Home About us Contact
|
Home About us Contact | ||
|
|
||
Complex Set (complex + set)
Selected AbstractsThe regulation of muscle glycogen: the granule and its proteinsACTA PHYSIOLOGICA, Issue 4 2010T. E. Graham Abstract Despite decades of studying muscle glycogen in many metabolic situations, surprisingly little is known regarding its regulation. Glycogen is a dynamic and vital metabolic fuel that has very limited energetic capacity. Thus its regulation is highly complex and multifaceted. The stores in muscle are not homogeneous and there appear to be various metabolic pools. Each granule is capable of independent regulation and fundamental aspects of the regulation appear to be associated with a complex set of proteins (some are enzymes and others serve scaffolding roles) that associate both with the granule and with each other in a dynamic fashion. The regulation includes altered phosphorylation status and often translocation as well. The understanding of the roles and the regulation of glycogenin, protein phosphatase 1, glycogen targeting proteins, laforin and malin are in their infancy. These various processes appear to be the mechanisms that give the glycogen granule precise, yet dynamic regulation. [source] Climate Variability in Regions of Amphibian DeclinesCONSERVATION BIOLOGY, Issue 4 2001Michael A. Alexander The reanalysis system merges observations from airplanes, land stations, satellites, ships, and weather balloons with output from a weather-forecast model to create global fields of atmospheric variables. Station data consisted of temperature and precipitation measured with thermometers and rain gauges at fixed locations. Temperatures were near normal in Colorado when the amphibian declines occurred in the 1970s, whereas in Central America temperatures were warmer than normal, especially during the dry season. The station data from Puerto Rico and Australia indicated that temperatures were above normal during the period of amphibian declines, but reanalysis did not show such a clear temperature signal. Although declines occurred while the temperature and precipitation anomalies in some of the regions were large and of extended duration, the anomalies were not beyond the range of normal variability. Thus, unusual climate, as measured by regional estimates of temperature and precipitation, is unlikely to be the direct cause of amphibian declines, but it may have indirectly contributed to them. Previous researchers have noted that the declines appear to have propagated from northwest to southeast from Costa Rica to Panama and from southeast to northwest in Queensland, Australia. Wind has the potential to transport pathogens that cause amphibian mortality. The mean direction of the near-surface winds tended to parallel the path of amphibian declines from July,October in Central America and from May,July in Australia. The wind direction was highly variable, however, and the propagation rate of amphibian declines was much slower than the mean wind speed. In addition, the most likely pathogen is a chytrid fungus that does not produce desiccation-resistant spores. Thus, if wind is involved in the propagation of amphibian declines, it is through a complex set of processes. Resumen: Exploramos la relación entre las declinaciones de anfibios y las variaciones climáticas en Colorado, E.U.A., Puerto Rico, Costa Rica/Panamá y Queensland, Australia por medio de dos fuentes de información: resultados "sistema de reanálisis" del Centro Nacional de Predicción Ambiental y datos de estaciones área-promedio. El sistema de reanálisis combina observaciones de aeroplanos, estaciones terrestres, satélites, barcos y globos climatológicos, con resultados de un modelo de predicción climatológica para crear campos globales de variables atmosféricas. Los datos de estaciones fueron de temperatura y precipitación medidos con termómetros y pluviómetros en localidades fijas. Las temperaturas fueron casi normales en Colorado cuando ocurrieron las declinaciones en la década de 1970, mientras que las temperaturas en Centro América fueron mayores a lo normal, especialmente durante la época de sequía. Los datos de estaciones en Puerto Rico y Australia indicaron que la temperatura fue mayor a la normal durante el período de declinación de anfibios, pero un nuevo análisis no mostró una señal de temperatura tan clara. Aunque las declinaciones ocurrieron mientras las anomalías de temperatura y precipitación fueron grandes y de duración prolongada en algunas de las regiones, las anomalías no rebasaron el rango de variabilidad normal. Por lo tanto, es poco probable que el clima inusual, medido por estimaciones regionales de temperatura y precipitación, sea la causa directa de las declinaciones de anfibios, pero pudo haber contribuido indirectamente a ellas. Investigaciones previas notan que las declinaciones parecen haberse propagado de noroeste a sureste de Costa Rica a Panamá y de sureste a noreste en Queensland, Australia. El viento tiene el potencial de transportar patógenos que causan mortalidad de anfibios. La dirección promedio de los vientos superficiales tendió a ser paralela al camino de las declinaciones de anfibios de julio a octubre en Centro América y de mayo a julio en Australia. Sin embargo, la dirección del viento fue altamente variable y la tasa de propagación de declinaciones de anfibios fue mucho más lenta que la velocidad promedio del viento. Adicionalmente, el patógeno más probable es un hongo quítrido que no produce esporas resistentes a la desecación. Por tanto, si el viento está implicado en la propagación de declinaciones de anfibios, lo es por medio de un complejo conjunto de procesos. [source] Brachyury -downstream notochord genes and convergent extension in Ciona intestinalis embryosDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2007Kohji Hotta Formation of the chordate body is accomplished by a complex set of morphogenetic movements including convergent extension of notochord cells. In the ascidian Ciona intestinalis, Brachyury plays a