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Differential Rates (differential + rate)
Selected AbstractsGrowth and Change in U.S. Cities and SuburbsGROWTH AND CHANGE, Issue 3 2001Robin M. Leichenko Differential rates of growth and decentralization are processes that characterized U.S. urban areas over the past three decades. This paper examines the determinants of growth in cities and suburbs during the 1970s, the 1980s, and the 1990s. The modeling approach adopted in the study allows for simultaneity between population and employment, and between cities and suburbs, while also taking into account a range of other explanatory factors. Results indicate that population and employment growth in cities tend to be jointly determined, but that growth of employment in the suburbs tends to drive growth of suburban population. Results also suggest that suburban and city growth are interrelated, but that the nature of these interrelationships varies over time: suburban growth promoted city growth during the 1970s and 1980s, while city and suburban growth were jointly determined during the 1990s. Other factors that consistently explain variation in city growth include demographics, population density, crime rates, and income inequality. Factors consistently explaining suburban growth include regional location and climate. [source] Differential rates of morphological divergence in birdsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2004F. Bokma Abstract There are more small-bodied bird species than there are large-bodied, even on a logarithmic scale. In birds this pattern, which is also found in other higher taxa, appears not to be due to neutral evolution. It has often been suggested that the skew of body size frequency distributions is the result of a relationship between body size and the net rate of speciation, but phylogenetic analyses so far have rejected the hypothesis that small-bodied species are subject to higher net rates of speciation. On the contrary, we show that there exists a relationship between body size and its own evolutionary variability: avian families of small body size show less interspecific variation in body size than large-bodied families of similar age and species richness. [source] Expression and regulation of alkaline phosphatases in human breast cancer MCF-7 cellsFEBS JOURNAL, Issue 5 2000Lai-Chen Tsai The effect of retinoic acid and dexamethasone on alkaline phosphatase (AP) expression was investigated in human breast cancer MCF-7 cells. Cellular AP activity was induced significantly by retinoic acid or dexamethasone in a time-dependent and dose-dependent fashion. A marked synergistic induction of AP activity was observed when the cells were incubated with both agents simultaneously. Two AP isozymes, tissue-nonspecific (TNAP) and intestinal (IAP), were shown to be expressed in MCF-7 cells as confirmed by the differential rate of thermal inactivation of these isozymes and RT-PCR. Based on the two-isozyme thermal-inactivation model, the specific activities for TNAP and IAP in each sample were analyzed. TNAP activity was induced only by retinoic acid and IAP activity was induced only by dexamethasone. Whereas dexamethasone conferred no significant effect on TNAP activity, retinoic acid was shown to inhibit IAP activity by , 50%. Interestingly, TNAP was found to be the only isozyme activity superinduced when the cells were costimulated with retinoic acid and dexamethasone. Northern blot and RT-PCR analysis were then used to demonstrate that the steady-state TNAP mRNA level was also superinduced, which indicates that the superinduction is regulated at the transcriptional or post-transcriptional levels. In the presence of the glucocorticoid receptor antagonist RU486, the dexamethasone-mediated induction of IAP activity was blocked completely as expected. However, the ability of RU486 to antagonize the action of glucocorticoid was greatly compromised in dexamethasone-mediated superinduction of TNAP activity. Furthermore, in the presence of retinoic acid, RU486 behaved as an agonist, and conferred superinduction of TNAP gene expression in the same way as dexamethasone. Taken together, these observations suggest that the induction of IAP activity by dexamethasone and the superinduction of TNAP by dexamethasone were mediated through distinct regulatory pathways. In addition, retinoic acid plays an essential role in the superinduction of TNAP gene expression by enabling dexamethasone to exert its agonist activity, which otherwise has no effect. [source] Findings Across Subgroups Regarding the Level of Response to Alcohol as a Risk Factor for Alcohol Use Disorders: A College Population of Women and LatinosALCOHOLISM, Issue 10 2004Marc A. Schuckit Background: The rates of alcohol dependence, a genetically influenced disorder, are increased among Latino men in the United States and are lower among women across ethnic groups. These analyses explored whether the differential rate of alcohol use disorders (AUDs) might