Surrounding Environment (surrounding + environment)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Scalable Algorithm for Resolving Incorrect Occlusion in Dynamic Augmented Reality Engineering Environments

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2010
Amir H. Behzadan
As a result of introducing real-world objects into the visualization, less virtual models have to be deployed to create a realistic visual output that directly translates into less time and effort required to create, render, manipulate, manage, and update three-dimensional (3D) virtual contents (CAD model engineering) of the animated scene. At the same time, using the existing layout of land or plant as the background of visualization significantly alleviates the need to collect data about the surrounding environment prior to creating the final visualization while providing visually convincing representations of the processes being studied. In an AR animation, virtual and real objects must be simultaneously managed and accurately displayed to a user to create a visually convincing illusion of their coexistence and interaction. A critical challenge impeding this objective is the problem of incorrect occlusion that manifests itself when real objects in an AR scene partially or wholly block the view of virtual objects. In the presented research, a new AR occlusion handling system based on depth-sensing algorithms and frame buffer manipulation techniques was designed and implemented. This algorithm is capable of resolving incorrect occlusion occurring in dynamic AR environments in real time using depth-sensing equipment such as laser detection and ranging (LADAR) devices, and can be integrated into any mobile AR platform that allows a user to navigate freely and observe a dynamic AR scene from any vantage position. [source]


Electrical stimulation promotes peripheral axon regeneration by enhanced neuronal neurotrophin signaling

DEVELOPMENTAL NEUROBIOLOGY, Issue 2 2007
Arthur W. English
Abstract Electrical stimulation of cut peripheral nerves at the time of their surgical repair results in an enhancement of axon regeneration. Regeneration of axons through nerve allografts was used to evaluate whether this effect is due to an augmentation of cell autonomous neurotrophin signaling in the axons or signaling from neurotrophins produced in the surrounding environment. In the thy-1-YFP-H mouse, a single 1 h application of electrical stimulation at the time of surgical repair of the cut common fibular nerve results in a significant increase in the proportion of YFP+ dorsal root ganglion neurons, which were immunoreactive for BDNF or trkB, as well as an increase in the length of regenerating axons through allografts from wild type litter mates, both 1 and 2 weeks later. Axon growth through allografts from neurotrophin-4/5 knockout mice or grafts made acellular by repeated cycles of freezing and thawing is normally very poor, but electrical stimulation results in a growth of axons through these grafts, which is similar to that observed through grafts from wild type mice after electrical stimulation. When cut nerves in NT-4/5 knockout mice were electrically stimulated, no enhancement of axon regeneration was found. Electrical stimulation thus produces a potent enhancement of the regeneration of axons in cut peripheral nerves, which is independent of neurotrophin production by cells in their surrounding environment but is dependent on stimulation of trkB and its ligands in the regenerating axons themselves. © 2006 Wiley Periodicals, Inc. Develop Neurobiol 67: 158,172, 2007. [source]


Foraging behavior of an estuarine predator, the blue crab Callinectes sapidus in a patchy environment

ECOGRAPHY, Issue 1 2000
Mary E. Clark
To define general principles of predator-prey dynamics in an estuarine subtidal environment, we manipulated predator density (the blue crab, Callinectes sapidus) and prey (the clam, Macoma balthica) patch distribution in large field enclosures in the Rhode River subestuary of the central Chesapeake Bay. The primary objectives were to determine whether predators forage in a way that maximizes prey consumption and to assess how their foraging success is affected by density of conspecifics. We developed a novel ultrasonic telemetry system to observe behavior of individual predators with unprecedented detail. Behavior of predators was more indicative of optimal than of opportunistic foraging. Predators appeared responsive to the overall quality of prey in their habitat. Rather than remaining on a prey patch until depletion, predators appeared to vary their patch use with quality of the surrounding environment. When multiple (two) prey patches were available, residence time of predators on a prey patch was shorter than when only a single prey patch was available. Predators seemed to move among the prey patches fairly regularly, dividing their foraging time between the patches and consuming prey from each of them at a similar rate. That predators more than doubled their consumption of prey when we doubled the number of prey (by adding the second patch) is consistent with optimizing behaviors - rather than with an opportunistic increase in prey consumption brought about simply by the addition of more prey. Predators at high density, however, appeared to interfere with each other's foraging success, reflected by their lower rates of prey consumption. Blue crabs appear to forage more successfully (and their prey to experience higher mortality) in prey patches located within 15,20 meters of neighboring patch, than in isolated patches. Our results are likely to apply, at least qualitatively, to other crustacean-bivalve interactions, including those of commercial interest; their quantitative applicability will depend on the mobility of other predators and the scale of patchiness they perceive. [source]


Use of monoclonal antibodies to quantify the dynamics of ,-galactosidase and endo-1,4-,-glucanase production by Trichoderma hamatum during saprotrophic growth and sporulation in peat