key role in the formation of the notochord, and more than 30 Bra-downstream notochord genes have been identified. In the present study, we examined the effects of functional suppression of nine Bra -downstream notochord genes, which include Ci-PTP, Ci-ACL, Ci-prickle, Ci-netrin, Ci-trop, Ci-Noto3, Ci-ASAK, Ci-ERM and Ci-pellino. When the function of the first two genes (Ci-PTP and Ci-ACL) was suppressed with specific morpholinos, the notochord cells failed to converge, while functional suppression of Ci-prickle resulted in a failure of intercalation, and therefore the cells in these three types of embryo remained in the mid-dorsal region of the embryo. Functional suppression of the next four genes (Ci-netrin, Ci-trop, Ci-Noto3 and Ci-ASAK) resulted in the partial defect of intercalation, and the notochord did not consist of a single row. In addition, when the function of the last two genes (Ci-ERM and Ci-pellino) was suppressed, notochord cells failed to elongate in the embryo, even though convergence/extension took place normally. These results indicate that many Bra -downstream notochord genes are involved in convergence/extension of the embryo. [source] Development of swallowing and feeding: Prenatal through first year of lifeDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 2 2008Amy L. Delaney Abstract The development of feeding and swallowing involves a highly complex set of interactions that begin in embryologic and fetal periods and continue through infancy and early childhood. This article will focus on swallowing and feeding development in infants who are developing normally with a review of some aspects of prenatal development that provide a basis for in utero sucking and swallowing. Non-nutritive sucking in healthy preterm infants, nipple feeding in preterm and term infants, and selected processes of continued development of oral skills for feeding throughout the first year of life will be discussed. Advances in research have provided new information in our understanding of the neurophysiology related to swallowing, premature infants' sucking and swallowing patterns, and changes in patterns from preterm to near term to term infants. Oral skill development as texture changes are made throughout the second half of the first year of life is an under studied phenomenon. Knowledge of normal developmental progression is essential for professionals to appreciate differences from normal in infants and children with feeding and swallowing disorders. Additional research of infants and children who demonstrate overall typical development in oral skills for feeding is encouraged and will provide helpful reference points in increasing understanding of children who exhibit differences from typical development. It is hoped that new technology will provide noninvasive means of delineating all phases of sucking and swallowing from prenatal through infancy. Further related topics in other articles of this issue provide a comprehensive review of factors influencing oral intake, growth, nutrition, and neurodevelopmental status of children. © 2008 Wiley-Liss, Inc. Dev Disabil Res Rev 2008;14:105,117. [source] Phylogeny of the teashirt-related zinc finger (tshz) gene family and analysis of the developmental expression of tshz2 and tshz3b in the zebrafishDEVELOPMENTAL DYNAMICS, Issue 3 2010Joana S. Santos Abstract The tshz genes comprise a family of evolutionarily conserved transcription factors. However, despite the major role played by Drosophila tsh during the development of the fruit fly, the expression and function of other tshz genes have been analyzed in a very limited set of organisms and, therefore, our current knowledge of these genes is still fragmentary. In this study, we perform detailed phylogenetic analyses of the tshz genes, identify the members of this gene family in zebrafish and describe the developmental expressions of two of them, tshz2 and tshz3b, and compare them with meis1, meis2.1, meis2.2, pax6a, and pax6b expression patterns. The expression patterns of these genes define a complex set of coexpression domains in the developing zebrafish brain where their gene products have the potential to interact. Developmental Dynamics 239:1010,1018, 2010. © 2010 Wiley-Liss, Inc. [source] A new interpretation of the female genitalia in Macrocyclops albidus (Copepoda, Cyclopidae)ACTA ZOOLOGICA, Issue 1 2003D. Defaye Abstract The female genital structures of Macrocyclops albidus (Cyclopidae, Eucyclopinae) were studied using light and electron microscopy. The results confirm that the exterior genital area shows only a copulatory pore, located anteromedially on the ventral face of the genital double-somite, and paired gonopores (not directly visible), situated laterally under the P6 plates. An internal seminal receptacle, composed of several parts, is connected to the gonopores by ventro-lateral cuticular extensions or seminal ducts. The lateral site of communication shows a complex set of connections between the seminal receptacle and the oviducts (via the egg-laying ducts). The structure until now designated as ,transverse ducts', visible by transparency on the ventral face, is in fact constituted of internal cuticular thickenings resulting of the fusion of the 6th thoracic somite and the 1st abdominal somite forming the genital double-somite and appearing externally as a part of the suture line; the term ,suture cord' is proposed to designate it. The functioning of the system is explained. [source] Seismic interaction in electrical substation equipment connected by non-linear rigid bus conductorsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2007Junho Song Abstract An important element within the power transmission lifeline is the electrical substation that typically consists of a complex set of equipment items interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic event, which may result in damage and loss of the equipment. This paper investigates the interaction effect between electrical substation equipment items connected