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Selected AbstractsParticle path length distributions in meandering gravel-bed streams: results from physical modelsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2003Richard S. Pyrce Abstract In gravel-bed rivers with well-de,ned pool,bar morphology, the path length of transported bed particles must be, at least during ,channel-forming' ,ows, equal to the length scale of the morphology. This is the basis for some methods for estimating bed material transport rates. However, previous data, especially from ,eld tests, are often strongly positively skewed with mean much shorter than the pool,bar spacing. One possible explanation is that positively skewed distributions occur only in channels lacking distinct pool,bar topography or only at lower discharges in pool,bar channels. A series of ,ume experiments using ,uorescent tracers was used to measure path length distributions in low-sinuosity meandering channels to assess the relation with channel morphology and ,ow conditions. At channel-forming ,ows, 55 to 75 per cent of the tracer grains were deposited on the ,rst point bar downstream of the point of tracer input, with 15 per cent passing beyond the ,rst bar. Path length distributions are symmetrical with mean equal to the pool,bar spacing and can be described with a Cauchy distribution. In some cases there was a secondary mode close to the point of tracer introduction; this bimodal distribution ,ts a combined gamma,Cauchy distribution. Only when discharge was reduced below the channel-forming ,ow were frequency distributions unimodal and positively skewed with no relation to the pool,bar spacing. Thus, path length distributions become more symmetrical, and mean path length increases to coincide with pool,bar spacing, as ,ow approaches channel-forming conditions. This is a substantial modi,cation of existing models of particle transfer in gravel-bed rivers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Among- and within-population variability in tolerance to cadmium stress in natural populations of Daphnia magna: Implications for ecological risk assessmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2002Carlos Barata Abstract Previous attempts to test the hypothesis that laboratory selection of isogenetic populations can produce test organisms with a significantly increased mean tolerance to toxic substances have failed. One possible explanation for such failure is that the tolerance of laboratory populations is largely constrained by their origins (were the source populations composed of tolerant genotypes?). To address this question, among- and within-population variability in stress tolerance was assessed by calculating the variance in individual fitness and longevity across a cadmium gradient (0,10 ,g/L). The study employed Daphnia magna clones from four geographically separate European populations. Results revealed significant differences in tolerance to lethal levels of toxic stress among populations. The distribution of tolerances within two of the studied populations showed high amounts of genetic variation in tolerance. Genetic relationships between tolerance traits and life history performance under nonstressful environments differed among the studied populations. One population showed significant but low costs associated with tolerance, whereas no costs were associated with tolerance in the other population. These results suggest that laboratory selection will favor individuals with high fitness or reproductive performance under optimal laboratory conditions resulting in laboratory populations with similar or lower tolerance to toxic stress than their original field populations. Given that populations can exhibit high levels of genetic variability in tolerance to toxic stress, minimizing genetic diversity in toxicity tests will increase the uncertainty attendant in extrapolating from the lab to the field. [source] Root production and demography in a california annual grassland under elevated atmospheric carbon dioxideGLOBAL CHANGE BIOLOGY, Issue 9 2002Paul A. T. Higgins Abstract This study examined root production and turnover in a California grassland during the third year of a long-term experiment with ambient (LO) and twice-ambient atmospheric CO2 (HI), using harvests, ingrowth cores, and minirhizotrons. Based on one-time harvest data, root biomass was 32% greater in the HI treatment, comparable to the stimulation of aboveground production during the study year. However, the 30,70% increase in photosynthesis under elevated CO2 for the dominant species in our system is considerably larger than the combined increase in above and belowground biomass. One possible explanation is, increased root turnover, which could be a sink for the additional fixed carbon. Cumulative root production in ingrowth cores from both treatments harvested at four dates was 2,3 times that in the single harvested cores, suggesting substantial root turnover within the growing season. Minirhizotron data confirmed this result, demonstrating that production and mortality occurred simultaneously through much of the season. As a result, cumulative root production was 54%, 47% and 44% greater than