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2005
Christopher R. Thornton
Summary Trichoderma species are ubiquitous soil and peat-borne saprotrophs that have received enormous scientific interest as biocontrol agents of plant diseases caused by destructive root pathogens. Mechanisms of biocontrol such as antibiosis and hyperparasitism are well documented and the biochemistry and molecular genetics of these processes defined. An aspect of biocontrol that has received little attention is the ability of Trichoderma species to compete for nutrients in their natural environments. Trichoderma species are efficient producers of polysaccharide-degrading enzymes that enable them to colonize organic matter thereby preventing the saprotrophic spread of plant pathogens. This study details the use of monoclonal antibodies (mAbs) to quantify the production of two enzymes implicated in the saprotrophic growth of Trichoderma species in peat. Using mAbs specific to the hemicellulase enzyme ,-galactosidase (AGL) and the cellulase enzyme endo-1,4-,-glucanase (EG), the relationship between the saprotrophic growth dynamics of a biocontrol strain of Trichoderma hamatum and the concomitant production of these enzymes in peat-based microcosms was studied. Enzyme activity assays and enzyme protein concentrations derived by enzyme-linked immunosorbent assay (ELISA) established the precision and sensitivity of mAb-based assays in quantifying enzyme production during active growth of the fungus. Trends in enzyme activities and protein concentrations were similar for both enzymes, during a 21-day sampling period in which active growth and sporulation of the fungus in peat was quantified using an independent mAb-based assay. There was a sharp increase in active biomass of T. hamatum 3 days after inoculation of microcosms with phialoconidia. After 3 days there was a rapid decline in active biomass which coincided with sporulation of the fungus. A similar trend was witnessed with EG activities and concentrations. This showed that EG production related directly to active growth of the fungus. The trend was not found, however, with AGL. There was a rapid increase in enzyme activities and protein concentrations on day 3, after which they remained static. The reason for the maintenance of elevated AGL probably resulted from secretion of the enzyme from conidia and chlamydospores. ELISA, immunofluoresence and immunogold electron microscopy studies of these cells showed that the enzyme is localized within the cytoplasm and is secreted extracellularly into the surrounding environment. It is postulated that release of oligosaccharides from polymeric hemicellulose by the constitutive spore-bound enzyme leads to AGL induction and could act as an environmental cue for spore germination. [source]


Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, Ukraine

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000
Brenda E. Rodgers
Abstract A population of Clethrionomys glareolus (bank vole) from a highly radioactive area within the Chornobyl, Ukraine exclusion zone was sampled in June 1997 and in June and October 1998. Internal radiation doses from radiocesium were estimated to be as high as 8 rads/d. Total dose, which takes into account the internal dose from radiostrontium and the surrounding environment, was estimated to be 15 to 20 rads/d. In contrast, individuals from a reference population lying outside of the exclusion zone registered negligible levels of contamination. We used the micronucleus test in a double-blind study to analyze blood samples from 58 individuals. We scored more than 600,000 polychromatic erythrocytes (PCEs) but could not reject the null hypothesis that the frequency of micronucleated PCEs in voles exposed to radiation was equal to the frequency in unexposed voles. Results of our study stand in sharp contrast to earlier reports of increased frequencies of micronuclei in rodents exposed to fallout of the Chornobyl accident, but with radiation doses that were orders of magnitude lower than those reported here. Radioresistance and experimental methods are possible explanations for these differences in the results. [source]


Hollow Mesoporous Zirconia Nanocapsules for Drug Delivery

ADVANCED FUNCTIONAL MATERIALS, Issue 15 2010
Shaoheng Tang
Abstract Hollow mesoporous zirconia nanocapsules (hm -ZrO2) with a hollow core/porous shell structure are demonstrated as effective vehicles for anti-cancer drug delivery. While the highly porous feature of the shell allows the drug, doxorubicin(DOX), to easily pass through between the inner void space and surrounding environment of the particles, the void space in the core endows the nanocapsules with high drug loading capacity. The larger the inner hollow diameter, the higher their DOX loading capacity. A loading of 102% related to the weight of hm -ZrO2 is achieved by the nanocapsules with an inner diameter of 385,nm. Due to their pH-dependent charge nature, hm -ZrO2 loaded DOX exhibit pH-dependent drug releasing kinetics. A lower pH offers a faster DOX release rate from hm -ZrO2. Such a property makes the loaded DOX easily release from the nanocapsules when up-taken by living cells. Although the flow cytometry reveals more uptake of hm -ZrO2 particles by normal cells, hm -ZrO2 loaded DOX release more drugs in cancer cells than in normal cells, leading to more cytotoxicity toward tumor cells and less cytotoxicity to healthy cells than free DOX. [source]


Molecular bacterial community analysis of clean rooms where spacecraft are assembled

