence was highest during the first 6 months of age. After infancy about 40% of the children were underweight, 70% stunted, and about 4% wasted. Small size during the first 3 months of life predicted the incidence of severe underweight (relative risk [95% confidence interval], 1.8 [0.9, 3.4]), severe stunting ( 2.1 [1.3, 3.4]), and moderate wasting (2.0 [1.1, 3.5]). Children with many illness episodes in infancy had a twofold risk for the development of severe underweight and moderate wasting. Severe underweight was further predicted by residence far away from a health facility and moderate wasting by maternal HIV infection. Our conclusion is that the intrauterine period and first 6 months of life are critical for the development of stunting whereas the subsequent year is more critical for the development of underweight and wasting. Strategies combating intrauterine growth retardation, maternal HIV and infant morbidity are likely to reduce the burden of malnutrition in this population. [source] Extended Mechanical Circulatory Support With a Continuous-Flow Rotary Left Ventricular Assist DeviceCONGESTIVE HEART FAILURE, Issue 2 2010Scott Harris DO Background LVAD therapy is an established treatment modality for patients with advanced heart failure. Pulsatile LVADs have limitations in design precluding their use for extended support. Continuous-flow rotary LVADs represent an innovative design with potential for small size and greater reliability by simplification of the pumping mechanism. Methods In a prospective multicenter study, 281 patients urgently listed (United Network for Organ Sharing status 1A or 1B) for heart transplant underwent implant of a continuous-flow LVAD. Survival and transplant rates were assessed at 18 months. Patients were assessed for adverse events throughout the study and for quality of life, functional status, and organ function for 6 months. Results Of 281 patients, 222 (79%) underwent transplant or LVAD removal for cardiac recovery or had ongoing LVAD support at 18-month follow-up. Actuarial survival on support was 72% (95% confidence interval, 65%,79%) at 18 months. At 6 months, there were significant improvements in functional status and 6-minute walk test results (from 0% to 83% of patients in New York Heart Association functional class I or II and from 13% to 89% of patients completing a 6-minute walk test) and in quality of life (mean values improved 41% with Minnesota Living With Heart Failure and 75% with Kansas City Cardiomyopathy questionnaires). Major adverse events included bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in 4 patients. Conclusions A continuous-flow LVAD provides effective hemodynamic support for at least 18 months in patients awaiting transplant, with improved functional status and quality of life. [source] The Contribution of Long-Term Research at Gombe National Park to Chimpanzee ConservationCONSERVATION BIOLOGY, Issue 3 2007ANNE E. PUSEY chimpancé; conservación de simios mayores; Parque Nacional Gombe; Tanzania Abstract:,Long-term research projects can provide important conservation benefits, not only through research specifically focused on conservation problems, but also from various incidental benefits, such as increased intensity of monitoring and building support for the protection of an area. At Gombe National Park, Tanzania, long-term research has provided at least four distinct benefits to wildlife conservation. (1) Jane Goodall's groundbreaking discoveries of chimpanzee (Pan troglodytes) tool use, hunting, and complex social relationships in what was then a game reserve drew attention to the area and created support for upgrading Gombe to national park status in 1968. (2) The highly publicized findings have earned Gombe and Tanzania the attention of a worldwide public that includes tourists and donors that provide financial support for Gombe, other parks in Tanzania, and chimpanzee conservation in general. (3) Crucial information on social structure and habitat use has been gathered that is essential for effective conservation of chimpanzees at Gombe and elsewhere. (4) A clear picture of Gombe's chimpanzee population over the past 40 years has been determined, and this has helped identify the greatest threats to the viability of this population, namely disease and habita loss outside the park. These threats are severe and because of the small size of the population it is extremely vulnerable. Research at Gombe has led to the establishment of conservation education and development projects around Gombe, which are needed to build local support for the park and its chimpanzees, but saving these famous chimpanzees will take a larger integrated effort on the part of park managers, researchers, and the local community with financial help from international donors. Resumen:,Los proyectos de investigación de largo plazo pueden proporcionar beneficios importantes a la conservación, no solo a través de investigación enfocada específicamente a problemas de conservación, sino también a través de varios beneficios incidentales, como una mayor intensidad de monitoreo y construcción de soporte para la protección de un área. En el Parque Nacional Gombe, Tanzania, la investigación a largo plazo ha proporcionado por lo menos cuatro beneficios a la conservación de vida silvestre. (1) Los descubrimientos innovadores de Jane Goodall sobre el uso de herramientas, la cacería y las complejas relaciones sociales de chimpancés en lo que entonces era una reserva de caza atrajeron la atención al área y crearon el soporte para cambiar a Gombe a estatus de parque nacional en 1968. (2) Los hallazgos muy publicitados han ganado para Gombe y Tanzania la atención del público en todo el mundo incluyendo turistas y donadores que proporcionan soporte financiero a Gombe, otros parques en Tanzania y a la conservación de chimpancés en general. (3) Se ha reunido información crucial sobre la estructura social y el uso del hábitat que ha sido esencial para la conservación efectiva de chimpancés en Gombe y otros sitios. (4) Se ha determinado un panorama claro de la población de chimpancés en Gombe durante los últimos 40 años, y esto a ayudado a identificar las mayores