reflect one genetically influenced phenotype related to alcoholism risk: the low level of response (LR) to alcohol. Methods: A questionnaire was mailed to students at two universities to identify drinking but not alcohol-dependent 18- to 29-year-old men and women who had a parent with alcohol dependence. Subjects were subsequently screened with a validated semistructured interview to corroborate the personal and family histories, and they participated in a challenge with alcohol 0.75 ml/kg for women and 0.90 ml/kg for men. LRs to alcohol were determined and compared between genders and between Latino versus Caucasian/Anglo subjects. Results: The data revealed no consistent significant differences between genders regarding either subjective feelings of intoxication or alcohol-induced changes in body sway. A similar lack of differential between groups was observed when Latino and Caucasian/Anglo subjects were compared. However, there was at least a statistical trend for interactions when gender, ethnicity, and time were considered together; there was some evidence for a higher LR in Latina women. Perhaps reflecting the different weights and doses of alcohol used, men demonstrated higher breath alcohol concentrations, but no differences in these values were noted between Latino and Anglo populations. Conclusions: The results indicate that the LR to alcohol is not likely to explain differences in rates of AUDs between genders or these two ethnic groups overall. The possibility that a higher LR might be seen for the subgroup with the lowest AUD rate,Latina women,will require replication in larger samples of well matched groups before definitive conclusions can be drawn. [source] Effect of Controlling Parameters on the Reaction Sequences of Formation of Nitrogen-Containing Magnesium Aluminate Spinel from MgO, Al2O3, and AlNJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2004Siddhartha Bandyopadhyay The reaction sequences of the formation of nitrogen-containing magnesium aluminate spinel from MgO, Al2O3, and AlN were investigated as a function of temperature through dilatometric study and as a function of time through isothermal heat treatments. The natures of reactions are described through the appearance of phases in conjunction with densification behavior and the change in lattice parameter of the spinel phase. Although the dilatometric study provides the detail insights of the formation sequence, the isothermal runs reveal new information about the differential rate of reactivity of the reacting species that suggested a tentative controlling mechanism. Through the initial formation of magnesium aluminate, oxygen-rich solid solution (MgAlON) forms, which ultimately reacts with the rest of AlN to reach its nominal composition. Nitrogen diffusion through MgAlON lattice seems to be rate controlling. [source] RACE, FRIENDSHIP NETWORKS, AND VIOLENT DELINQUENCYCRIMINOLOGY, Issue 4 2006DANA L. HAYNIE Although a growing body of literature emphasizes the role of friendship networks and peer relations for youth involvement in violence and delinquency, little research has examined the role of friendship networks in understanding the varying involvement of different racial-ethnic groups in violence. Using data from approximately 13,000 respondents to the first two waves of the National Longitudinal Study of Adolescent Health (Add Health), we explore the ability of friendship networks to account for the differential rates of violence among racial-ethnic groups. In addition, we evaluate whether race moderates the degree to which friendship characteristics predict adolescent violence. Findings indicate significant differences in the structure and behavioral orientation of friendship networks across racial-ethnic identities. Moreover, incorporating characteristics of friendship networks into multivariate analyses accounts for greater involvement in violence among black and Hispanic youths. Network racial heterogeneity and friends' popularity also emerge as particular network characteristics that operate differently for black and white youth. [source] The effects of selective breeding for differential rates of 50-kHz ultrasonic vocalizations on emotional behavior in ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2009Jeffrey Burgdorf Abstract Fifty-kHz ultrasonic vocalizations have previously been shown to be positively correlated with reward and appetitive social behavior in rats, and to reflect a positive affective state. In this study, rats selectively bred for high and low rates of 50-kHz vocalizations as juveniles were tested as adults in a battery of behavioral tests for social/emotional behaviors. We found that animals selectively bred for high rates of 50-kHz vocalizations exhibited more crosses into the center area of the open field apparatus, were more likely to show a preference for a dilute sucrose solution (.8%) compared to tap water, and were less aggressive than randomly bred animals. Conversely, animals bred for low rates