peak standing root length for the no chamber (X), LO, and HI plots, respectively. Elevated CO2, however, had little effect on rates of turnover (i.e. rates of turnover were equal in the LO and HI plots throughout most of the year) and cumulative root production was unaffected by treatment. Elevated CO2 increased monthly production of new root length (59%) only at the end of the season (April,June) when root growth had largely ceased in the LO plots but continued in the HI plots. This end-of-season increase in production coincided with an 18% greater soil moisture content in the HI plots previously described. Total standing root length was not affected by CO2 treatment. Root mortality was unaffected by elevated CO2 in all months except April, in which plants grown in the HI plots had higher mortality rates. Together, these results demonstrate that root turnover is considerable in the grassland community and easily missed by destructive soil coring. However, increased fine root turnover under elevated CO2 is apparently not a major sink for extra photosynthate in this system. [source] Odor processing in multiple chemical sensitivityHUMAN BRAIN MAPPING, Issue 3 2007Lena Hillert Abstract Multiple chemical sensitivity (MCS) is characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the mechanisms behind the reported hypersensitivity are unknown. Using the advantage of the well-defined trigger (odor), we investigated whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits. Positron emission tomography (PET) activation studies with several different odorants were carried out in 12 MCS females and 12 female controls. Activation was defined as a significant increase in regional cerebral blood flow (rCBF) during smelling of the respective odorant compared to smelling of odorless air. The study also included online measurements of respiratory frequency and amplitude and heart rate variations by recording of R wave intervals (RR) on the surface electrocardiogram. The MCS subjects activated odor-processing brain regions less than controls, despite the reported, and physiologically indicated (decreased RR interval) distress. In parallel, they showed an odorant-related increase in activation of the anterior cingulate cortex and cuneus-precuneus. Notably, the baseline rCBF was normal. Thus, the abnormal patterns were observed only in response to odor signals. Subjects with MCS process odors differently from controls, however, without signs of neuronal sensitization. One possible explanation for the observed pattern of activation in MCS is a top-down regulation of odor-response via cingulate cortex. Hum. Brain Mapp, 2007. © 2006 Wiley-Liss, Inc. [source] The Spatial Segregation of Zooplankton Communities with Reference to Land Use and Macrophytes in Shallow Lake Wielkowiejskie (Poland)INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2009Natalia Kuczy, ska-Kippen Abstract The spatial distribution of zooplankton in relation to two types of land-use (forested and pastoral-arable) of a lake's surroundings and to various habitats (helophytes, elodeids, nymphaeids and open water) was examined along 16 parallel transects on a macrophyte-dominated lake (area , 13.3 ha; mean depth , 1.4 m). The type of habitat was the main determinant of zooplankton community structure. Dissected-leaved elodeids harboured the richest and most abundant community with typically littoral (e.g., Colurella uncinata) and pelagic species (e.g., Keratella cochlearis). Two species (Polyarthra major and P. vulgaris) selectively chose the open water and one (Lecane quadridentata) the Typha stand. No spatial differentiation in zooplankton abundance was recorded between the two types of the catchment area. One possible explanation may be the shallowness and small area of this lake which may support full mixing and no difference in physical-chemical gradients. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Protein profile study in European eel (Anguilla anguilla) seminal plasma and its correlation with sperm qualityJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2010D. S. Peñaranda Summary Along with sperm quality parameters, the protein profile of European eel seminal plasma was analyzed during induced spermiation (n = 56 samples). Motility, Percentage of live cells, spermatozoa head morphometry and concentration showed low values during the initial weeks of spermiation and maintained high levels throughout the rest of the experiment. The protein profile gradient by SDS-PAGE (4,15%) registered four important electrophoretic bands around 80, 40, 26 and 12 KDa. Three of them showed significant differences in concentration during treatment (80, 40 and 12 KDa), and all of them showed the highest value on the 8th week. Both 80 and 12 KDa bands increased until the 8th week, followed by a progressive decline. One possible explanation for these profiles is that, in the first weeks of treatment, proteins originated from blood plasma are accumulated in the seminal plasma, and from the 8th week some of these proteins are incorporated into the spermatic membranes. The 40 KDa protein band also increased during the first 8 weeks, but maintained high concentrations in the seminal plasma