FEMS MICROBIOLOGY ECOLOGY, Issue 3 2007
Christine Moissl
Abstract Molecular bacterial community composition was characterized from three geographically distinct spacecraft-associated clean rooms to determine whether such populations are influenced by the surrounding environment or the maintenance of the clean rooms. Samples were collected from facilities at the Jet Propulsion Laboratory (JPL), Kennedy Space Flight Center (KSC), and Johnson Space Center (JSC). Nine clone libraries representing different surfaces within the spacecraft facilities and three libraries from the surrounding air were created. Despite the highly desiccated, nutrient-bare conditions within these clean rooms, a broad diversity of bacteria was detected, covering all the main bacterial phyla. Furthermore, the bacterial communities were significantly different from each other, revealing only a small subset of microorganisms common to all locations (e.g. Sphingomonas, Staphylococcus). Samples from JSC assembly room surfaces showed the greatest diversity of bacteria, particularly within the Alpha - and Gammaproteobacteria and Actinobacteria. The bacterial community structure of KSC assembly surfaces revealed a high presence of proteobacterial groups, whereas the surface samples collected from the JPL assembly facility showed a predominance of Firmicutes. Our study presents the first extended molecular survey and comparison of NASA spacecraft assembly facilities, and provides new insights into the bacterial diversity of clean room environments . [source]


Island Biocultural Assemblages , The Case of Kinmen Island

GEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2003
Huei-Min Tsai
ABSTRACT A growing mass of research contributes to our understanding of how biological and cultural diversity are related in complex and important ways. This paper presents an assembling process of biodiversity and cultural diversity on an island, Kin-men (Quemoy), based on 1600 years of its environmental history. The study shows that the island's biocultural assemblages are a result both of external relations with the island's surrounding environment and internal relations within the island's changing human ecology. Distant political powers and economic forces are the two major external influences that have affected the flow of natural and cultural elements to and from the island, while ,screening effects' and ,isolation effects' are two factors that explain internal interactions. The island's biocultural assembling processes reveal that the openness of the island facilitates increase in the diversity of biocultural elements, while its less disturbed isolated condition fosters natural succession and co-evolution. The study suggests that biocultural assemblages and the associated processes of co-evolution and nature,society interactions are accomplished through the intermittent opportunities purposively provided by or inadvertently found in the openings and closures of boundaries, setting the scene for both boundary crossings and bounded shelter, by intent or chance. [source]


Fluorescent Polystyrene,Fe3O4 Composite Nanospheres for In Vivo Imaging and Hyperthermia

ADVANCED MATERIALS, Issue 21 2009
Donglu Shi
Quantum dots (QDs) are immobilized on the surfaces of magnetic Fe3O4 -composite nanospheres (MNSs, see figure). The QDs exhibit intense visible-light emission in fluorescence spectroscopy and successfully facilitate, for the first time, in vivo soft-tissue imaging in live mice. The Fe3O4 nanoparticles respond to an external magnetic field by increasing the temperature of the surrounding environment (i.e., hyperthermia), which can be used therapeutically. [source]


Low Adhesive Surfaces that Adapt to Changing Environments

ADVANCED MATERIALS, Issue 18 2009
Roman Sheparovych
A responsive/adaptive nonadhesive surface coating that combines hydrophobic particles and hydrophilic polymer chains in a tethered composite coating is demonstrated. Rigid particles provide low contact area, while a selective segregation of polymer chains upon changing the surrounding environment from vapors to liquids and vice versa adapts the low-adhesive property of the composite surface. [source]


Relationship between ambient temperature and heat flux in the scrotal skin

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 4 2009
G.-S. Song
Summary Excessive scrotal heating or cooling may lead to the cessation of spermatogenesis. Data regarding heat exchange rates in scrotal skin can be used to control testicular temperature within the appropriate range. Heat flux (HF) in the scrotal skin surface is generated based on the surrounding environment. This study aims to elucidate the HF of scrotal skin by varying ambient temperature. Twenty college students including seven varicoceles volunteered as the subjects (mean age: 22.95 ± SD 1.96 years; height: 175.00 ± 5.17 cm; weight: 68.40 ± 8.65 kg; body mass index: 22.28 ± 2.15), and participated in the experiments from September 11 to October 4, 2006. The environmental temperature was controlled at 20 °C and 25 °C in the first and second experiment respectively. The HF and skin temperature on both sides of the scrotal surface were measured for 60 min in the environmental chamber. The results revealed that the HF was 87.64 ± 12.69 W/m2 and 78.91 ± 12.09 W/m2 in the left and right side of the scrotum respectively. The scrotal skin temperature (SST) was 30.28 ± 0.75 °C and 30.24 ± 0.62 °C on the left and right side of the scrotum in the 20 °C environment respectively. In the 25 °C environment the HF was 53.54 ± 8.86 W/m2 and 45.25 ± 8.32 W/m2, and the SST was 32.29 ± 0.61 °C and 32.07 ± 0.36 °C on the left and right side of the scrotum respectively. The cooling source power to decrease testicular temperature is suggested at 290 W/m2. This suggested value could be adopted a cooling device as clinical therapy for a heat stress patient to decrease testicular temperature affecting spermatogenesis. [source]