of 50-kHz calls produced more fecal boli during both open field testing and "tickling" stimulation, and made less contact with conspecifics in a social interaction test compared to randomly bred animals. We also observed that low line rats have elevated brain levels of cholecystokinin (CCK) in the cortex, which is consistent with literature showing that CCK content in the cortex is positively correlated with rates of aversive 22-kHz USVs. Conversely, high line animals had elevated levels of met-enkephalin in several brain regions, which is consistent with the role of endogenous-opioids in the generation 50-kHz USVs and positive affect. These results suggest that animals bred for high rates of 50-kHz may show a stress resilient phenotype, whereas low line rats may show a stress prone phenotype. As such these animals could provide novel insights into the neurobiology of emotion. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 34,46, 2009 [source] Organic carbon additions: effects on soil bio-physical and physico-chemical propertiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2009A. Bhogal Summary The effects of organic carbon (OC) additions from farm manures and crop residues on selected soil bio-physical and physico-chemical properties were measured at seven experimental sites, on contrasting soil types, with a history of repeated applications of farm manure or differential rates of inorganic fertilizer nitrogen (N). Repeated (> 7 years annual additions) and relatively large OC inputs (up to 65 t OC ha,1) were needed to produce measurable changes in soil properties, particularly physical properties. However, over all the study sites, there was a positive relationship between OC inputs and changes in total soil OC and ,light' fraction OC (LFOC), with LFOC providing a more sensitive indicator of changes in soil organic matter status. Total soil OC increased by an average of 3% for every 10 t ha,1 manure OC applied, whereas LFOC increased by c. 14%. The measured soil OC increases were equivalent to c. 23% of the manure OC applied (up to 65 t OC ha,1 applied over 9 years) and c. 22% of the crop residue OC applied (up to 32 t OC ha,1 over 23 years). The manure OC inputs (but not crop residue OC inputs) increased topsoil porosity and plant available water capacity, and decreased bulk density by 0.6%, 2.5% and 0.5% with every 10 t ha,1 manure OC applied, respectively. Both OC sources increased the size of the microbial biomass (11% increase in biomass C with 10 t OC ha,1 input), but only manure OC increased its activity (16% increase in the soil respiration rate with 10 t OC ha,1 input). Likewise, the potentially mineralizable N pool only increased with manure N inputs (14% increase with 1 t manure total N ha,1). However, these soil quality benefits need to be balanced with any potential environmental impacts, such as excessive nutrient accumulation, increased nitrate leaching and phosphorus losses and gaseous emissions to the atmosphere. [source] The Diverging Geographies of Social and Business Interaction Patterns: a Case Study of Rural South AustraliaGEOGRAPHICAL RESEARCH, Issue 2 2000P.J. Smailes Major changes in personal mobility and in country town service provision have taken place in rural South Australia in the period 1968,69 to 1992,93. The later part of this period was one of major rural recession across Australia as a whole. The impact of this recession is considered by investigating changes in three different geographies of rural South Australians. These are their affective identification with place, their local social interaction and their commercial service consumption. There has been a shift of both commercial and social activity up through the hierarchy of settlement, but this is much more pronounced in the case of commercial activity. These differential rates of change are weakening the once mutually reinforcing links between community self-identification, social interaction and trading patterns. The full impact of the rural crisis commencing in 1982,83 on social and commercial spatial patterns is unlikely to have been achieved by 1992,93, and adjustment is likely to continue. [source] East,west: does it make a difference to hospital efficiencies in Ukraine?HEALTH ECONOMICS, Issue 11 2006Anatoly I. Pilyavsky Abstract Ukraine's history has given it a split personality (e.g. divergent cultural influences on economic and managerial behavior), as was observed in the recent political developments both prior to and following the December 2004 elections. Eastern regions were heavily influenced by Russo-Soviet rule, while western regions have more of a European outlook. This study, which is largely exploratory, compares recent trends in hospital efficiency in Ukraine to see if this split personality manifests itself in differential rates of improvement. Given the inflexibility of Soviet-style planned economies, it is hypothesized that western regions will show greater improvement in economic efficiency that can be