for the rest of the experiment. One result confirms the theory that the presence of proteins in the seminal plasma having a molecular weight lower than 50 KDa increased spermatozoa motility, since the 40 KDa band displayed significantly higher values coinciding with the high percentages of spermatozoa motility. Seminal plasma proteins seem to have an important role in spermatogenesis and spermatozoa movement, but further studies are necessary to discover the identity of these proteins and their precise functions. [source] Evidence-Based assessment with menJOURNAL OF CLINICAL PSYCHOLOGY, Issue 6 2005Sam V. Cochran Men are almost universally underrepresented in psychological clinics and practices in the United States. One possible explanation for this underrepresentation is that men frequently conceal or obscure their emotional difficulties as a consequence of masculine gender role socialization. Men who subscribe to traditional, Western masculine values may be inclined to hide, minimize, or otherwise have difficulty expressing their psychological suffering, rendering this suffering difficult for clinicians to observe, diagnose, and treat. This manuscript describes an approach to the assessment process with men that integrates clinical reports on assessment and psychotherapy with men, values pertaining to our culture's construction of traditional masculinity, and empirical findings on psychological disorders more commonly observed in men. © 2005 Wiley Periodicals, Inc. J Clin Psychol 61: 649,660, 2005. [source] Do psychological prices contribute to price rigidity?AGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 1 2006Evidence from German scanner data on food brands A substantial degree of price rigidity has been reported for branded foods in various studies with scanner data. One possible explanation for price rigidity is the existence of psychological pricing points. The authors analyze to what extent psychological pricing plays a role in grocery retailing and whether it contributes to the price rigidity of branded foods in Germany. Psychological pricing,defined here as just-below-the-round-figure-pricing,is empirically analyzed with scanner data of weekly prices for 20 food brands in 38 retail outlets from September 1996 to June 1999. Psychological pricing turned out to be extremely important in German food retailing. Branded food prices are remarkably sticky and psychological pricing points contribute strongly to price rigidity. Other factors like the sales phenomenon and firm-specific effects are additionally important. [EconLit Classifications: Q110, Q130]. © 2006 Wiley Periodicals, Inc. Agribusiness 22: 51,67, 2006. [source] Medial collateral ligament autografts have increased creep response for at least two years and early immobilization makes this worseJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2002G. M. Thornton Recent evidence has shown that 10,40% of knee joints reconstructed with soft-tissue autografts have a recurrence of abnormal joint laxity over time. One possible explanation is the "stretching out" (or unrecovered creep) of the graft tissue. To test in vitro creep and creep recovery of fresh anatomic ligament autografts in an extra-articular environment, 16 rabbits underwent an orthotopic medial collateral ligament (MCL) autograft procedure to one hindlimb. Three subgroups of animals had either unrestricted cage activity for 1 year (n = 5) or 2 years (n = 5) or pin-immobilization for the first 6 weeks followed by cage activity for the remainder of 1 year (n = 6). Following laxity measurements, to test their creep response, isolated MCL grafts were cyclically and then statically creep tested in vitro at 4.1 MPa, allowed to recover at zero load for 20 min, and finally elongated to failure. Due to differences in cross-sectional area between the grafts and normal MCLs, two normal control groups were tested: stress-matched tested at 4.1 MPa (16.2 N; n = 7) and force-matched tested at 29.1 N (7.1 MPa; n = 6). Ligament grafts had normal laxity but significantly increased creep and decreased creep recovery compared to normal MCLs after 1 and 2 years of healing (p < 0.0004). Graft failure stress was also significantly less than normal (p < 0.0001). Immobilized grafts had significantly greater creep compared to non-immobilized grafts at 1 year of healing (p < 0.05). These results support previous observations concerning material inferiority of fresh anatomic rabbit MCL autografts, but add the concept that such grafts also have increased potential to creep with either slower or incomplete recovery when subjected to low stresses in vitro. Joint and ligament laxities in situ were normal in this model, however, suggesting either that in vivo MCL graft stresses are lower than those used here in vitro or that these tissues have other mechanisms by which they can recover their functional length in vivo. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Effects of non-steady-state iron limitation on nitrogen assimilatory enzymes in the marine diatom thalassiosira weissflogii (BACILLARIOPHYCEAE)JOURNAL OF PHYCOLOGY, Issue 1 2000Allen J. Milligan Since the recognition of iron-limited high nitrate (or nutrient) low chlorophyll (HNLC) regions of the ocean, low iron availability has been hypothesized to limit the assimilation of nitrate by diatoms. To determine the influence of non-steady-state iron availability on nitrogen assimilatory enzymes, cultures of Thalassiosira weissflogii (Grunow) Fryxell et Hasle were grown under iron-limited and iron-replete conditions using artificial seawater medium. Iron-limited cultures suffered from decreased efficiency of PSII as indicated by the DCMU-induced variable fluorescence signal (Fv/Fm). Under iron-replete conditions, in vitro nitrate reductase (NR) activity was rate limiting to nitrogen assimilation and in vitro nitrite reductase (NiR) activity was 50-fold higher. Under iron limitation, cultures excreted up to 100 fmol NO2,·cell,1·d,1 (about 10% of incorporated N) and NiR activities declined by 50-fold while internal NO2, pools remained relatively constant. Activities of both NR and NiR remained in excess of nitrogen incorporation rates throughout iron-limited growth. One possible explanation is that the supply of photosynthetically derived reductant to NiR may be responsible for the limitation of nitrogen assimilation at the NO2, reduction step. Urease activity showed no response to iron limitation. Carbon:nitrogen ratios were equivalent in both iron conditions, indicating that, relative to carbon, nitrogen was assimilated at similar rates whether iron was limiting growth or not. We hypothesize that, diatoms in HNLC regions are not deficient in their ability to assimilate nitrate when they are iron limited. Rather, it appears that diatoms are limited in their ability to process photons within the photosynthetic electron transport chain which results in nitrite reduction becoming the rate-limiting step in nitrogenassimilation. [source] Nicotine Decreases Blood Alcohol Concentrations in Adult Rats: A Phenomenon Potentially Related to Gastric FunctionALCOHOLISM, Issue 8 2006Scott E. Parnell Background: In spite of the fact that drinking and smoking often occur together, little is known about the pharmacokinetic interaction between alcohol and nicotine. Previous research in neonatal rats demonstrated that nicotine reduces blood alcohol concentrations (BACs) if alcohol and nicotine are administered simultaneously. However, it is unclear whether such a phenomenon can be observed in adult subjects, given the fact that there is an ontogenetic difference in alcohol metabolism. Methods: A range of nicotine doses (0, 0.25, 0.5, 1, 2, 4, and 6 mg/kg) were administered individually with an alcohol dose (4 g/kg) via intragastric (IG) intubation to adult female rats, and the resultant BACs were measured at various time points following drug administration. Furthermore, the hypothesis that nicotine's role in reducing BACs is mediated through factors related to gastric function was examined by comparing the resultant BACs after an IG intubation or intraperitoneal (IP) injection of alcohol. Results: The results from this study showed significant nicotine dose,related decreases in BACs with 0.5, 1, 2, 4, and 6 mg/kg doses of nicotine at the various time points assessed. This effect, however, occurred only when alcohol was administered via IG intubation, but not after an IP injection of alcohol. Conclusions: These results suggest that the nicotine-induced decrease in BAC may be related to gastric function. One possible explanation was related to nicotine's action in delaying gastric emptying. The longer the alcohol was retained in the stomach, the more likely that the alcohol would be metabolized by gastric alcohol dehydrogenase before its absorption into the bloodstream by the small intestine (the major site of alcohol absorption). [source] Precambrian animal life: Taphonomy of phosphatized metazoan embryos from southwest ChinaLETHAIA, Issue 2 2005DORNBOS STEPHEN Phosphatized fossils from the Neoproterozoic Doushantuo Formation have provided valuable insight into the early evolution of metazoans, but the preservation of these spectacular fossils is not yet fully understood. This research begins to address this issue by performing a detailed specimen-based taphonomic analysis of the Doushantuo Formation phosphatized metazoan embryos. A total of 206 embryos in 65 thin sections from the Weng'an Phosphorite Member of the Doushantuo Formation were examined and their levels of pre-phosphatization decay estimated. The data produced from this examination reveal a strong taphonomic bias toward earlier (2-cell and 4-cell) cleavage stages, which tend to be well-preserved, and away from later (8-cell and 16-cell) cleavage stages, which tend to exhibit evidence for slight to intense levels of organic decay. In addition, the natural abundances of these embryos tend to decrease with advancement in cleavage stage, and no evidence of more advanced (beyond 16-cell) cleavage stages or eventual adult forms were found in this study. One possible explanation for this taphonomic bias toward early cleavage stages is that later cleavage stages and adult forms were more physically delicate, allowing them to be more easily damaged during burial and reworking, allowing for more rapid decay. The spectacular preservation of these embryos was probably aided by their