Air temperature effect on spray evaporation in sprinkler irrigation,

IRRIGATION AND DRAINAGE, Issue 4 2002
Dr Giulio Lorenzini
évaporation aérienne; irrigation par arroseur; équipement expérimental Abstract The temperature effect of the surrounding environment on mean steady aerial water evaporation in sprinkler irrigation is investigated. An experimental set-up was designed and built to work at opportune operating conditions holding all the other variables constant to minimise the experimental error. One hundred and thirty-seven tests were performed for this work, of which 81 were considered valid for a statistical analysis of the data measured. Evaporation ranged from 4.15 to 7.73% as the air temperature varied from 21.0 to 27.0° C. Results show a clear dependence of sprinkler water evaporation on air temperature with a logarithmic relation. Further investigations will examine broader temperature intervals to improve the assessment and will consider the effects due to other parameters affecting the phenomenon. Copyright © 2002 John Wiley & Sons, Ltd. Résumé Les effets de la température de l'environnement sur l'irrigation par arroseur ont été examinés. Un eq,uipement expérimental a été conçu et créé pour fonctionner dans des conditions d'emploi propices, et on a travaillé aussi pour tenir les autres variables le plus possible constantes pour minimiser l'erreur expérimentale. On a réalisé 137 tests et seulement 81 ont été considérés bons pour l'analyse statistique. On a vu que l'évaporation change de 4.15 à 7.73 pour cent avec le changement de température de 21.0 à 27.0° C. Les résultats montrent une claire dépendance logarithmique de l'évaporation avec la température de l'air. On propose dans le futur d'étendre l'intervalle des températures pour confirmer les résultats déjà vus et aussi de tester les influences d'autres variables d'intérêt pour ce phénomène. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Prevalence of verotoxin-producing Escherichia coli (VTEC) and E. coli O157:H7 in French pork

JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2002
J. Bouvet
Aims:,To determination the prevalence of VTEC in pork products and the surrounding environment of the pork plant (slaughterhouse and cutting plant), and characterization of the VTEC strains isolated (virulence genes and serotype). Methods and Results: ,Among the 2146 carcass and pork samples and 876 environmental samples (swabs of surfaces or materials), 328 (15%) and 170 (19%) were PCR-positive for stx genes respectively. VTEC strains were recovered from positive samples by colony hybridization or immunoconcentration, serotyped and genetically characterized. Strains of E. coli O157:H7 were not isolated from 3 uidA-positive samples detected by PCR. The VTEC isolates did not harbour eae, ehx and uidA genes. Conclusions: ,Pigs and pork meat may contain VTEC strains but characterization of the strains based on virulence factors showed that the potential danger of pork meat appears to be low since although all strains harboured a stx gene, they did not have other virulence genes. Significance and Impact of the Study:,General hygiene measures appear to be sufficient and specific hygiene measures for VTEC are not necessary at this time. The porcine VTEC strains isolated in our study probably do not present a hazard. [source]


Exploring the relationship between skin property and absorbent pad environment

JOURNAL OF CLINICAL NURSING, Issue 11 2009
Yoshie Shigeta
Aim., The aim of this study is to identify the related factors of skin lesions found in the surrounding environment of absorbent pads by clinical investigation. Background., Most older patients with incontinence use absorbent products, therefore causing many patients to have skin lesion in the absorbent pad area. To prevent these skin lesions from occurring, it is necessary to examine the absorbent pad environment of clinical patients since there are many contributing factors that complicate the pathophysiology in this area. Design., A cross-sectional design was used. Methods., One hundred older Japanese patients with faecal and/or urinary incontinence using diapers and absorbent pads participated. Excluding blanchable erythema, the presence of skin lesions in the absorbent pad area was confirmed. Skin pH, hydration level and bacterial cultures were used to assess the skin property. Absorbent pad environment and patient demographics were also investigated. Results., The overall prevalence of skin lesions was 36%. Forty percent of the skin lesions were contact dermatitis. Multivariate logistic regression analysis revealed that only the presence of diarrhoea independently affected contact dermatitis. Conclusion., There was a significant relationship between contact dermatitis and the use of absorbent pads when the patient had diarrhoea. Although the factors related to skin lesions in the absorbent pad area are complexly intertwined, this study was the first to be able to determine diarrhoea as one specific factor in clinical setting. Relevance to clinical practice., This finding suggests that the presence of diarrhoea is significantly related with contact dermatitis. Therefore, when a patient has diarrhoea, health-care professionals should immediately implement a preventative care program which includes careful skin observation and improved skin care. It is also necessary to develop a more effective absorbent pad to protect the skin of incontinent patients who suffer from the irritating effects of liquid stool. [source]


Initial Crisis Agent-Response Impact Syndrome (ICARIS)

JOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 4 2006
Tobin Hensgen
There has been a dramatic shift in attitude among organizations regarding the probabilities of crisis occurring. Once crises were considered the domain of the contingency management team that sought the fastest means to recovery, now the entire organization is compelled to take steps intended to mitigate conditions leading to a crisis. In this paper, the authors consider the organization's ,first responders' i.e., those who become involuntarily placed in the decision making process because they are the first to become aware of the conditions which indicate impending crisis simply because they are ,on scene.' As agents of the organization, these persons will make initial decisions well before the implementation of any formal contingency plan and because their decisions will be based on incomplete assumptions, they are likely to be in error. The impact of these initial crisis-agent responses can cause irreparable damage to the organization, to the individuals within the organization, and to the surrounding environment. This tendency toward error is referred to as the initial crisis-agent response impact syndrome: ICARIS. Exercising a program that prepares all employees for the initial decisions that need to be made at the moment of crisis can mitigate problems related to this issue. [source]