by non-linear rigid bus conductors. The equipment items are modelled as single-degree-of-freedom oscillators by use of appropriate shape functions. The hysteretic behaviours of rigid bus connectors are described by differential equation models fitted to experimental data. An efficient non-linear random vibration method is used to quantify the seismic interaction effect of the connected equipment items. Based on the developed analytical models and method, the effect of interaction in the connected equipment system is investigated through extensive parametric studies. The results lead to practical charts and guidelines for the seismic design of interconnected electrical substation equipment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Seismic interaction in linearly connected electrical substation equipmentEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2001A. Der Kiureghian Abstract An electrical substation consists of a complex set of equipment items that are interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic excitation. This interaction is believed to be responsible for some of the observed substation equipment damage in recent earthquakes. This paper investigates the interaction between two equipment items connected by a linear spring-dashpot or spring-dashpot-mass element representing a conductor bus. It is found that the interaction between the two equipment items may significantly amplify the response of the higher-frequency equipment item. The influences of various key parameters on the interaction effect are quantified. Means for reducing the adverse interaction effect are described. Copyright © 2001 John Wiley & Sons, Ltd. [source] Homing in German Cockroaches, Blattella germanica (L.) (Insecta: Dictyoptera): Multi-Channelled Orientation CuesETHOLOGY, Issue 10 2004Colette Rivault Cockroaches use navigational cues to elaborate their return path to the shelter. Our experiments investigated how individuals weighted information to choose where to search for the shelter in situations where path integration, visual and olfactory cues were conflicting. We showed that homing relied on a complex set of environmental stimuli, each playing a particular part. Path integration cues give cockroaches an estimation of the position of their goal, visual landmarks guide them to that position from a distance, while olfactory cues indicate the end of the path. Cockroaches gave the greatest importance to the first cues they encountered along their return path. Nevertheless, visual cues placed beyond aggregation pheromone deposits reduced their arrest efficiency and induced search in the area near the visual cues. [source] Mobile phones, communities and social networks among foreign workers in SingaporeGLOBAL NETWORKS, Issue 3 2009ERIC C. THOMPSON Abstract Transnational mobility affects both high-status and low-income workers, disrupting traditional assumptions of the boundedness of communities. There is a need to reconfigure our most basic theoretical and analytical constructs. In this article I engage in this task by illustrating a complex set of distinctions (as well as connections) between ,communities' as ideationally constituted through cultural practices and ,social networks' constituted through interaction and exchange. I have grounded the analysis ethnographically in the experiences of foreign workers in Singapore, focusing on domestic and construction workers from the Philippines, Indonesia, Thailand and Bangladesh. I examine the cultural, social and communicative role that mobile phones play in the lives of workers who are otherwise constrained in terms of mobility, living patterns and activities. Mobile phones are constituted as symbol status markers in relationship to foreign workers. Local representations construct foreign workers as users and consumers of mobile telephony, reinscribing ideas of transnational identities as well as foreignness within the context of Singapore. Migrant workers demonstrate a detailed knowledge of the various telephony options available, but the desire to use phones to communicate can overwhelm their self-control and lead to very high expenditures. The research highlights the constraints , as well as possibilities , individuals experience as subjects and agents within both social and cultural systems, and the ways in which those constraints and possibilities are mediated by a particular technology , in this case, mobile phones. [source] Making healthy eating messages more effective: combining integrated marketing communication with the behaviour ecological modelINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 4 2006Emma Dresler-Hawke Abstract Encouraging healthy living involves a complex set of factors that interact with each other. Effective social communication strategies and conceptual models are needed in order to plan and maintain a desired level of societal change. More understanding is needed as to how different levels of society are affected by social communication messages. This paper examines how a social marketing strategy should be targeted in order to maximize societal change. In this paper the Multi-levelled/Multimedia Model of Social Change is presented. This amalgamates integrated marketing communication principles and the Behavioural Ecological Model. It provides a basis for understanding how consistent messages and methods of communication affect long-term behavioural or attitudinal change at the individual and societal levels. [source] Palaeopathological and palaeogenetic study of 13 cases of developmental dysplasia of the hip with dislocation in a historical population from southern FranceINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2007B. Mafart Abstract Dislocation of the hip can be consecutive to developmental dysplasia of the hip that is linked to a complex set of genetic and mechanical factors. The purpose of this report is to describe 13 cases of complete dysplastic hip dislocation observed in the skeletal remains of nine women exhumed from an historical