likely internal enrichment in phosphate-rich yolk, which would have caused their internal dissolved phosphate levels to reach critical levels with only miniscule organic decay, thereby hastening phosphatization. If internal sources of phosphate did indeed play a role in the phosphatization of these embryos, it may explain their prolific abundance in these rocks compared to other phosphatized fossils as well as indicating that metazoans lacking such internal phosphate sources were likely much more difficult to preserve. The phosphatic fossils of the Doushantuo Formation, therefore, provide an indispensable, yet restricted, window into Neoproterozoic life and metazoan origins. [source] Anomalous SZ contribution to three-year WMAP dataMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007R. M. Bielby ABSTRACT We first show that the new Wilkinson Microwave Anisotropy Probe (WMAP) 3-yr data confirm the detection by Myers et al. of an extended SZ signal centred on 606 Abell (ACO) clusters with richness class, R, 2. Our results also show SZ decrements around APM and 2MASS groups at increased significance than previously detected. We then follow the approach of Lieu, Mittaz & Zhang and compare the stacked WMAP results for the decrement in 31 clusters with ROSAT X-ray profiles where Lieu et al. found on average less SZ decrement in the WMAP 1-yr data than predicted. We confirm that in the 3-yr data these same clusters again show less SZ decrement than the X-ray data predict. We then analysed the WMAP results for the 38 X-ray clusters with OVRO/BIMA measured SZ decrements as presented by Bonamente et al.. We again find that the average decrement is measured to be significantly less (5.5,) than predicted by the Chandra X-ray data. Thus while we confirm the original detection of an extended SZ effect by Myers et al., these X-ray comparisons may now suggest that the central SZ amplitudes detected by WMAP may actually be lower than expected. One possible explanation is that there is contamination of the WMAP SZ signal by radio sources in the clusters but we argue that this appears implausible. We then consider the possibility that the SZ decrement has been lensed away by foreground galaxy groups. Such a model predicts that the SZ decrement should depend on cluster redshift. A reduction in the SZ decrement with redshift is suggested from the ACO cluster sample and also from comparing the samples of Lieu et al. and Bonamente et al.. However, the mass power spectrum would require a far higher amplitude than currently expected if lensing was to explain the SZ deficit in high-redshift clusters. [source] Elements of a theory of Ukrainian ethno-national identitiesNATIONS AND NATIONALISM, Issue 1 2002Andrew Wilson Despite winning independence in 1991, Ukraine remains an amorphous society with a weak sense of national identity. One possible explanation is ,late' nation-creation, but in this article emphasis is laid on a continuing plurality of identity projects and the legacy of the ,failed' identity-building projects of the past. Ukraine's most important distinguishing feature , the existence of a substantial middle ground between Ukrainian and Russian identities , has considerable capacity to resist the logic of consolidating statehood. [source] Effects of altered water regimes on forest root systemsNEW PHYTOLOGIST, Issue 1 2000J. D. JOSLIN How ecosystems adapt to climate changes depends in part on how individual trees allocate resources to their components. A review of research using tree seedlings provides some support for the hypothesis that some tree species respond to exposure to drought with increases in root,shoot ratios but little change in total root biomass. Limited research on mature trees over moderately long time periods (2,10 yr), has given mixed results with some studies also providing evidence for increases in root: shoot ratios. The Throughfall Displacement Experiment (TDE) was designed to simulate both an increase and a decrease of 33% in water inputs to a mature deciduous forest over a number of years. Belowground research on TDE was designed to examine four hypothesized responses to long-term decreases in water availability; (1) increases in fine-root biomass, (2) increases in fine root,foliage ratio, (3) altered rates of fine-root turnover (FRT), and (4) depth of rooting. Minirhizotron root elongation data from 1994 to 1998 were examined to evaluate the first three hypotheses. Differences across treatments in net fine-root production (using minirhizotron root elongation observations as indices of biomass production) were small and not significant. Periods of lower root production in the dry treatment were compensated for by higher growth during favorable periods. Although not statistically significant, both the highest production (20 to 60% higher) and mortality (18 to 34% higher) rates were found in the wet treatment, resulting in the highest index of FRT. After 5 yr, a clear picture of stand fine-root-system response to drought exposure has yet to emerge in this forest ecosystem. Our results provide little support for either an increase in net fine-root production or a shift towards an increasing root,shoot ratio with long-term drought