amenazas a la viabilidad de esta población, a saber enfermedades y pérdida de hábitat fuera del parque. Estas amenazas son severas y la población es extremadamente vulnerable por su tamaño pequeño. La investigación en Gombe ha llevado al establecimiento de proyectos de desarrollo y de educación para la conservación en los alrededores del parque, lo cual es necesario para encontrar soporte local para el parque y sus chimpancés, pero el rescate de estos famosos chimpancés requerirá de un esfuerzo más integrado de parte de los manejadores del parque, investigadores y la comunidad local con la ayuda financiera de donadores internacionales. [source] NON-GYNAECOLOGICAL CYTOLOGY: THE CLINICIAN'S VIEWCYTOPATHOLOGY, Issue 2006I. Penman There is increased recognition of the importance of accurate staging of malignancies of the GI tract and lung, greater use of neoadjuvant therapies and more protocol-driven management. This is particularly important where regional lymph node involvement significantly impacts on curability. Multidetector CT and PET scanning have resulted in greater detection of potential abnormalities which, if positive for malignancy, would change management. There is also a greater recognition that many enlarged nodes may be inflammatory and that size criteria alone are unreliable in determining involvement. In other situations, especially pancreatic masses, not all represent carcinoma as focal chronic pancreatitis, autoimmune pancreatitis etc can catch out the unwary. A preoperative tissue diagnosis is essential and even if unresectable, oncologists are increasingly reluctant to initiate chemotherapy or enroll patients into trials without this. The approach to obtaining tissue is often hampered by the small size or relative inaccessibility of lesions by percutaneous approaches. As such novel techniques such as endoscopic ultrasound (EUS) guided FNA have been developed. A 120cm needle is passed through the instrument and, under real-time visualisation, through the gastrointestinal wall to sample adjacent lymph nodes or masses. Multiple studies have demonstrated the safety and performance of this technique. In oesophageal cancer, confirmation of node positivity by has a major negative influence on curative resection rates and will often lead to a decision to use neoadjuvant chemotherapy or a non-operative approach. Sampling of lymph nodes at the true coeliac axis upstages the patient to M1a status (stage IV) disease and makes the patient incurable. In NSCLC, subcarinal lymph nodes are frequently present but may be inflammatory. If positive these represent N2 (stage IIIA) disease and in most centres again makes the patient inoperable. Access to these lymph nodes would otherwise require mediastinosocopy whereas this can be done simply, safely and quickly by EUS. Overall the sensitivity for EUS , FNA of mediastinal or upper abdominal lymph nodes is 83,90% with an accuracy of 80,90%. In pancreatic cancer performance is less good but pooled analysis of published studies indicates a sensitivity of 85% and accuracy of 88%. In a recent spin-off from EUS, endobronchial ultrasound (EBUS) instruments have been developed and the ability to sample anterior mediastinal nodes has been demonstrated. It is likely that this EBUS , FNA technique will become increasingly utilised and may replace mediastinoscopy. The development of techniques such as EUS and EBUS to allow FNA sampling of lesions has increased the role of non-gynaecological cytology significantly in recent years. Cytology therefore remains important for a broad range of specialties and there is ongoing need for careful and close co-operation between cytologists and clinicians in these specialties. References:, 1. Williams DB, Sahai AV, Aabakken L, Penman ID, van Velse A, Webb J et al. Endoscopic ultrasound guided fine needle aspiration biopsy: a large single centre experience. Gut. 1999; 44: 720,6. 2. Silvestri GA, Hoffman BJ, Bhutani MS et al. Endoscopic ultrasound with fine-needle aspiration in the diagnosis and staging of lung cancer. Ann Thorac Surg 1996; 61: 1441,6. 3. Rintoul RC, Skwarski KM, Murchison JT, Wallace WA, Walker WS, Penman ID. Endobronchial and endoscopic ultrasound real-time fine-needle aspiration staging of the mediastinum ). Eur Resp J 2005; 25: 1,6. [source] Determinants for the successful establishment of exotic ants in New ZealandDIVERSITY AND DISTRIBUTIONS, Issue 4 2005Philip J. Lester ABSTRACT Biological invasions can dramatically alter ecosystems. An ability to predict the establishment success for exotic species is important for biosecurity and conservation purposes. I examine the exotic New Zealand ant fauna for characteristics that predict or determine an exotic species' ability to establish. Quarantine records show interceptions of 66 ant species: 17 of which have established, 43 have failed to establish, whereas nests of another six are periodically observed but have failed to establish permanently (called ,ephemeral' establishment). Mean temperature at the highest latitude and interception variables were the only factors significantly different between established, failed or ephemeral groups. Aspects of life history, such as competitive behaviour and morphology, were not different between groups. However, in a stepwise discriminant analysis, small size was a key factor influencing establishment success. Interception rate and climate were also secondarily important. The resulting classification table predicted establishment success with 71% accuracy. Because not all exotic species are represented in quarantine records, a further discriminant model is described without interception data. Though with less accuracy (65%) than the full model, it still correctly predicted the success or failure of four species not used in the previous analysis. Techniques for improving the prediction accuracy are discussed. Predicting which species will establish in a new area appears an achievable goal, which will be a valuable tool for conservation biology. [source] Echocardiographic Evaluation of Ventricular Function in MiceECHOCARDIOGRAPHY, Issue 1 2007Jeffrey N. Rottman M.D. Ventricular dysfunction remains a hallmark of