gravesite dating from the 5th to 17th centuries in southern France. Despite the size of this palaeopathological series, which is the largest study published to date, findings indicate that the prevalence of hip dislocation in this historical sample was still lower than in some French areas at the beginning of the 20th century. Mitochondrial DNA sequencing demonstrated possible kinship only between two women, i.e. one who died in the period from the 11th to 13th centuries and another who died in the period from the 16th to 17th centuries. It is suggested that the tight swaddling of young infants in France up to the end of the 19th century could have been a predisposing factor for this highly debilitating disorder. Copyright © 2006 John Wiley & Sons, Ltd. [source] Identity Patterns among Immigrants from the Former Soviet Union in Israel: Assimilation vs.INTERNATIONAL MIGRATION, Issue 2 2002Ethnic Formation This paper deals with identity patterns among the 1990s immigrants from the former Soviet Union (FSU) in Israel. It presents the complex set of identity types among immigrants in the context of their cultural and socio-demographic characteristics and their dynamic relationships with the Israeli host society. The findings show that immigrants from the FSU in Israel form a distinct ethnic group within the Israeli social and cultural fabric. This is reflected in their closed social networks, ethnic information sources, strong desire to maintain ethnic-cultural continuity, and the fact that the ethnic component (Jew from the FSU or immigrant from the FSU) is central for self-identification. However, ethnic formation among these immigrants is not a reactive-oriented identity, which is mainly generated by alienation from the host society, it is rather an instrumentalized ethnicity, which is the outcome of ethnic-cultural pride and pragmatic considerations. [source] Predator functional response and prey survival: direct and indirect interactions affecting a marked prey populationJOURNAL OF ANIMAL ECOLOGY, Issue 1 2006DAVID A. MILLER Summary 1Predation plays an integral role in many community interactions, with the number of predators and the rate at which they consume prey (i.e. their functional response) determining interaction strengths. Owing to the difficulty of directly observing predation events, attempts to determine the functional response of predators in natural systems are limited. Determining the forms that predator functional responses take in complex systems is important in advancing understanding of community interactions. 2Prey survival has a direct relationship to the functional response of their predators. We employed this relationship to estimate the functional response for bald eagle Haliaeetus leucocepalus predation of Canada goose Branta canadensis nests. We compared models that incorporated eagle abundance, nest abundance and alternative prey presence to determine the form of the functional response that best predicted intra-annual variation in survival of goose nests. 3Eagle abundance, nest abundance and the availability of alternative prey were all related to predation rates of goose nests by eagles. There was a sigmoidal relationship between predation rate and prey abundance and prey switching occurred when alternative prey was present. In addition, predation by individual eagles increased as eagle abundance increased. 4A complex set of interactions among the three species examined in this study determined survival rates of goose nests. Results show that eagle predation had both prey- and predator-dependent components with no support for ratio dependence. In addition, indirect interactions resulting from the availability of alternative prey had an important role in mediating the rate at which eagles depredated nests. As a result, much of the within-season variation in nest survival was due to changing availability of alternative prey consumed by eagles. 5Empirical relationships drawn from ecological theory can be directly integrated into the estimation process to determine the mechanisms responsible for variation in observed survival rates. The relationship between predator functional response and prey survival offers a flexible and robust method to advance our understanding of predator,prey interactions in many complex natural systems where prey populations are marked and regularly visited. [source] Advanced glycation end products: a highly complex set of biologically relevant compounds detected by mass spectrometry,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2001Annunziata Lapolla Abstract Structural information on ,AGE-peptides,' a class of substances belonging to advanced glycation end products (AGE) and originating by proteolysis of glycated proteins, was gained through various analytical approaches on the mixture produced by proteinase K digestion of in vitro glycated bovine serum albumin. Both matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) were employed, and the results were compared with those from conventional spectroscopic methods (UV, fluorescence, gel permeation). The data acquired by the various techniques all depict the digestion mixtures as highly complex, with components exhibiting molecular mass in the range 300,3500 Da. In the analysis of HPLC/ESI-MS data, identification of AGE-peptides was facilitated by 3D mapping. Structural information was gained by means of multiple mass spectrometric experiments. Copyright © 2001 John Wiley & Sons, Ltd. [source] A novel prohormone processing site in Aplysia californica: the Leu,Leu ruleJOURNAL OF NEUROCHEMISTRY, Issue 6 2002Amanda B. Hummon Abstract Neuropeptides are a complex set of signaling molecules produced through enzymatic cleavages from longer prohormone sequences. The most common cleavage sites in prohormones are basic amino acid residues; however, processing is observed at non-basic sites. Cleavage at Leu,Leu sequences has been observed in three Aplysia californica prohormones. To further investigate this unusual event, native and