exposure. One possible explanation for higher FRT rates in the wet treatment could be a positive relationship between FRT and nitrogen and other nutrient availability, as treatments have apparently resulted in increased immobilization of nutrients in the forest floor litter under drier conditions. Such hypotheses point to the continued need to study the interactions of water stress, nutrient availability and carbon-fixation efficiency in future long-term studies. [source] The prevalence of suppression in amblyopic individualsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2008Brendan Barrett Purpose:, A popular view of visual functioning in individuals with amblyopia is that the weaker eye is suppressed in key regions of the binocular visual field. Indeed, some have argued that chronic interocular suppression may represent the cause of amblyopia. Here we evaluate the prevalence of amblyopic-eye suppression in a simple light detection task when the eyes are open, minimally dissociated and in their habitual motor position. Methods:, A custom program on the Humphrey Field Analyzer (Carl Zeiss Meditec Inc., Dublin, CA, USA) was used to measure detection thresholds for a blue light on a yellow background along the horizontal meridian at two-degree intervals to an eccentricity of 25 degrees on either side of the fixation mark. The fellow eye was prevented from seeing the target using three different methods: (1) full-occlusion (i.e. no light entered the fellow eye), (2) a translucent occluder (3) a yellow filter in front of the fellow eye. In (3), the yellow filter only prevented the fellow eye from seeing the blue stimulus; the fixation mark and the background remained visible (minimal-dissociation condition). Fourteen amblyopes participated in the study, of whom 11 had strabismus. Results:, Three basic patterns of results were observed. (1) Only three of the fourteen participants (,21%) showed evidence of suppression, where amblyopic-eye sensitivity was lower with the fellow eye open. In these cases, the retinal locations that showed greatest suppression corresponded to the direction and angle of the strabismus. (2) Three participants (,21%) showed the opposite effect to the result in (1); i.e. amblyopic-eye sensitivity was greatest when the fellow was open with minimal dissociation between the eyes. One possible explanation is that the dominance of the fellow eye caused this reduction. (3) Seven participants (50%) exhibited patterns of amblyopic sensitivity that did not depend upon the occlusion status of the fellow eye. The results for one participant did not fit into any of the above patterns. Conclusions:, Suppression appears not to be a universal feature of central amblyopic vision. Our results for this simple detection task suggest that suppression may exist in as few as 20% of amblyopes. These results present a challenge to the view that suppression represents a root cause of amblyopia but they are consistent with the view that the amblyopic eye makes a useful contribution under habitual viewing conditions. [source] Taller women do better in a stressed environment: Height and reproductive success in rural Guatemalan womenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2008Thomas V. Pollet Previous research on the relationship between height and reproductive success in women has produced mixed results. One possible explanation for these is mediation by ecological factors, such as environmental stress. Here we investigate female height and reproductive success under conditions of environmental stress (poverty) using a large scale dataset from Guatemala (n = 2,571). Controlling for educational attainment, age and ethnicity, we examined relationships between height and childlessness, occurrence of a stillbirth, fertility and child survival. There was no significant relationship between height and never haven given birth. Extremely short women had a significantly raised likelihood of experiencing stillbirth. There were curvilinear relationships between height and age at first birth, fertility, and survival rates for children. Overall, though, the penalties for short stature, particularly in terms of child survival, were far greater than those associated with extreme tallness, and so female height is positively associated with overall fitness in this population. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source] Occupational injuries by hour of day and day of week: a 20-year studyAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 6 2006Eric Wigglesworth Objective: To examine by hour of day and day of week the 750,000 compensation claims that were lodged by male workers in Queensland, Australia, during the 20-year period from 1968 to 1988, including an investigation into some possible reasons for the increased number of claims on Mondays and the reduced number of claims on Fridays. Method: The study was based on the collection entitled Industrial Accident Statistics (Bulletin 79), published annually by the Australian Bureau of Statistics, Queensland office. This was the only State collection to include data on compensated injuries categorised by hour of day and day of week. There was no Australia-wide dataset of compensated