most cardiac disease. The mouse has become an essential model system for cardiovascular biology, and echocardiography an established tool in the study of normal and genetically altered mice. This review describes the measurement of ventricular function, most often left ventricular function, by echocardiographic methods in mice. Technical limitations related to the small size and rapid heart rate in the mouse initially argued for the performance of echocardiography under anesthesia. More recently, higher frame rates and smaller probes operating at higher frequencies have facilitated imaging of conscious mice in some, but not all, experimental protocols and conditions. Ventricular function may be qualitatively and quantitatively evaluated under both conditions. Particular detail is provided for measurement under conscious conditions, and measurement under conscious and sedated or anesthestized conditions are contrasted. Normal values for echocardiographic indices for the common C57BL/6 strain are provided. Diastolic dysfunction is a critical pathophysiologic component of many disease states, and progress in the echocardiographic evaluation of diastolic function is discussed. Finally, echocardiography exists among several competing imaging technologies, and these alternatives are compared. [source] Distribution, zoogeography and biology of the Murchison River hardyhead (Craterocephalus cuneiceps Whitley, 1944), an atherinid endemic to the Indian Ocean (Pilbara) Drainage Division of Western AustraliaECOLOGY OF FRESHWATER FISH, Issue 3 2005M. G. Allen Abstract , The Murchison River hardyhead (Craterocephalus cuneiceps) is endemic to the extremely arid Indian Ocean (Pilbara) Drainage Division of Western Australia, where it is found in the Greenough, Hutt, Murchison, Wooramel, Gascoyne and DeGrey rivers, but is absent from numerous rivers within its range. The most likely explanation for the disjunct contemporary distribution is that C. cuneiceps has simply never inhabited the rivers from which it is conspicuously absent (e.g. Ashburton and Fortescue). Biogeographical, geological and palaeoclimatic evidence is presented to support this hypothesis. In the Murchison River, breeding was extremely protracted with recruitment occurring throughout the year. The largest female and male specimens captured were 96 mm total length (TL; 7.73 g) and 86 mm TL (5.57 g), respectively. Sex ratio was 1.09 females:1 male. Batch fecundity ranged from 46 to 454 (mean 167.5 ± 25.7 SE). Estimates for the length at which 50 and 95% of females first spawned were 36.4 and 44.3 mm TL, respectively. Craterocephalus cuneiceps is essentially a detritivore, but also feeds on aquatic invertebrates. Rainfall in the Murchison River catchment is unpredictable and pH, salinity and temperature are variable. A specialised diet, small size and young age at maturity and protracted spawning period, coupled with serial spawning and high fecundity, allows the numerical dominance of this species in competitive, harsh, arid and unpredictable desert environments. Resumen 1. Craterocephalus cuneiceps es una especie endémica de las cuencas del Océano Indico (i.e., Pilbara) de Australia Occidental. Se encuentra en los ríos Greenough, Hutt, Murchison, Wooramel, Gascoyne y DeGrey pero está ausente en numerosos ríos dentro de su área de distribución. La explicación más probable para esta distribución separada en la actualidad es que C. cuneiceps no ha habitado nunca los ríos en los que está ausente tales como los ríos Ashburton y Fortescue. Presentamos evidencia bio-geográfica, geológica y paleo-climática para soportar esta hipótesis. 2. En el río Murchison, la reproducción es extremadamente prolongada con reclutamiento a lo largo de todo el año. Los mayores machos y hembras capturados alcanzaron 96 mm LT (7.73 g) y 86 mm LT (5.57 g), respectivamente. La proporción de sexos fue 1.09 hembras: 1 macho. La fecundidad varió entre 46 y 454 (media 167.5 ± 25.7 SE) y la longitudes a la que el 50 y el 95% de las hembras se reproducen por primera vez alcanzaron 36.4 y 44.3 mm LT, respectivamente. 3. C. cuneiceps es esencialmente detritívoro pero también se alimenta de invertebrados acuáticos. La lluvia sobre la cuenca del río Murchison es impredecible y el pH, la salinidad y la temperatura son variables. Una dieta especializada, pequeño tamaño, una edad joven en la madurez, y un período reproductivo prolongado, ademos de una freza seriada y alta fecundidad, permiten la dominancia numérica de la especie en ambientes competitivos, duros, áridos e impredecibles. [source] Analysis of the effects of ultrafine particulate matter while accounting for human exposureENVIRONMETRICS, Issue 2 2009B. J. REICH Abstract Particulate matter (PM) has been associated with mortality in several epidemiological studies. The US EPA currently regulates PM10 and PM2.5 (mass concentration of particles with diameter less than 10 and 2.5 µm, respectively), but it is not clear which size of particles are most responsible for adverse heath outcomes. A current hypothesis is that ultrafine particles with diameter less than 0.1 µm are particularly harmful because their small size allows them to deeply penetrate the lungs. This paper investigates the association between exposure to particles of varying diameter and daily mortality. We propose a new dynamic factor analysis model to relate the ambient concentrations of several sizes of particles with diameters ranging from 0.01 to 0.40 µm with mortality. We introduce a Bayesian model that converts ambient concentrations into simulated personal exposure using the EPA's Stochastic Human Exposure and Dose Simulator, and relates simulated exposure with mortality. Using new data from Fresno, CA, we find that the 4-day lag of particles with diameter between 0.02 and 0.08 µm is associated with mortality. This is consistent with the small particles hypothesis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Efficacy screening trials of paroxetine, pentoxifylline, riluzole, pramipexole and venlafaxine in cocaine dependenceADDICTION, Issue 2005Domenic A. Ciraulo ABSTRACT Aims The two studies presented here were conducted to assess the efficacy of