attributed to higher levels of managerial and medical entrepreneurship. Data for this study comes from three oblasts (i.e. geopolitical regions), one in the west and two in the east, spanning from 1997 to 2001. Data envelopment analysis (DEA) was used to estimate technical efficiency for the hospitals. After correcting for bias, a second,stage Tobit regression was estimated. Results indicate that hospitals in the west improved efficiencies, while those in the east stayed constant. These western areas of the nation, being more amenable to western management and medical ,business' practice, may be quicker to pick up on new techniques to increase healthcare delivery efficiencies. This may stem from the more limited effects of a shorter history of incorporation into a Soviet-style planned and controlled economy in which individual decision-making and entrepreneurship was suppressed in favor of central decision-making by the state. Copyright © 2006 John Wiley & Sons, Ltd. [source] Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to streams in the southeastern United States using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks,HYDROLOGICAL PROCESSES, Issue 16 2009Anne B. Hoos Abstract Understanding how nitrogen transport across the landscape varies with landscape characteristics is important for developing sound nitrogen management policies. We used a spatially referenced regression analysis (SPARROW) to examine landscape characteristics influencing delivery of nitrogen from sources in a watershed to stream channels. Modelled landscape delivery ratio varies widely (by a factor of 4) among watersheds in the southeastern United States,higher in the western part (Tennessee, Alabama, and Mississippi) than in the eastern part, and the average value for the region is lower compared to other parts of the nation. When we model landscape delivery ratio as a continuous function of local-scale landscape characteristics, we estimate a spatial pattern that varies as a function of soil and climate characteristics but exhibits spatial structure in residuals (observed load minus predicted load). The spatial pattern of modelled landscape delivery ratio and the spatial pattern of residuals coincide spatially with Level III ecoregions and also with hydrologic landscape regions. Subsequent incorporation into the model of these frameworks as regional scale variables improves estimation of landscape delivery ratio, evidenced by reduced spatial bias in residuals, and suggests that cross-scale processes affect nitrogen attenuation on the landscape. The model-fitted coefficient values are logically consistent with the hypothesis that broad-scale classifications of hydrologic response help to explain differential rates of nitrogen attenuation, controlling for local-scale landscape characteristics. Negative model coefficients for hydrologic landscape regions where the primary flow path is shallow ground water suggest that a lower fraction of nitrogen mass will be delivered to streams; this relation is reversed for regions where the primary flow path is overland flow. Published in 2009 by John Wiley & Sons, Ltd. [source] Ecological biogeography of North American mammals: species density and ecological structure in relation to environmental gradientsJOURNAL OF BIOGEOGRAPHY, Issue 6 2000Catherine Badgley Abstract Aim, To evaluate the relationship of climate and physiography to species density and ecological diversity of North American mammals. Location, North America, including Mexico and Central America. Methods, Species density, size structure and trophic structure of mammalian faunas and nine environmental variables were documented for quadrats covering the entire continent. Spatial autocorrelation of species density and the environmental variables illustrated differences in their spatial structure at the continental scale. We used principal component analysis to reduce the dimensionality of the climatic variables, linear multiple regression to determine which environmental variables best predict species density for the continent and several regions of the continent, and canonical ordination to evaluate how well the environmental variables predict ecological structure of mammalian faunas over North America. Results, In the best regression model, five environmental variables, representing seasonal extremes of temperature, annual energy and moisture, and elevation, predicted 88% of the variation in species density for the whole continent. Among different regions of North America, the environmental variables that predicted species density vary. Changes in the size and trophic structure of mammalian faunas accompany changes in species density. Redundancy analysis demonstrated that environmental variables representing winter temperature, frostfree period, potential and actual evapotranspiration, and elevation account for 77% of the variation in ecological structure. Main conclusions, The latitudinal gradient in mammalian species density is strong, but most of it