non-native synthetic peptides containing Leu,Leu residues are incubated with homogenates of Aplysia californica ganglia and the resulting products monitored with MALDI MS. Cleavage near and between Leu,Leu residues is observed in the abdominal and buccal ganglia homogenates, confirming the presence of an unidentified peptidase. In addition, fractions from an HPLC separation of buccal ganglia homogenates also produce cleavages at Leu,Leu residues. Products resulting from cleavage at Leu,Leu sites are observed and are produced in larger amounts in acidic and neutral pH ranges, and cleavage is inhibited by the addition of EDTA, suggesting a metal is required for activity. [source] Ethanol Alters the Osteogenic Differentiation of Amniotic Fluid-Derived Stem CellsALCOHOLISM, Issue 10 2010Jennifer A. Hipp Background:, Fetal alcohol spectrum disorder (FASD) is a set of developmental defects caused by prenatal alcohol exposure. Clinical manifestations of FASD are highly variable and include mental retardation and developmental defects of the heart, kidney, muscle, skeleton, and craniofacial structures. Specific effects of ethanol on fetal cells include induction of apoptosis as well as inhibition of proliferation, differentiation, and migration. This complex set of responses suggests that a bioinformatics approach could clarify some of the pathways involved in these responses. Methods:, In this study, the responses of fetal stem cells derived from the amniotic fluid (AFSCs) to treatment with ethanol have been examined. Large-scale transcriptome analysis of ethanol-treated AFSCs indicates that genes involved in skeletal development and ossification are up-regulated in these cells. Therefore, the effect of ethanol on osteogenic differentiation of AFSCs was studied. Results:, Exposure to ethanol during the first 48 hours of an osteogenic differentiation protocol increased in vitro calcium deposition by AFSCs and increased alkaline phosphatase activity. In contrast, ethanol treatment later in the differentiation protocol (day 8) had no significant effect on the activity of alkaline phosphatase. Conclusions:, These results suggest that transient exposure of AFSCs to ethanol during early differentiation enhances osteogenic differentiation of the cells. [source] Broad-scale vegetation-environment relationships in Eurasian high-latitude areasJOURNAL OF VEGETATION SCIENCE, Issue 4 2006Risto Virtanen Hultén & Fries (1986); Ignatov & Afonina (1992); Konstantinova et al. (1992); Vitikainen et al. (1997) Abstract Question: How is tundra vegetation related to climatic, soil chemical, geological variables and grazing across a very large section of the Eurasian arctic area? We were particularly interested in broad-scale vegetation-environment relationships and how well do the patterns conform to climate-vegetation schemes. Material and Methods: We sampled vegetation in 1132 plots from 16 sites from different parts of the Eurasian tundra. Clustering and ordination techniques were used for analysing compositional patterns. Vegetation-environment relationships were analysed by fitting of environmental vectors and smooth surfaces onto non-metric multidimensional scaling scattergrams. Results: Dominant vegetation differentiation was associated with a complex set of environmental variables. A general trend differentiated cold and continental areas from relatively warm and weakly continental areas, and several soil chemical and physical variables were associated with this broad-scaled differentiation. Especially soil chemical variables related to soil acidity (pH, Ca) showed linear relationships with the dominant vegetation gradient. This was closely related to increasing cryoperturbation, decreasing precipitation and cooler conditions. Remarkable differences among relatively adjacent sites suggest that local factors such as geological properties and lemming grazing may strongly drive vegetation differentiation. Conclusions: Vegetation differentiation in tundra areas conforms to a major ecocline underlain by a complex set of environmental gradients, where precipitation, thermal conditions and soil chemical and physical processes are coupled. However, local factors such as bedrock conditions and lemming grazing may cause marked deviations from the general climate-vegetation models. Overall, soil chemical factors (pH, Ca) turned out to have linear relationship with the broad-scale differentiation of arctic vegetation. [source] Discovering new invertebrate neuropeptides using mass spectrometryMASS SPECTROMETRY REVIEWS, Issue 1 2006Amanda B. Hummon Abstract Neuropeptides are a complex set of messenger molecules controlling a wide array of regulatory functions and behaviors within an organism. These neuromodulators are cleaved from longer protein molecules and often experience numerous post-translational modifications to achieve their bioactive form. As a result of this complexity, sensitive and versatile analysis schemes are needed to characterize neuropeptides. Mass spectrometry (MS) through a variety of approaches has fueled the discovery of hundreds of neuropeptides in invertebrate species in the last decade. Particularly successful are direct tissue and single neuron analyses by matrix-assisted laser desorption/ionization (MALDI) MS, which has been used to elucidate approximately 440 neuropeptides, and examination of neuronal homogenates by electrospray ionization techniques (ESI), also leading to the characterization of over 450 peptides. Additional MS methods with great promise for the discovery of neuropeptides are MS imaging and large-scale peptidomics studies in combination with a sequenced genome. © 2005 Wiley Periodicals, Inc. [source] Kunyenga, "Real Sex," and Survival: Assessing the Risk of HIV Infection among Urban Street Boys in TanzaniaMEDICAL ANTHROPOLOGY QUARTERLY, Issue 3 2002Chris Lockhart This article examines possible avenues of HIV infection among urban street boys in Tanzania. In doing so, it questions the ways that AIDS researchers have defined and approached