paroxetine, pentoxifylline, riluzole, venlafaxine and pramipexole as medications for the treatment of cocaine dependence. Design A multi-arm, modified blinded, placebo-controlled design was used. Setting The studies were conducted at the Boston VA Healthcare System and the Boston University School of Medicine Medication Development Research Unit (MDRU). Participants Participants met criteria for cocaine dependence during a 2-week screening period. Intervention Following random assignment to one of the treatment groups, subjects received active medication or placebo for 8 weeks in combination with cognitive behavioral counseling. In the first study the efficacy of the antidepressant paroxetine (20 mg daily), the phosphodiesterase inhibitor pentoxifylline (1200 mg daily) and the glutamate release inhibitor riluzole (100 mg daily) was assessed. The antidepressant venlafaxine (150 mg daily) and the dopamine agonist pramipexole (1.5 mg daily) were evaluated in the second study. Measurements Urine benzoylecgonine (BE) concentrations, self-report of cocaine use and global impression scores served as primary outcome measures. Secondary measures included assessments of cocaine craving and psychiatric functioning. Adverse events were monitored during the treatment period. Findings None of the active medications produced greater reductions in urine BE concentrations over the treatment period than did placebo. There were trends for BE levels to become reduced in the pentoxifylline group during the first 4 weeks of treatment and for Addiction Severity Index (ASI) drug composite scores to be lower in the pentoxyfylline group at end-point compared to the placebo group. Significant within-group reductions in reported cocaine use and craving were found for all treatment groups, but none of the active medications were superior to placebo on these measures. The accuracy of self-reported cocaine use declined over the study period. Overall, the active medications were well tolerated. Conclusions This study does not support the use of paroxetine, pentoxifylline, riluzole, venlafaxine or pramipexole for the treatment of cocaine dependence. However, these results need to be interpreted with caution because of the small size and lack of homogeneity of the experimental groups. [source] In vivo voltammetric monitoring of norepinephrine release in the rat ventral bed nucleus of the stria terminalis and anteroventral thalamic nucleusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2009Jinwoo Park Abstract The role and contribution of the dense noradrenergic innervation in the ventral bed nucleus of the stria terminalis (vBNST) and anteroventral thalamic nucleus (AV) to biological function and animal behaviors is poorly understood due to the small size of these nuclei. The aim of this study was to compare norepinephrine release and uptake in the vBNST with that in the AV of anesthetized rats. Measurements were made in vivo with fast-scan cyclic voltammetry following electrical stimulation of noradrenergic projection pathways, either the dorsal noradrenergic bundle (DNB) or the ventral noradrenergic bundle (VNB). The substance detected was identified as norepinephrine based upon voltammetric, anatomical, neurochemical and pharmacological evidence. Fast-scan cyclic voltammetry enables the selective monitoring of local norepinephrine overflow in the vBNST evoked by the stimulation of either the DNB or the VNB while norepinephrine in the AV was only evoked by DNB stimulation. The ,2-adrenoceptor antagonist yohimbine and the norepinephrine uptake inhibitor desipramine increased norepinephrine overflow and slowed its disappearance in both regions. However, control of extracellular norepinephrine by both autoreceptors and uptake was greater in the AV. The greater control exerted by autoreceptors and uptake in the AV resulted in reduced extracellular concentration compared with the v,BNST when large numbers of stimulation pulses were employed. The differences in noradrenergic transmission observed in the terminal fields of the v,BNST and the AV may differentially regulate activity in these two regions that both contain high densities of norepinephrine terminals. [source] Automated diffusion chambers to monitor diurnal and seasonal dynamics of the soil CO2 concentration profileEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2009F. Albanito Summary To better understand the factors controlling carbon dioxide (CO2) production and transport in soil, we developed a new method to continuously monitor soil CO2 concentration at multiple depths, by using diffusion chambers. The soil diffusion chambers are constructed from a high-density polyethylene cylindrical frame enclosed by a micro-polyvinylidene difluoride flat membrane (PVDF). All chambers are linked to an infrared gas analyser positioned above-ground through a multi-port valve system. We set up two experimental sites for long-term measurements of soil CO2 concentration, soil temperature and soil water content at depths of 0, 10, 20, 40 and 80 cm. The system provides the following advantages : (i) the use of the PVDF combined with the small dimensions of the diffusion chambers allows rapid diffusion of soil gas into the chambers and therefore a short equilibration time of the gas phase with the surrounding soil atmosphere, (ii) the equilibrating closed loop system allows the semi-continuous measurement of soil profile CO2 concentrations without creating a pressure differential within the chambers, thus reducing gas concentration distortions in the soil, (iii) the small size of the closed diffusion chambers reduces the initial soil disturbance during installation, (iv) it allows sampling in wet, humid soils, including ones that are waterlogged or temporarily saturated, and (v) the chambers do not require removal for maintenance purposes and are inexpensive. [source] Surface-Protected Etching of Mesoporous Oxide Shells for the Stabilization of Metal NanocatalystsADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Qiao Zhang Abstract Nanoparticles of transition metals, particularly noble metals, are widely used in catalysis. However, enhancing their stability during catalytic