is explained by variation in the environmental variables. Each ecological category peaks in species richness under particular environmental conditions. The changes of greatest magnitude involve the smallest size categories (< 10 g, 11,100 g), aerial insectivores and frugivores. Species in these categories, mostly bats, increase along a gradient of decreasing winter temperature and increasing annual moisture and frostfree period, trends correlated with latitude. At the opposite end of this gradient, species in the largest size category (101,1000 kg) increase in frequency. Species in size categories 3 (101,1000 g), 5 (11,100 kg) and 6 (101,1000 kg), herbivores, and granivores increase along a longitudinal gradient of increasing annual potential evapotranspiration and elevation. Much of the spatial pattern is consistent with ecological sorting of species ranges along environmental gradients, but differential rates of speciation and extinction also may have shaped the ecological diversity of extant North American mammals. [source] A record of Late Pleistocene and Holocene carbon accumulation and climate change from an equatorial peat bog (Kalimantan, Indonesia): implications for past, present and future carbon dynamicsJOURNAL OF QUATERNARY SCIENCE, Issue 7 2004S. E. Page Abstract A 9.5,m core from an inland peatland in Kalimantan, Indonesia, reveals organic matter accumulation started around 26,000,cal.,yr,BP, providing the oldest reported initiation date for lowland ombrotrophic peat formation in SE Asia. The core shows clear evidence for differential rates of peat formation and carbon storage. A short period of initial accumulation is followed by a slow rate during the LGM, with fastest accumulation during the Holocene. Between ,13,000 and 8000,cal.,yr,BP, >,450,cm of peat were deposited, with highest rates of peat (>,2,mm,yr,1) and carbon (>,90,g,C,m,2,yr,1) accumulation between 9530 and 8590,cal.,yr,BP. These data suggest that Kalimantan peatlands acted as a large sink of atmospheric CO2 at this time. Slower rates of peat (0.15,0.38,mm,yr,1) and carbon (7.4,24.0,g,C,m,2,yr,1) accumulation between ,8000 and 500,cal.,yr,BP coincide with rapid peat formation in coastal locations elsewhere in SE Asia. The average LORCA (long-term apparent carbon accumulation rate) for the 9.5,m core is 56,g,C,m,2,yr,1. These data suggest that studies of global carbon sources, sinks and their dynamics need to include information on the past and present sizeable peat deposits of the tropics. Copyright © 2004 John Wiley & Sons, Ltd. [source] Bone marrow stem cells do not repopulate the healthy upper respiratory tract,PEDIATRIC PULMONOLOGY, Issue 4 2002Jane C. Davies MD Abstract Recent studies reported differentiation of both bone marrow and tissue-specific stem cells into cells of other organs. The demonstration that bone marrow stem cells differentiate into human hepatocytes in vivo has raised the possibility of new therapeutic approaches for liver disease. For diseases such as cystic fibrosis (CF), correction of the respiratory epithelium is being attempted by gene therapy. Differentiation of bone marrow stem cells into epithelium of the lung and airway was recently reported in an animal model, and would provide an alternative approach. We examined the nasal epithelium of female patients up to 15 years after gender-mismatched bone marrow transplantation. Donor-derived epithelial cells were sought with a combination of Y-chromosome fluorescence in situ hybridization and anti-cytokeratin antibody. In nasal brushing samples from 6 transplant-recipients, a median of 2.5% (range, 0.7,18.1%) of nuclei was male and identified as being of donor-origin. However, a complete absence of staining with anti-cytokeratin antibodies confirmed that these were not epithelial cells, but were likely to be either intraepithelial lymphocytes or mesenchymal cells. Following whole bone marrow transplantation, bone marrow progenitor cells do not differentiate into respiratory epithelium of the healthy upper airway. The differences between this and other studies could relate to the cells transplanted, to differential rates of turnover, or to the requirement for specific triggers to stimulate migration and differentiation. In the absence of such conditions, whole bone marrow transplantation is unlikely to provide a route for correction of the CF airway. Pediatr Pulmonol. 