Pathogen fitness components and genotypes differ in their sensitivity to nutrient and temperature variation in a wild plant,pathogen association

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007
A.-L. LAINE
Abstract Understanding processes maintaining variation in pathogen life-history stages affecting infectivity and reproduction is a key challenge in evolutionary ecology. Models of host,parasite coevolution are based on the assumption that genetic variation for host,parasite interactions is a significant cause of variation in infection, and that variation in environmental conditions does not overwhelm the genetic basis. However, surprisingly little is known about the stability of genotype,genotype interactions under variable environmental conditions. Here, using a naturally occurring plant,pathogen interaction, I tested whether the two distinct aspects of the infection process , infectivity and transmission potential , vary over realistic nutrient and temperature gradients. I show that the initial pathogen infectivity and host resistance responses are robust over the environmental gradients. However, for compatible responses there were striking differences in how different pathogen life-history stages and host and pathogen genotypes responded to environmental variation. For some pathogen genotypes even slight changes in temperature arrested spore production, rendering the developing infection ineffectual. The response of pathogen genotypes to environmental gradients varied in magnitude and even direction, so that their rankings changed across the abiotic gradients. Hence, the variable environment of spatially structured host,parasite interactions may strongly influence the maintenance of polymorphism in pathogen life-history stages governing transmission, whereas evolutionary trajectories of infectivity may be unaffected by the surrounding environment. [source]


A possible molecular mechanism of hanatoxin binding-modified gating in voltage-gated K+ -channels

JOURNAL OF MOLECULAR RECOGNITION, Issue 6 2003
Kuo-Long Lou
Abstract While S4 is known as the voltage sensor in voltage-gated potassium channels, the carboxyl terminus of S3 (S3C) is of particular interest concerning the site for gating modifier toxins like hanatoxin. The thus derived helical secondary structural arrangement for S3C, as well as its surrounding environment, has since been intensively and vigorously debated. Our previous structural analysis based on molecular simulation has provided sufficient information to describe reasonable docking conformation and further experimental designs (Lou et al., 2002. J. Mol. Recognit. 15: 175,179). However, if one only relies on such information, more advanced structure,functional interpretations for the roles S3C may play in the modification of gating behavior upon toxin binding will remain unknown. In order to have better understanding of the molecular details regarding this issue, we have performed the docking simulation with the S3C sequence from the hanatoxin-insensitive K+ -channel, shaker, and analyzed the conformational changes resulting from such docking. Compared with other functional data from previous studies with respect to the proximity of the S3,S4 linker region, we suggested a significant movement of drk1 S3C, but not shaker S3C, in the direction presumably towards S4, which was comprehended as a possible factor interfering with S4 translocation during drk1 gating in the presence of toxin. In combination with the discussions for structural roles of the length of the S3,S4 linker, a possible molecular mechanism to illustrate the hanatoxin binding-modified gating is proposed. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Confocal microscopy of the light organ crypts in juvenile Euprymna scolopes reveals their morphological complexity and dynamic function in symbiosis

JOURNAL OF MORPHOLOGY, Issue 5 2006
Laura K. Sycuro
Abstract In the hours to days following hatching, the Hawaiian bobtail squid, Euprymna scolopes, obtains its light-emitting symbiont, Vibrio fischeri, from the surrounding environment and propagates the bacteria in the epithelial crypts of a specialized light organ. Three-dimensional analyses using confocal microscopy revealed that each of the three crypts on either side of the juvenile light organ is composed of four morphological regions. Progressing from the lateral pore to the medial blind end of each crypt, the regions consist of 1) a duct, 2) an antechamber, 3) a bottleneck, and 4) a deep region. Only the deep region houses a persistent bacterial population, whereas the duct, antechamber, and bottleneck serve as conduits through which the bacteria enter during initial colonization and exit during diel venting, a behavior in which ,90% of the symbionts are expelled each dawn. Our data suggest that, like the duct, the antechamber and bottleneck may function to promote and maintain the specificity of the symbiosis. Pronounced structural and functional differences among the deep regions of the three crypts, along with previously reported characterizations of embryogenesis, suggest a continued developmental progression in the first few days after hatching. Taken together, the results of this study reveal a high degree of complexity in the morphology of the crypts, as well as in the extent to which the three crypts and their constituent regions differ in function during the early stages of the symbiosis. J. Morphol. © 2006 Wiley-Liss, Inc. [source]