reactions has been a challenge that has limited the full use of the benefits associated with their small size. In this Feature Article, a general "encapsulation and etching" strategy for the fabrication of nanocatalyst systems is introduced in which catalyst nanoparticles are protected within porous shells. The novelty of this approach lies in the use of chemical etching to assist the creation of mesopores in a protective oxide shell to promote efficient mass transfer to encapsulated metal nanoparticles. The etching process allows for the direct transformation of dense silica coatings into porous shells so that chemical species can reach the catalyst surface to participate in reactions while the shells act as physical barriers against aggregation of the catalyst particles. By using the surface-protected etching process, both yolk,shell and core,satellite type nanoreactors are synthesized and their utilization in liquid- and gas-phase catalysis is demonstrated. The thermal and chemical stability of the metallic cores during catalytic reactions is also investigated, and further work is carried out to enhance recyclability via the introduction of superparamagnetic components into the nanoreactor framework. [source] Curvature properties of novel forms of phosphatidylcholine with branched acyl chainsFEBS JOURNAL, Issue 10 2000Richard M. Epand We studied the properties of a series of phosphatidylcholine molecules with branched acyl chains. These lipids have previously been shown to have marked stimulatory effects on the side-chain cleavage activity of cytochrome P450SCC (CYP11A1), an enzyme of the inner mitochondrial membrane. The synthetic lipids used were diacyl phosphatidylcholines with the decanoyl, dodecanoyl or tetradecanoyl chain having a hexyl, octyl or decyl straight chain aliphatic branch at the 2-position. All three lipids lowered the bilayer to hexagonal phase transition temperature of dielaidoyl phosphatidylethanolamine, the lipids with longer acyl chains being more effective in this regard. As pure lipids all of the forms were found by X-ray diffraction to be predominantly in the hexagonal phase (HII) over the entire temperature range of 7,75 °C. The properties of the HII phase were unusual with regard to the small size of the lattice spacings and the small temperature dependence of the spacings. We used tetradecane to relieve hydrocarbon packing constraints to determine the intrinsic radius of curvature of the lipid monolayer. The elastic bending modulus was measured in the presence of tetradecane by introducing an osmotic gradient across the hexagonal phase cylinders with aqueous solutions of poly(ethylene glycol). The elastic bending modulus was found to be higher than that observed with other lipids and to increase with temperature. Both the small intrinsic radius of curvature and the high elastic bending modulus indicate that the presence of these lipids in bilayer membranes will impose a high degree of negative curvature strain. [source] The mitochondrial genome of the wine yeast Hanseniaspora uvarum: a unique genome organization among yeast/fungal counterpartsFEMS YEAST RESEARCH, Issue 1 2006Paraskevi V. Pramateftaki Abstract The complete sequence of the apiculate wine yeast Hanseniaspora uvarum mtDNA has been determined and analysed. It is an extremely compact linear molecule containing the shortest functional region ever found in fungi (11 094 bp long), flanked by Type 2 telomeric inverted repeats. The latter contained a 2704-bp-long subterminal region and tandem repeats of 839-bp units. In consequence, a population of mtDNA molecules that differed at the number of their telomeric reiterations was detected. The functional region of the mitochondrial genome coded for 32 genes, which included seven subunits of respiratory complexes and ATP synthase (the genes encoding for NADH oxidoreductase subunits were absent), two rRNAs and 23 tRNA genes which recognized codons for all amino acids. A single intron interrupted the cytochrome oxidase subunit 1 gene. A number of reasons contributed towards its strikingly small size, namely: (1) the remarkable size reduction (by >40%) of the rns and rnl genes; (2) that most tRNA genes and five of the seven protein-coding genes were the shortest among known yeast homologs; and (3) that the noncoding regions were restricted to 5.1% of the genome. In addition, the genome showed multiple changes in the orientation of transcription and the gene order differed drastically from other yeasts. When all protein coding gene sequences were considered as one unit and were compared with the corresponding molecules from all other complete mtDNAs of yeasts, the phylogenetic trees constructed robustly supported its placement basal to the yeast species of the ,Saccharomyces complex', demonstrating the advantage of this approach over single-gene or multigene approaches of unlinked genes. [source] High abundance of larval rockfish over Cobb Seamount, an isolated seamount in the Northeast PacificFISHERIES OCEANOGRAPHY, Issue 3 2001John F. Dower The larval fish community in the region of Cobb Seamount (500 km west of Oregon) is dominated by myctophid species commonly encountered in the subarctic North Pacific. However, during a survey in June 1992, the ichthyoplankton community within 30 km of the seamount summit was almost completely dominated by larvae of various rockfish (Sebastes) species. Given their very small size (and hence very young age) and the fact that they occurred only rarely in samples collected > 30 km from the seamount summit, we conclude that these Sebastes larvae were produced locally over Cobb Seamount. Previous studies have shown that the Cobb fish fauna is dominated by various Sebastes spp. and that, unlike other fish present on the seamount, the rockfish populations may be self-recruiting. We suggest that a persistent clockwise (i.e. downwelling) eddy, consistent with a stratified Taylor cone, plays a critical role in retaining larval rockfish over Cobb Seamount and may contribute to the process of self-recruitment. The key to the success of rockfish on Cobb and other shallow Northeast Pacific seamounts seems to be linked to their viviparous life history. [source] The effects of low summer flow on wild salmon (Salmo salar), trout (Salmo trutta) and grayling (Thymallus thymallus) in a small streamFRESHWATER BIOLOGY, Issue 12 2009W. D. RILEY Summary 1.,The effects of an experimentally imposed low summer flow on habitat use, displacement and survival of wild populations of juvenile salmon (Salmo salar), trout (Salmo trutta) and grayling (Thymallus thymallus) were investigated in a chalk stream. The habitat use and mobility of the fish in response to reduced flow was determined using passive integrated transponder-tag detector systems. 