the phenomenon of "survival sex" in East and Central Africa. The article specifically examines the boys' sexual networks, sexual practices, and attitudes regarding their own sexual behavior, including their perceived risk of HIV/AIDS infection. Seventy-five street boys aged eight to 20 from the city ofMwanza were interviewed. Results suggest that almost all street boys are involved in a sexual network in which homosexual and heterosexual behavior occurs. Homosexual practices are rooted in a complex set of behaviors and ideologies known as kunyenga, which is a situated aspect of life on the streets and helps maintain the boys' strong dependence on one another. A key aspect of the boys' sexual careers involves a decrease in kunyenga activity as they approach the age of 18 and an increase in heterosexual encounters after the age of 11. There appears to be a critical period between these ages in which heterosexual and kunyenga activities overlap. It is suggested that boys between these ages represent a potential bridge for HIV/AIDS infection between the general population and the relatively enclosed sexual network of street boys. [Tanzania, street children, HIV/AIDS, sexual behavior] [source] Green tea catechins as brain-permeable, natural iron chelators-antioxidants for the treatment of neurodegenerative disordersMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 2 2006Silvia Mandel Abstract Neurodegeneration in Parkinson's, Alzheimer's, or other neurodegenerative diseases appears to be multifactorial, where a complex set of toxic reactions, including oxidative stress (OS), inflammation, reduced expression of trophic factors, and accumulation of protein aggregates, lead to the demise of neurons. One of the prominent pathological features is the abnormal accumulation of iron on top of the dying neurons and in the surrounding microglia. The capacity of free iron to enhance and promote the generation of toxic reactive oxygen radicals has been discussed numerous times. The observations that iron induces aggregation of inert ,-synuclein and beta-amyloid peptides to toxic aggregates have reinforced the critical role of iron in OS-induced pathogenesis of neurodegeneration, supporting the notion that a combination of iron chelation and antioxidant therapy may be one significant approach for neuroprotection. Tea flavonoids (catechins) have been reported to possess divalent metal chelating, antioxidant, and anti-inflammatory activities, to penetrate the brain barrier and to protect neuronal death in a wide array of cellular and animal models of neurological diseases. This review aims to shed light on the multipharmacological neuroprotective activities of green tea catechins with special emphasis on their brain-permeable, nontoxic, transitional metal (iron and copper)-chelatable/radical scavenger properties. [source] Advances in the Pharmacological Treatment of Bipolar Affective DisordersPERSPECTIVES IN PSYCHIATRIC CARE, Issue 3 2003Susan McCabe EdD TOPIC Advances in the psychopharmacologic treatment of bipolar affective disorders (BPAD). PURPOSE To increase advanced practice nurses' ability to match prescribing practices with known etiological factors and the neurobiology of this complex set of disorders. SOURCES Published literature. CONCLUSIONS A wide array of pharmacological agents exist that can be useful to manage BPAD symptoms. APRNs play a critical role in helping patients and their families to use these drugs effectively. [source] Spin dynamics of exciton polaritons in microcavitiesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2005I. A. Shelykh Abstract In this chapter we address a complex set of optical phenomena linked to the spin dynamics of exciton polaritons in semiconductor microcavities. When optically created, polaritons inherit the spin and dipole moment from the exciting light. Their state can be fully characterized by a so-called "pseudospin" accounting for both spin and dipole moment orientation. However, from the very beginning of their life in a microcavity, polaritons start changing their pseudospin state under effect of effective magnetic fields of different nature and due to scattering with acoustic phonons, defects, and other polaritons. This makes pseudospin dynamics of exciton polaritons rich and complex. It manifests itself in non-trivial changes in polarization of light emitted by the cavity versus time, pumping energy, pumping intensity and polarization. During the first years of theoretical research on exciton-polariton relaxation the polarization has been simply neglected. Later it has been understood that the energy and momentum-relaxation of exciton polaritons are spin-dependent. It is typically the case in the regime of stimulated scattering when the spin polarizations of initial and final polariton state have a huge effect on the scattering rate between these states. It appeared that critical conditions for polariton Bose-condensation are also polarization-dependent. In particular, the stimulation threshold (i.e. the pumping power needed to have a population exceeding 1 at the ground state of the lower polariton branch) has been experimentally shown to be lower under linear than under circular pumping. These experimental observations have stimulated the theoretical research toward understanding of mutually dependent polarization- and energy-relaxation mechanisms in microcavities. The authors of this chapter have been working on theoretical description of different specific effects of polariton spin-dynamics in microcavities for years. Here we attempted to put together all fragments and to formulate a general approach to the problem that would allow then to consider a variety of particular cases. We start from reminding the main spin-relaxation mechanisms known for free carriers and excitons. We then overview the most essential experimental results in this field before to present our original formalism which allowed us to interpret the key experimental findings. We are going to discuss only the strong coupling regime leaving aside all polarization effects in VCSELs. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Neandertal cold adaptation: Physiological and energetic factorsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2002A. Theodore Steegmann Jr. European Neandertals employed a complex set of physiological cold defenses, homologous to those seen in contemporary humans and nonhuman primates. While Neandertal morphological patterns, such as foreshortened extremities and low relative surface-area, may have explained some of the variance in cold resistance, it is suggested the adaptive package was strongly dependent on a rich array of physiological defenses. A summary of the environmental cold conditions in which the Neandertals lived is presented, and a comparative ethnographic model from Tierra del Fuego is used. Muscle and subcutaneous fat are excellent "passive" insulators. Neandertals were quite muscular, but it is unlikely that they could maintain enough superficial body fat to offer much cold protection. A major, high-energy metabolic adaptation facilitated by modest amounts of highly thermogenic brown adipose tissue (BAT) is proposed. In addition, Neandertals would have been protected by general mammalian cold defenses based on systemic vasoconstriction and intensified by acclimatization, aerobic fitness, and localized cold-induced vasodilation. However, these defenses are energetically expensive. Based on contemporary data from circumpolar peoples, it is estimated that Neandertals required 3,360 to 4,480 kcal per day to support strenuous winter foraging and cold resistance costs. Several specific genetic cold adaptations are also proposed,heat shock protein (actually, stress shock protein), an ACP*1 locus somatic growth factor, and a specialized calcium metabolism not as yet understood. Am. J. Hum. Biol. 14:566,583, 2002. © 2002 Wiley-Liss, Inc. [source] Reproduction of an early-flowering Mediterranean mountain narrow endemic (Armeria caespitosa) in a contracting mountain islandPLANT BIOLOGY, Issue 4 2009R. García-Camacho Abstract Reproduction at population lower edges is important for plant species persistence, especially in populations on contracting high-mountain islands. In this context, the ability of plants to reproduce in different microhabitats seems to be important to guarantee seed production in stressful environments, such as Mediterranean high mountains. We hypothesised that the warmer and drier conditions at the lower edge would be deleterious for the reproduction of Armeria caespitosa, an early-flowering plant. In addition, reproductive plasticity along this mountain gradient may also be microhabitat-dependent. We studied factors affecting the reproductive success of A. caespitosa, an endemic of the Spanish Sistema Central. We considered a complex set of predictors, including phenology, plant size and environmental factors at different scales using generalised estimating equations and generalised linear models. Microhabitat, together with the position in the altitudinal gradient and inter-annual variability affected the reproduction of A. caespitosa. In addition, individuals with longer flowering periods (duration of flowering) had significantly lower fruit set and a higher number of unviable seeds; delayed flowering peaks favoured the production of both viable and unviable fruits. Microhabitat variability over an altitudinal range is relevant for the reproduction of A. caespitosa, and is more important at the lower edge of the altitudinal range, where the species faces the most adverse conditions. In addition, the ability to reproduce in different microhabitats might increase the chances of the species to cope with environmental uncertainties under on-going climate warming. Finally, reproduction of this early-flowering plant is constrained by summer drought, which might shape its reproductive phenology. [source] Effects of prior stimulus and prior perception on neural correlates of auditory stream segregationPSYCHOPHYSIOLOGY, Issue 6 2009Joel S. Snyder Abstract We examined whether effects of prior experience are mediated by distinct brain processes from those processing current stimulus features. We recorded event-related potentials (ERPs) during an auditory stream segregation task that presented an adaptation sequence with a small, intermediate, or large frequency separation between low and high tones (,f), followed by a test sequence with intermediate ,f. Perception of two streams during the test was facilitated by small prior ,f and by prior perception of two streams and was accompanied by more positive ERPs. The scalp topography of these perception-related changes in ERPs was different from that observed for ERP modulations due to increasing the current ,f. These results reveal complex interactions between stimulus-driven activity and temporal-context-based processes and suggest a complex set of brain areas involved in modulating perception based on current and previous experience. [source] Regime change and nation building: can donors restore governance in post-conflict states?PUBLIC ADMINISTRATION & DEVELOPMENT, Issue 1 2005Dennis A. Rondinelli Foreign aid agencies and international assistance organisations are now heavily involved in nation building in post-conflict states. Their record of strengthening democratic governance in countries where civil war or military force replaced unpopular regimes is mixed. Experience suggests that a complex set of conditions must be created quickly in order to rebuild indigenous governance. Ensuring security, providing assistance through a transparent and coherent plan of action, coordinating donors' activities, establishing strong and legitimate national authority, strengthening democratic political processes, transferring responsibility and resources for development to a new government, stabilising the economy and strengthening social capital and human assets must all be done in quick succession. Achieving these goals requires a cadre of civilian and, sometimes, military