Alcohol Consumption, Alcohol Outlets, and the Risk of Being Assaulted With a Gun

ALCOHOLISM, Issue 5 2009
Charles C. Branas
Background:, We conducted a population-based case,control study to better delineate the relationship between individual alcohol consumption, alcohol outlets in the surrounding environment, and being assaulted with a gun. Methods:, An incidence density sampled case,control study was conducted in the entire city of Philadelphia from 2003 to 2006. We enrolled 677 cases that had been shot in an assault and 684 population-based controls. The relationships between 2 independent variables of interest, alcohol consumption and alcohol outlet availability, and the outcome of being assaulted with a gun were analyzed. Conditional logistic regression was used to adjust for numerous confounding variables. Results:, After adjustment, heavy drinkers were 2.67 times as likely to be shot in an assault when compared with nondrinkers (p < 0.10) while light drinkers were not at significantly greater risk of being shot in an assault when compared with nondrinkers. Regression-adjusted analyses also demonstrated that being in an area of high off-premise alcohol outlet availability significantly increased the risk of being shot in an assault by 2.00 times (p < 0.05). Being in an area of high on-premise alcohol outlet availability did not significantly change this risk. Heavy drinkers in areas of high off-premise alcohol outlet availability were 9.34 times (p < 0.05) as likely to be shot in an assault. Conclusions:, This study finds that the gun assault risk to individuals who are near off-premise alcohol outlets is about the same as or statistically greater than the risk they incur from heavy drinking. The combination of heavy drinking and being near off-premise outlets resulted in greater risk than either factor alone. By comparison, light drinking and being near on-premise alcohol outlets were not associated with increased risks for gun assault. Cities should consider addressing alcohol-related factors, especially off-premise outlets, as highly modifiable and politically feasible approaches to reducing gun violence. [source]


Thrombin induces neoangiogenesis in the chick chorioallantoic membrane

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2003
M. Caunt
Summary., Most tumors have constitutively active tissue factor on their surface, capable of generating thrombin in the surrounding environment, and thrombosis is associated with cancer. Thrombin is known to induce a malignant phenotype by enhancing tissue adhesion and cell growth in vitro and in vivo in mice. Because tumors require angiogenesis for growth, we examined whether thrombin induces neoangiogenesis in a physiologically intact in vivo model. Thrombin (0.1 U mL,1) induced neoangiogenesis in the chick chorioallantoic membrane over a 24,72-h period by approximately 2,3-fold. This was inhibited by the potent thrombin inhibitor, hirudin and shown to have its mode of action by ligation of the thrombin protease-activated receptor, PAR-1. The thrombin receptor activation peptide, SFLLRNPNDKYEPF (200 µm) also enhanced neoangiogenesis c. 2,3-fold. Thrombin-induced neoangiogenesis was accompanied by the induction of vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) mRNA at 24,48 h (approximately 2-fold) as determined by semi-quantitative reverse transcriptase-polymerase chain reaction. Thrombin-induced neoangiogenesis was inhibited to baseline level by the specific angiogenesis receptor inhibitors KDR-Fc (vs. VEGF) and Tie-2-Fc (vs. Ang-1 and Ang-2), as well as the non-specific angiogenesis inhibitor thrombospondin-1. Thrombin-induced neoangiogenesis was also inhibited to baseline level by agents known to inhibit thrombin receptor signaling in other cells: G-coupled protein receptor inhibitor, pertussis toxin (40 pg per egg), protein kinase C inhibitor, bisindolylmaleimide (1 µm per egg), MAP kinase inhibitor, PD980598 (10 µm per egg) and PI3 kinase inhibitor, LY294002 (0.25 µm per egg). Thus angiogenesis is stimulated by thrombosis, which could help explain the enhancement of experimental tumorigenesis by thrombin. [source]


A disc brake test stand for measurement of airborne wear particles

LUBRICATION SCIENCE, Issue 6 2009
Jens Wahlström
Abstract During braking, there is wear on both the rotor and the pads. This process generates particles that may become airborne. In field tests, it is difficult to distinguish these particles from others in the surrounding environment. Therefore, a laboratory test stand has been designed which allows control of the cleanliness of the surrounding air. The test stand consists of a front right brake assembly mounted in a sealed chamber. A braking load is applied by a pneumatic system and the rotor, which has been pre-conditioned with a rust layer to simulate a car standing parked overnight in a wet environment, is driven by an electric motor. The number and size of airborne wear particles are then measured. This experimental set-up has been verified by an initial test series performed at low braking loads. The results suggest that this test stand can be used to study rust layer removal from the rotor. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Novel pH- and Temperature-Responsive Methacrylamide Microgels,

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13-14 2009
Leyre Pérez-Álvarez
Abstract A novel transition temperature in MeAM copolymer microgels is reported. Despite the fact that MeAM homopolymers do not show thermosensitive properties, a specific synthetic strategy leads to a thermo-responsive swelling behavior that could be potentially useful in medical and/or industrial applications. The pH and temperature-dependent swelling response of microgels of MeAM copolymerized with 2-aminomethylpyridine and ethylenediamine is reported. The changes in particle sizes, which depend on the nature of the surrounding environment, are recorded by QELS. The relation between copolymer structure and its novel behavior is analyzed by several techniques (1H NMR, TGA). [source]


Lipid bilayers: an essential environment for the understanding of membrane proteins

MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2007
Richard C. Page
Abstract Membrane protein structure and function is critically dependent on the surrounding environment. Consequently, utilizing a membrane mimetic that adequately models the native membrane environment is essential. A range of membrane mimetics are available but none generates a better model of native aqueous, interfacial, and hydrocarbon core environments than synthetic lipid bilayers. Transmembrane ,-helices are very stable in lipid bilayers because of the low water content and low dielectric environment within the bilayer hydrocarbon core that strengthens intrahelical hydrogen bonds and hinders structural rearrangements within the transmembrane helices. Recent evidence from solid-state NMR spectroscopy illustrates that transmembrane ,-helices, both in peptides and full-length proteins, appear to be highly uniform based on the observation of resonance patterns in PISEMA spectra. Here, we quantitate for the first time through simulations what we mean by highly uniform structures. Indeed, helices in transmembrane peptides appear to have backbone torsion angles that are uniform within ± 4° . While individual helices can be structurally stable due to intrahelical hydrogen bonds, interhelical interactions within helical bundles can be weak and nonspecific, resulting in multiple packing arrangements. Some helical bundles have the capacity through their amino acid composition for hydrogen bonding and electrostatic interactions to stabilize the interhelical conformations and solid-state NMR data is shown here for both of these situations. Solid-state NMR spectroscopy is unique among the techniques capable of determining three-dimensional structures of proteins in that it provides the ability to characterize structurally the membrane proteins at very high resolution in liquid crystalline lipid bilayers. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Variability in the nutritional value of the major copepods in Cape Cod Bay (Massachusetts, USA) with implications for right whales

MARINE ECOLOGY, Issue 2 2006
Amy DeLorenzo Costa
Abstract The North Atlantic right whale, a seriously endangered species, is found in Cape Cod Bay (Massachusetts, USA) during the winter and early spring. During their residency in these waters, these whales are frequently observed feeding. This study evaluated spatial and temporal changes in the chemical composition (carbon weight and C/N ratio) of the food resource targeted by the right whales in Cape Cod Bay. The three taxa measured (Centropages typicus, Pseudocalanus spp., and Calanus finmarchicus) had highly variable chemical compositions resulting from the different life strategies and from fluctuations in their surrounding environment. The impact of seasonal variability in the energy densities of the food resource of right whales was calculated and compared to the energetic requirements of these whales. Calculations indicated that differences in the nutritional content of the zooplankton prey in Cape Cod Bay could have a considerable effect on the nutrition available to the right whales. Therefore, it is likely that using more precise estimates of the energetic densities of the prey of right whales would lead to a re-evaluation of the adequacy of the food resource available to these whales in the North Atlantic. [source]


Sialidase of Streptococcus intermedius: a putative virulence factor modifying sugar chains

MICROBIOLOGY AND IMMUNOLOGY, Issue 10 2010
Ayuko Takao
ABSTRACT A sialidase gene of Streptococcus intermedius was cloned. It was most similar to nanA, a major sialidase gene in Streptococcus pneumoniae, and was expressed in Escherichia coli. Since the gene-knockout S. intermedius strain lost detectable sialidase activity, the gene might code, either solely or mainly, the glycosidase in the bacterial genome. Polymerase chain reaction using the primers for the nanA homologue in S. intermedius (described as nanA below) showed that this sialidase gene was commonly distributed within the isolates of S. intermedius, but not found in the strains of other species among the anginosus group. In biofilm formation assay under cultivation with mucin, the nanA -deleted S. intermedius maintained the amount of biofilm for 72 hr, while that of the parent strain decreased during incubation from 24 to 72 hr. Since sialidase activity in the parent strain increased during that time period, sialidase might contribute to the degradation of biofilm under sialic acid-rich conditions. When S. intermedius was added into the HepG2 hepatoma culture, the calculated disassociation constant (Kd) of EDTA-releasable bacterial adhesion to the cells was higher in the nanA -deleted strain than in the parent. Furthermore, the rate constant, assuming endocytosis of the bacterium mediated by ASGP-R in HepG2 cells, seemed to be increased by sialidase pretreatment of the bacterial cells before addition to the cell culture. According to the results, modification of sugar chains by sialidase on the bacterial surface and in the surrounding environment might influence both bacterial interaction and host,bacterial interaction in S. intermedius. [source]


Micro-fabrication and monitoring of three-dimensional microstructures based on laser-induced thermoplastic formation

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 10 2009
Leyan Wang
Abstract This article reports a novel laser-induced micro-fabrication method and its monitoring system for three-dimensional (3D) microstructures. The mechanism of the method is that a small zone of thermoplastic material melted by laser heating grows in liquid surrounding environment, solidifying into a convex microstructure, such as micro-dot or micro-pillar. A laser diode (808 nm) with maximum power output of 130 mW is used as power source, and a kind of paraffin mixed with stearic acid and paint serves as the thermoplastic material for 3D microstructure formation experiments. A light microscope system consisting of a charge-coupled device (CCD) and a computer is utilized to realize real-time observation of the micro-fabricating process. The distribution of local temperature rise on material surface created by laser irradiation is simulated. The effects of liquid environment on microstructure formation have been theoretically analyzed and experimentally studied. Experiments are further carried out to investigate the relationship between laser spot and fabricated microstructures. The results indicate that the widths of micro-dots or micro-pillars are mostly determined by the size of focal spot, and their heights increase with the enlargement of laser power density. With this method, a micro-dot array of Chinese characters meaning "China" has been successfully fabricated through computer programming. This method has the advantages of implementing direct, mask-less, real-time and inexpensive 3D microstructure fabrication. Therefore, it would be widely applied in the fields of micro/nano-technology for practical fabrication of different kinds of 3D microstructures. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source]