2.,Habitat use was compared to that available under different flow regimes. These consisted of an initial control phase of normal summer flow, an abrupt step change to 21 days of low flow, followed by a second control phase when normal summer flow was reinstated. First year (0+) salmon showed little change in their preferred substratum during low flow, whilst 1+ salmon increased their use of gravel and reduced that of mud during the day. Both 0+ and 1+ salmon were found in relatively deep water by day under low flow, whilst 1+ salmon preferred relatively shallow water at night. First year trout increased their use of gravel and reduced their use of mud and submerged tree roots under low flow, using relatively deep and fast flowing water by day. Older trout increased their use of gravel and occupied relatively deep, slow flowing water by day and relatively fast and shallow water at night. Grayling showed little change in their preferred substratum, but occupied relatively shallow water following the introduction of low flow. 3.,The range of movement of juvenile salmon increased at night under low flow, and was greater by day under normal flow. There was also an initial increase in the range of movement of 0+ trout following the introduction of low flow. Older trout initially moved less under low flow. With reduced flow, the range of movement by grayling increased significantly during the day. 4.,There was no net downstream displacement of any species with reduced flow, but the mortality rate in 0+ salmon, trout and grayling increased. This may be related to their small size and increased vulnerability to predation under low flow, and due to the reduction in depth and loss of the stream margins that are normally the preferred habitat of 0+ trout and grayling. 5.,The findings of this field study have implications for the management of braided, and highly regulated, chalk stream systems. In particular, they underline the importance of the stream margins as juvenile salmonid habitat, and suggest that a flow management strategy is required to mitigate for drought conditions. Such a strategy might include pre-emptive controls on abstraction and the maintenance of river flow via a prioritised route, predetermined using fish or habitat surveys, to minimise the effects of drought conditions on the more vulnerable or valued fish groups. [source] Why are species' body size distributions usually skewed to the right?FUNCTIONAL ECOLOGY, Issue 4 2002Jan Koz, owski Summary 1.,Species' body size distributions are right-skewed, symmetric or left-skewed, but right-skewness strongly prevails. 2.,Skewness changes with taxonomic level, with a tendency to high right-skewness in classes and diverse skewness in orders within a class. Where the number of lower taxa allows for analysis, skewness coefficients have normal distributions, with the majority of taxa being right-skewed. 3.,Skewness changes with geographical scale. For a broad range, distributions in a class are usually right-skewed. For a narrower scale, distributions remain right-skewed or become symmetric or even close to uniform. 4.,The prevailing right-skewness of species' body size distributions is explained with macroevolutionary models, the fractal character of the environment, or body size optimization. 5.,Macroevolutionary models assume either size-biased speciation and extinction, or the existence of a constraint on small size. Macroevolutionary mechanisms seem insufficient to explain the pattern of species' body size distributions, but they may operate together with other mechanisms. 6.,Optimization models assume that directional and then stabilizing selection works after speciation events. There are two kinds of optimization approaches to study species' body size distributions. Under the first approach, it is assumed that a single energetic optimum exists for an entire taxon, and that species are distributed around this optimum. Under the second approach, each species has a separate optimum, and the species' body size distribution reflects the distribution of optimal values. 7.,Because not only energetic properties but also mortality are important in determining optimal sizes, only the second approach, that is, seeking the distribution of optimal values, seems appropriate in the context of life-history evolution. This approach predicts diverse shapes of body size distributions, with right-skewness prevailing. [source] Lipid-Like Nanoparticles for Small Interfering RNA Delivery to Endothelial CellsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Seung-Woo Cho Abstract Here, nanoparticles composed of lipid-like materials (lipidoids) to facilitate non-viral delivery of small interfering RNA (siRNA) to endothelial cells (ECs) are developed. Nanoparticles composed of siRNA and lipidoids with small size (,200,nm) and positive charge (,34,mV) are formed by self-assembly of lipidoids and siRNA. Ten lipidoids are synthesized and screened for their ability to facilitate the delivery of siRNA into ECs. Particles composed of leading lipidoids show significantly better delivery to ECs than a leading commercially available transfection reagent, Lipofectamine 2000. As a model of potential therapeutic application, nanoparticles composed of the top performing lipidoid, NA114, are studied for their ability to deliver siRNA targeting anti-angiogenic factor (SHP-1) to human ECs. Silencing of SHP-1 expression significantly enhances EC proliferation and decreases EC apoptosis under a simulated ischemic condition. [source] Analysis of hopanes and steranes in single oil-bearing