personnel with expertise in post-conflict nation building. The frequency with which government aid programmes and international assistance organisations engage in post-conflict reconstruction also suggests the need for more explicit national and international policies and the creation of specialised nation-building agencies to undertake these difficult tasks. Copyright © 2005 John Wiley & Sons, Ltd. [source] Regenerated synapses in lamprey spinal cord are sparse and small even after functional recovery from injuryTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 14 2010Paul A. Oliphint Abstract Despite the potential importance that synapse regeneration plays in restoring neuronal function after spinal cord injury (SCI), even the most basic questions about the morphology of regenerated synapses remain unanswered. Therefore, we set out to gain a better understanding of central synapse regeneration by examining the number, distribution, molecular composition, and ultrastructure of regenerated synapses under conditions in which behavioral recovery from SCI was robust. To do so, we used the giant reticulospinal (RS) neurons of lamprey spinal cord because they readily regenerate, are easily identifiable, and contain large synapses that serve as a classic model for vertebrate excitatory neurotransmission. Using a combination of light and electron microscopy, we found that regenerated giant RS synapses regained the basic structures and presynaptic organization observed at control giant RS synapses at a time when behavioral recovery was nearly complete. However, several obvious differences remained. Most strikingly, regenerated giant RS axons produced very few synapses. In addition, presynaptic sites within regenerated axons were less complex, had fewer vesicles, and had smaller active zones than normal. In contrast, the densities of presynapses and docked vesicles were nearly restored to control values. Thus, robust functional recovery from SCI can occur even when the structures of regenerated synapses are sparse and small, suggesting that functional recovery is due to a more complex set of compensatory changes throughout the spinal network. J. Comp. Neurol. 518:2854,2872, 2010. © 2010 Wiley-Liss, Inc. [source] Shifting Common Spaces of Plant Genetic Resources in the International Regulation of PropertyTHE JOURNAL OF WORLD INTELLECTUAL PROPERTY, Issue 3 2008Carolina Roa-Rodríguez The appellative "common heritage of mankind" is often used as a description of the property domain that governed plant genetic resources (PGR) at an international level up until the end of the twentieth century. However, the concept is rarely elaborated on. In this article we explore the origins of common property in PGR and the shifting content and shape of the genetic commons over the past several decades. Using the theoretical framework of diverse common property regimes developed by Peter Drahos, we chart the way in which the emergence and interaction of various international regulatory regimes related to PGR reshape common property spaces, rights and obligations. We argue that these international agreements do not regulate a single property domain in isolation, but rather modify the content and boundaries of the complex set of property domains that apply to PGR: private, state, common and public. More than a theoretical conundrum, we show that any realistic appraisal of the implementation of the international regulatory regimes in relation to PGR must acknowledge the conflicting and complex dynamics of these interrelated property domains, as well as the way in which they are being put into place on the ground. [source] A Quantitative Study of the Medial Surface Dynamics of an In Vivo Canine Vocal Fold during Phonation,THE LARYNGOSCOPE, Issue 9 2005Michael Doellinger PhD Abstract Objectives/Hypothesis: The purpose of this study was to measure the medial surface dynamics of a canine vocal fold during phonation. In particular, displacements, velocities, accelerations, and relative phase velocities of vocal fold fleshpoints were reported across the entire medial surface. Although the medial surface dynamics have a profound influence on voice production, such data are rare because of the inaccessibility of the vocal folds. Study Design: Medial surface dynamics were investigated during both normal and fry-like phonation as a function of innervation to the recurrent laryngeal nerve for conditions of constant glottal airflow. Methods: An in vivo canine model was used. The larynx was dissected similar to methods described in previous excised hemilarynx experiments. Phonation was induced with artificial airflow and innervation to the recurrent laryngeal nerve. The recordings were obtained using a high-speed digital imaging system. Three dimensional coordinates were computed for fleshpoints along the entire medial surface. The trajectories of the fleshpoints were preprocessed using the method of Empirical Eigenfunctions. Results: Although considerable variability existed within the data, in general, the medial-lateral displacements and vertical displacements of the vocal fold fleshpoints were large compared with anterior-posterior displacements. For both normal and fry-like phonation, the largest displacements and velocities were concentrated in the upper medial portion. During normal phonation, the mucosal wave propagated primarily in a vertical direction. Above a certain threshold of subglottal pressure (or stimulation to the recurrent laryngeal nerve), an abrupt transition from chest-like to fry-like phonation was observed. Conclusions: The study reports unique, quantitative data regarding the medial surface dynamics of an in vivo canine vocal fold during phonation, capturing both chest-like and fry-like vibration patterns. These data quantify a complex set of dynamics. The mathematical modeling of such complexity is still in its infancy and requires quantitative data of this nature for development, validation, and testing. [source] | |||||||||||||||||||||||||||||||||||||