The properties of the heterogeneous Shakhbazyan groups of galaxies in the SDSS

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009
D. Capozzi
ABSTRACT We present a systematic study of the subsample of Shakhbazyan (SHK) groups covered by the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). SHK groups probe an environment with characteristics which are intermediate between those of loose and very compact groups. Surprisingly, we found that several groups identifying algorithms, e.g. Berlind et al. and Tago et al., miss this type of structures. Using the SDSS DR5 spectroscopic data and the photometric redshifts derived in D'Abrusco et al., we identified possible group members in photometric redshift space and derived, for each group, several individual properties (richness, size, mean photometric redshift, fraction of red galaxies, etc.). We also combined pointed and stacked Rosat All Sky Survey (RASS) data to investigate the X-ray luminosities of these systems. Our study confirms that the majority of groups are physical entities with richness in the range 3,13 galaxies, and properties ranging between those of loose and compact groups. We confirm that SHK groups are richer in early-type galaxies than the surrounding environment and the field, as expected from the morphology,density relation and from the selection of groups of red galaxies. Furthermore, our work supports the existence of two subclasses of structures, the first one being formed by compact and isolated groups and the second formed by extended structures. We suggest that while the first class of objects dwells in less dense regions like the outer parts of clusters or the field, possibly sharing the properties of Hickson Compact Groups, the more extended structures represent a mixture of [core + halo] configurations and cores of rich clusters. X-ray luminosities for SHK groups are generally consistent with these results and with the expectations for the LX,,v relation, but also suggest the velocity dispersions reported in literature are underestimated for some of the richest systems. [source]


AlGaN/GaN-based MEMS with two-dimensional electron gas for novel sensor applications

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
F. Niebelschütz
Abstract Novel microelectromechanical resonators structures have been realized based on AlGaN/GaN heterostructures, which provide a basis for sophisticated sensor structures. There were grown on SiC substrates confining a two dimensional electron gas (2DEG). By means of the developed etching technology, freestanding resonators were patterned without degrading the sheet carrier concentration and electron mobility of the 2DEG inside the beams, which was confirmed by electrical measurements before and after the various process steps. As actuation and read out principle magnetomotive and piezoelectric effects were used, respectively. Due to the high sensitivity of the 2DEG and the chemical stability of the utilized materials these structures are suitable for chemical and biological sensor applications, where the sensitivity of the 2DEG on the surrounding environment acts as additional sensing signal, for example for simultaneous measurements of the viscosity and pH , value of a nanoliter droplet. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Numerical investigations on autogenous shrinkage of cement paste and mortar

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009
Thorsten Leusmann
Autogenous shrinkage of cement paste and concrete is defined as the macroscopic length change occurring with no moisture transferred to the exterior surrounding environment. It is a result of chemical shrinkage affiliated with the hydration of cement particles and the ongoing process of self-desiccation. The process of self-desiccation can be modeled starting from the formation of the capillary pore space during hydration in the cement paste. In this proposal a working model will be introduced explaining the difficulties to obtain the autogenous shrinkage strains directly from a simulated or measured microstructure of cement paste. In a second step the autogenous shrinkage of a hardening cement mortar was described on a mesoscopic level. It based on measurements on cement paste. The mortar simply consists of cement paste and a defined fraction of spherical aggregates with a known modulus of elasticity. Furthermore the influence of the interfacial transition zone (ITZ) is studied in numerical simulations. The results of these finite-element-calculations are introduced and compared with testing results of the autogenous shrinkage of hardening mortar samples. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Folding and binding cascades: Dynamic landscapes and population shifts

PROTEIN SCIENCE, Issue 1 2000
Sandeep Kumar
Abstract Whereas previously we have successfully utilized the folding funnels concept to rationalize binding mechanisms (Ma B, Kumar S, Tsai CJ, Nussinov R, 1999, Protein Eng 12:713,720) and to describe binding (Tsai CJ, Kumar S, Ma B, Nussinov R, 1999, Protein Sci 8:1181,1190), here we further extend the concept of folding funnels, illustrating its utility in explaining enzyme pathways, multimolecular associations, and allostery. This extension is based on the recognition that funnels are not stationary; rather, they are dynamic, depending on the physical or binding conditions (Tsai CJ, Ma B, Nussinov R, 1999, Proc Natl Acad Sci USA 96:9970,9972). Different binding states change the surrounding environment of proteins. The changed environment is in turn expressed in shifted energy landscapes, with different shapes and distributions of populations of conformers. Hence, the function of a protein and its properties are not only decided by the static folded three-dimensional structure; they are determined by the distribution of its conformational substates, and in particular, by the redistributions of the populations under different environments. That is, protein function derives from its dynamic energy landscape, caused by changes in its surroundings. [source]