fluid inclusions using time-of-flight secondary ion mass spectrometry (ToF-SIMS)GEOBIOLOGY, Issue 1 2010S. SILJESTRÖM Steranes and hopanes are organic biomarkers used as indicators for the first appearance of eukaryotes and cyanobacteria on Earth. Oil-bearing fluid inclusions may provide a contamination-free source of Precambrian biomarkers, as the oil has been secluded from the environment since the formation of the inclusion. However, analysis of biomarkers in single oil-bearing fluid inclusions, which is often necessary due to the presence of different generations of inclusions, has not been possible due to the small size of most inclusions. Here, we have used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to monitor in real time the opening of individual inclusions trapped in hydrothermal veins of fluorite and calcite and containing oil from Ordovician source rocks. Opening of the inclusions was performed by using a focused C60+ ion beam and the in situ content was precisely analysed for C27,C29 steranes and C29,C32 hopanes using Bi3+ as primary ions. The capacity to unambiguously detect these biomarkers in the picoliter amount of crude oil from a single, normal-sized (15,30 ,m in diameter) inclusion makes the approach promising in the search of organic biomarkers for life's early evolution on Earth. [source] Caribbean Transnational Return Migrants as Agents of ChangeGEOGRAPHY COMPASS (ELECTRONIC), Issue 1 2007Dennis Conway This article challenges several of the firmly held convictions drawn from extant research on return migration to the Caribbean. For many contemporary small island societies undergoing rapid change and transformation, modernization and integration into the wider global economy, today's younger and more youthful return migrants are no longer an ineffective demographic cohort. Despite their numerically small size, many are demonstrating they can be influential "agents of change." No longer merely returning retirees, they are more diverse, in terms of age, life-course transitions, class and gendered social positions, family networks, and migration histories. Multiple identities are the rule, rather than the exception, as returnees of different ages choose to live, work (and play) in island society, to give something back to the island home of their parents or of their youth. Many embrace transnational strategies to live in and between two worlds, or more if their family network's reach is multilocal. [source] How good is the fossil record of arthropods?GEOLOGICAL JOURNAL, Issue 3-4 2001An assessment using the stratigraphic congruence of cladograms Abstract A total of 179 published cladograms of arthropods was tested for their congruence with the palaeontological record. Congruence for data sets including 510 tetrapod and 157 fish trees was also calculated for comparison. Results provide support for the hypothesis that the fossil record of arthropods is less complete (at levels of stratigraphic and taxonomic resolution pertinent to most macroevolutionary studies) than the records of several other taxa. Differences in tree size, shape, balance and the distribution of first stratigraphic appearances (potential sources of bias) were controlled for by various randomization procedures. Most measures of congruence for arthropods were statistically poorer than those for other groups, even when the sample was divided into broad temporal bins. Many of the most robust and widely reproduced sister groupings of arthropods are attended by ghost ranges of many tens or hundreds of millions of years. Fossils of a number of presently very diverse and abundant arthropod groups are conspicuously absent from the record, despite many spectacular examples of the detailed preservation of others. There is probably no single reason for the apparently poor record of arthropods. Low preservation potential, small size of individuals, small numbers of individuals, and restricted palaeobiogeography almost certainly play a role in particular cases. Copyright © 2001 John Wiley & Sons, Ltd. [source] Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS-Mediated Cell InjuryADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Guy Applerot Abstract An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron-spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer-scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles. [source] Alteration of the food web along the Antarctic Peninsula in response to a regional warming trendGLOBAL CHANGE BIOLOGY, Issue 12 2004Mark A. Moline Abstract In the nearshore coastal waters along the Antarctic Peninsula, a recurrent shift in phytoplankton community structure, from diatoms to cryptophytes, has been documented. The shift was observed in consecutive years (1991,1996) during the austral summer and was correlated in time and space with glacial melt-water runoff and reduced surface water salinities. Elevated temperatures along the Peninsula will increase the extent of coastal melt-water zones and the seasonal prevalence of cryptophytes. This is significant because a change from diatoms to cryptophytes represents a marked shift in the size distribution of the phytoplankton community, which will, in turn, impact the zooplankton assemblage. Cryptophytes, because of their small size, are not grazed efficiently by Antarctic krill, a keystone species in the food web. An increase in the abundance and relative proportion of cryptophytes in coastal waters along the Peninsula will likely cause a shift in the spatial distribution of krill and may allow also for the rapid asexual proliferation of carbon poor gelatinous zooplankton, salps in particular. This scenario may account for the reported increase in the frequency of occurrence and abundance of large swarms of salps within the region. Salps are not a preferred food source for organisms that occupy higher trophic levels in the food web, specifically penguins and seals, and thus negative feedbacks to the ecology of these consumers can be anticipated as a consequence of shifts in phytoplankton community composition. [source] Pure-Phase Transport and Dissolution of TCE in Sedimentary Rock SaproliteGROUND WATER, Issue 3 