2002; 34:251,256. © 2002 Wiley-Liss, Inc. [source] Functional adaptation of the femoral head to voluntary exerciseTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2006Jeffrey H. Plochocki Abstract The functional adaptation of limb joints during postnatal ontogeny is necessary to maintain proper joint function. Joint form is modified primarily through differential rates of articular cartilage proliferation across articular surfaces during endochondral growth. This process is hypothesized to be mechanically regulated by the magnitude and orientation of stresses in the articular cartilage. However, the adaptation of limb joint morphology to the mechanical environment is poorly understood. We investigate the effects of voluntary exercise on femoral head morphology in 7-week-old female mice of the inbred strain C57BL/6J. The mice were divided into a control group and a group treated with voluntary access to an activity wheel for the duration of the 4-week study. Histomorphometric comparisons of chondral and osseous joint tissue of the proximal femur were made between control and exercise treatment groups. We find that exercised mice have significantly thicker articular cartilage with greater chondral tissue area and cellularity. Exercised mice also exhibit significantly greater bone tissue area and longer and flatter subchondral surfaces. No significant difference is found in the curvature of the articular cartilage or the length of the chondral articular surface between groups. These data suggest that a complex mechanistic relationship exists between joint stress and joint form. Joint tissue response to loading is multifaceted, involving both size and shape changes. Our data support the hypothesis that joint growth is ontogenetically plastic. Mechanical loading significantly influences chondral and subchondral tissue proliferation to provide greater support against increased mechanical loading. Anat Rec Part A, 288A:776,781, 2006 © 2006 Wiley-Liss, Inc. [source] Posttraumatic Symptoms, Functional Impairment, and Coping among Adolescents on Both Sides of the Israeli,Palestinian Conflict: A Cross-Cultural ApproachAPPLIED PSYCHOLOGY, Issue 4 2009Ruth Pat-Horenczyk This study assessed the effects of the ongoing violence on the mental health of Palestinian and Israeli youths. Parallel instruments were developed and adapted, as part of a collaborative project, in order to assess, in each society: (1) differential rates of exposure to the conflict, (2) the association between exposure and the severity of posttraumatic symptoms (PTS), and (3) the inter-relationships among PTS, functional impairment, somatic complaints, and coping strategies. Participants were 1,016 Israeli and 1,235 Palestinian adolescents. A self-report questionnaire assessed exposure. PTS was measured using the UCLA PTSD Reaction Index, functional impairment and somatic complaints were measured with the DISC, and coping strategies were assessed with Brief Cope. In both societies, greater exposure to conflict-related violence was associated with more PTS and more somatic complaints, with girls reporting more distress than boys. A total of 6.8 per cent of the Israeli students and 37.2 per cent of the Palestinian students met criteria for Post Traumatic Stress Disorder (PTSD). In both societies, but more pronounced in the Palestinian Authority, adolescents reported significant levels of functional impairment, mainly in the area of school functioning. Students with PTSD reported more somatic complaints as well as greater functional impairment. The results show the serious psychological impact of the ongoing violent conflict on Israeli and Palestinian students and point to the need to develop appropriate school-based interventions to address their mental health needs. Cette étude évalue les effets de la violence continuelle sur la santé mentale des jeunes palestiniens et israéliens. Des instruments analogues ont été développés et adaptés, dans le cadre d'un projet de collaboration, afin d'évaluer dans chaque société: (1) les différences de taux d'exposition au conflit, (2) l'association entre l'exposition et la sévérité des symptômes post-traumatiques (PTS) et (3) les interrelations entre les PTS, les troubles fonctionnels, les plaintes somatiques et les stratégies de faire-face. 1016 adolescents israéliens et 1235 adolescents palestiniens ont participéà cette étude. Un questionnaire auto-administré mesure l'exposition au conflit. Les PTS sont mesurés par l'utilisation de l'UCLA PTSD Reaction Index, les troubles fonctionnels et les plaintes somatiques sont approchés par le DISC, et les stratégies de faire-face par le Brief Cope. Dans les deux sociétés, une plus grande exposition au conflit et à ses violences est associée à des PTS plus importants et à plus de plaintes somatiques, les filles manifestant plus de détresse que les garçons. Un total de 6.8% des étudiants israéliens et 37.2% des étudiants palestiniens répondent à des critères du Post Traumatic Stress Disorder (PTSD). Dans les deux sociétés, mais de façon plus prononcée dans l'Autorité palestinienne, les adolescents rapportent des niveaux significatifs de troubles fonctionnels, principalement dans le domaine du fonctionnement scolaire. Les étudiants avec PTSD manifestent plus de plaintes somatiques, il en va de même pour les troubles fonctionnels. Les résultats montrent le sérieux impact psychologique d'un conflit violent et continuel sur les étudiants israéliens et palestiniens et signale le besoin de développer des interventions scolaires appropriées à leurs besoins en matière de santé mentale. [source] | ||||||||||||||||