occupational injuries. Results: Compensation claims were not evenly distributed through the working week. There were more injuries on Mondays (23.6% of the total) than on Tuesdays (21.8%), than on Wednesdays (20.3%), than on Thursdays (18%), than on Fridays (16.3%). There were more injuries in the mornings than in the afternoons for every day of the working week. Conclusions and Implications: This study confirms the existence of a steady reduction in workers' compensation injury claims on successive days of the working week. One possible explanation for this finding is offered as a basis for further research into the reasons for this trend. Hopefully, the results of these and later studies may suggest remedial measures that will help reduce the number of occupational injuries. [source] Estimation and Inference for a Spline-Enhanced Population Pharmacokinetic ModelBIOMETRICS, Issue 3 2002Lang Li Summary. This article is motivated by an application where subjects were dosed three times with the same drug and the drug concentration profiles appeared to be the lowest after the third dose. One possible explanation is that the pharmacokinetic (PK) parameters vary over time. Therefore, we consider population PK models with time-varying PK parameters. These time-varying PK parameters are modeled by natural cubic spline functions in the ordinary differential equations. Mean parameters, variance components, and smoothing parameters are jointly estimated by maximizing the double penalized log likelihood. Mean functions and their derivatives are obtained by the numerical solution of ordinary differential equations. The interpretation of PK parameters in the model and its flexibility are discussed. The proposed methods are illustrated by application to the data that motivated this article. The model's performance is evaluated through simulation. [source] Increasing incidence of differentiated thyroid cancer in the United States, 1988,2005CANCER, Issue 16 2009Amy Y. Chen MD Abstract BACKGROUND: Studies have reported an increasing incidence of thyroid cancer since 1980. One possible explanation for this trend is increased detection through more widespread and aggressive use of ultrasound and image-guided biopsy. Increases resulting from increased detection are most likely to involve small primary tumors rather than larger tumors, which often present as palpable thyroid masses. The objective of the current study was to investigate the trends in increasing incidence of differentiated (papillary and follicular) thyroid cancer by size, age, race, and sex. METHODS: Cases of differentiated thyroid cancer (1988-2005) were analyzed using the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) dataset. Trends in incidence rates of papillary and follicular cancer, race, age, sex, primary tumor size (<1.0 cm, 1.0-2.9 cm, 3.0-3.9 cm, and >4 cm), and SEER stage (localized, regional, distant) were analyzed using joinpoint regression and reported as the annual percentage change (APC). RESULTS: Incidence rates increased for all sizes of tumors. Among men and women of all ages, the highest rate of increase was for primary tumors <1.0 cm among men (1997-2005: APC, 9.9) and women (1988-2005: APC, 8.6). Trends were similar between whites and blacks. Significant increases also were observed for tumors ,4 cm among men (1988-2005: APC, 3.7) and women (1988-2005: APC, 5.70) and for distant SEER stage disease among men (APC, 3.7) and women (APC, 2.3). CONCLUSIONS: The incidence rates of differentiated thyroid cancers of all sizes increased between 1988 and 2005 in both men and women. The increased incidence across all tumor sizes suggested that increased diagnostic scrutiny is not the sole explanation. Other explanations, including environmental influences and molecular pathways, should be investigated. Cancer 2009. © 2009 American Cancer Society. [source] Frequent and preferential infection of Treponema denticola, Streptococcus mitis, and Streptococcus anginosus in esophageal cancersCANCER SCIENCE, Issue 7 2004Michihiro Narikiyo Multiple cancers frequently occur in the upper digestive tract. One possible explanation is that specific bacterial infection stimulates the normal epithelium to initiate inflammation and/or promotes carcinogenesis. This study was undertaken to determine which bacterial species is predominantly associated with esophageal cancer. We examined the bacterial diversity in this type of cancer and in the saliva from healthy people by using a culture-independent molecular method. Here we report the preferential and frequent infection of the oral periodontopathic spirochete Treponema denticola (T. denticola), Streptococcus mitis (S. mitis), and Streptococus anginosus (S. anginosus) in esophageal cancer from different regions of the world, and we also describe the induction of inflammatory cytokines by infection of S. anginosus and S. mitis. Our present data suggest that these three bacteria could have significant roles in the carcinogenic process of many cases of esophageal cancer by causing inflammation and by promoting the carcinogenic process, and that eradication of these three bacteria may decrease the risk of recurrence. [source] | |||||||||||||||||||