2006M. Lenczewski The objective of this study was to experimentally determine the influence of pore structure on the transport and dissolution of trichloroethylene (TCE) in clay-rich saprolite. In order to simulate a "spill," pure-phase TCE containing a water-insoluble fluorescent dye was injected into two heterogeneous 24-cm-diameter by 37-cm-long undisturbed columns of water-saturated saprolite. TCE entry occurred at capillary pressures of 2.7 and 4.0 kPa. Ten or 28 d after injection, the column was sliced horizontally into three sections and visually examined. The distribution of fluorescent dye indicated that pure-phase TCE migrated mainly through fractures in the shale saprolite and through fine root holes or other macropores in the limestone saprolite residuum. Analysis of saprolite subsamples indicated that TCE was present throughout much of the saprolite column but usually at concentrations less than the solubility of TCE. This spreading was caused by diffusion, which also contributed to the rapid dissolution of TCE in the fractures and macropores. Modeling was carried out using previously published dissolution and diffusion equations. The calculations confirm that rapid disappearance of immiscible TCE can occur in this type of material because of the small size of fracture or macropore openings and the high porosity of the fine-grained material. This study indicates that industrial solvents can readily enter fractures and macropores in otherwise very fine-grained subsoils and then rapidly dissolve and diffuse into the fine-pore structure, fromc which they may be very difficult to remove. [source] Evaluation of an Inexpensive Small-Diameter Temperature Logger for Documenting Ground Water,River InteractionsGROUND WATER MONITORING & REMEDIATION, Issue 4 2005Adam N. Johnson Increasing numbers of studies are recording detailed temperature data for characterization of ground water,stream exchange. We examined laboratory and field operation of a small-diameter, stand-alone and inexpensive temperature logger capable of investigating stream,ground water exchange was examined. The Thermochron iButton is a 17.35-mm-diameter by 6-mm-thick instrument that costs <$10 when ordered in quantity. Testing of the loggers in a controlled temperature bath revealed a precision of ±0.4°C and an accuracy of ±0.5°C for a group of 201. More than 500 loggers have been installed in channels and in subchannel and floodplain ground water environments in two gravel-bedded rivers in the western United States. Loggers were placed as single devices and in vertical arrays in monitoring wells with diameters of 10.16, 5.08, 2.54, and 1.9 cm. We determined that the loggers have four principal advantages over more commonly used wired and currently available stand-alone logging devices: (1) the wireless nature does not require the instrument location to be associated with a control-recording system; (2) the small size allows for installation in small hand-driven or direct-push monitoring wells and thus intimate contact of the instruments with the hydrologic environment; (3) multiple loggers are easily suspended in a single fully perforated monitoring well, allowing for the collection of high-resolution temperature profile data; and (4) the low cost of the loggers allows for the deployment of large numbers, thus improving spatial resolution in shallow ground water floodplain scale studies. [source] Nutrition and pharyngeal cancer: Results from a case-control study in SpainHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 9 2002Ana Escribano Uzcudun MD Abstract Background Oropharyngeal and hypopharyngeal cancer is increasing all over the world, frequently affecting more and more women and younger individuals and not only the typical 50- to 60-year-old heavy smoker and drinking man. In addition, 5-year overall survival rate remains poor (30% to 40% in most series), despite advances in treatment. Therefore, it is crucial to understand as accurately as possible the risk factors for these malignancies to improve primary prevention. Methods We report the results from a case-control study of pharyngeal cancer risk factors conducted in Spain involving 232 consecutive patients who were gender- and age-matched with 232 controls. Data were collected by interviewer-administered personal interview. Results Our results show that low intake of fruit, fruit juice, uncooked vegetables, dietary fiber,containing foods (legume and cereals), fish, milk, and dairy products is an independent risk factor for pharyngeal cancer and that high consumption of meat and fried foods also increases the risk once data are adjusted for tobacco smoking and alcohol drinking. Conclusions Although findings for fruit, juice, and uncooked vegetables are in accordance with those from other authors and can be explained on a biologic basis, the relationship between pharyngeal cancer and dietary excess of saturated fatty acids needs experimental investigation. Findings for milk, dairy products, and fish also warrant more detailed epidemiologic research because of conflicting data reported in the literature and because of the reportedly ambiguous role of retinol in human cancers. No conclusive explanations for the protective effect of dietary fiber,containing foods can be put forward today. Our results are uniquely attributable to oropharyngeal and hypopharyngeal cancers because of the small size of our nasopharyngeal cancer subsample. © 2002 Wiley Periodicals, Inc. Head Neck 24: 830,840, 2002 [source] Conjugated Oligoelectrolyte Harnessed Polyhedral Oligomeric Silsesquioxane as Light-Up Hybrid Nanodot for Two-Photon Fluorescence Imaging of Cellular NucleusADVANCED MATERIALS, Issue 37 2010Kan-Yi Pu A water-soluble organic/inorganic hybrid nanodot based on polyhedral oligomeric silsesquioxane (POSS) and conjugated oligoelectrolyte is designed and synthesized for two-photon fluorescence imaging of cellular nucleus, which takes advantage of its small size (,3.3 nm) that imparts nucleus permeability and substantial DNA-enhanced two-photon excited fluorescence that allows illuminating the nucleus with a high contrast. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||