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Important Questions (important + question)
Kinds of Important Questions Selected AbstractsLINEAGES WITH LONG DURATIONS ARE OLD AND MORPHOLOGICALLY AVERAGE: AN ANALYSIS USING MULTIPLE DATASETSEVOLUTION, Issue 4 2007Lee Hsiang Liow Lineage persistence is as central to biology as evolutionary change. Important questions regarding persistence include: why do some lineages outlive their relatives, neither becoming extinct nor evolving into separate lineages? Do these long-duration lineages have distinctive ecological or morphological traits that correlate with their geologic durations and potentially aid their survival? In this paper, I test the hypothesis that lineages (species and higher taxa) with longer geologic durations have morphologies that are more average than expected by chance alone. I evaluate this hypothesis for both individual lineages with longer durations and groups of lineages with longer durations, using more than 60 published datasets of animals with adequate fossil records. Analyses presented here show that groups of lineages with longer durations fall empirically into one of three theoretically possible scenarios, namely: (1) the morphology of groups of longer duration lineages is closer to the grand average of their inclusive group, that is, their relative morphological distance is smaller than expected by chance alone, when compared with rarified samples of their shorter duration relatives (a negative group morpho-duration distribution); (2) the relative morphological distance of groups of longer duration lineages is no different from rarified samples of their shorter duration relatives (a null group morpho-duration distribution); and (3) the relative morphological distance of groups of longer duration lineages is greater than expected when compared with rarified samples of their shorter duration relatives (a positive group morpho-duration distribution). Datasets exhibiting negative group morpho-duration distributions predominate. However, lineages with higher ranks in the Linnean hierarchy demonstrate positive morpho-duration distributions more frequently. The relative morphological distance of individual longer duration lineages is no different from that of rarified samples of their shorter duration relatives (a null individual morpho-duration distribution) for the majority of datasets studied. Contrary to the common idea that very persistent lineages are special or unique in some significant way, both the results from analyses of long-duration lineages as groups and individuals show that they are morphologically average. Persistent lineages often arise early in a group's history, even though there is no prior expectation for this tendency in datasets of extinct groups. The implications of these results for diversification histories and niche preemption are discussed. [source] Important questions in allergy: novel research areasALLERGY, Issue 2 2008J. Bousquet First page of article [source] Agricultural policies and the emergence of cotton as the dominant crop in northern Côte d'Ivoire: Historical overview and current outlookNATURAL RESOURCES FORUM, Issue 2 2009Oluyede Clifford Ajayi Abstract In most of sub-Saharan Africa, where the agricultural sector experiences dismal performance and is characterized by a gloomy picture, the cotton sub-sector in Côte d'Ivoire is often mentioned as a "success story" given the spectacular rise in the quantity of cotton production and the profile of the crop within the farming system. What are the historical and political antecedents of the development of cotton and the factors responsible for the feat accomplished in the midst of general failures in the same continent? To what extent can cotton be regarded as a "success story" and, what lessons can be drawn for agricultural development strategies based on the Ivorian case study? This paper traces the historical and socio-political background of cotton development in Côte d'Ivoire and identifies key policy and institutional interventions that have influenced the rise of cotton production and its emergence as the dominant crop in the farming systems of the country. Four stages in Ivorian cotton development are identified: planning, take off, crisis and the renaissance phases. The study demonstrates how a combination of good planning, technological advancement and appropriate policy and institutional conditions have contributed significantly to the rise of cotton production and its influence on the agricultural economy of northern Côte d'Ivoire. The study also highlights how the sustainability of agricultural development has been impacted by domestic and international policies and political events over which smallholder farm families have little control, and can at best only respond to. Important questions about cotton development in Côte d'Ivoire are raised that need to be answered before the program can be categorized conclusively as a success story. The study shows that there are no quick fixes to agricultural development in the sub-region. Rather, good planning and putting the necessary building blocks in place are important prerequisites. It is recommended that agricultural development efforts in the continent take cognizance of the complexity of the sector and address the inter-relationships that exist among the technical, policy, market and institutional factors that combine individually and collectively to influence African agriculture. [source] P-26 CONVENTIONAL V THIN LAYER TECHNIQUES: A COMPARATIVE STUDY OF BRONCHIAL SPECIMENS USING CONVENTIONAL AND TWO LBC METHODS, THINPREP AND SUREPATHCYTOPATHOLOGY, Issue 2006J. L. Conachan The current, conventional method used is quick, easy and reasonably cheap but the nature of bronchial specimens themselves creates the need for a better preparation technique. Bronchial specimens often present with many obscuring features, such as blood and mucus, which can affect definitive diagnosis. In the study, the bronchial specimens underwent routine conventional preparation and that remaining was used to prepare an LBC slide. Both LBC methods were separately evaluated alongside the conventional method where, of the 44 specimens used, half were prepared using the conventional and ThinPrep and half with the conventional and SurePath. Evaluation forms were completed by pathologists who assessed all preparations. The results showed both LBC methods produced superior preparations that were better fixed, more cellular and had improved nuclear detail. They also removed a high percentage of background debris, were more diagnostically accurate and reduced the inadequate rate by a third. The conventional slides prepared from the same specimen as the SurePath had a lower average than those prepared with the ThinPrep. This indicated that the specimens used to evaluate the SurePath method were in fact inferior to those used for ThinPrep, with the SurePath slides showing only a slight improvement in overall quality. Despite LBC preparations reducing pathologist screening and reporting time, both methods are more labour intensive and less cost effective. The majority of laboratories are not in the financial situation to trial new methods that require extra training and more staff hours, and as such this study has highlighted an important question ,Do the benefits of better quality preparation and diagnostic accuracy offset an increase in time and cost'. [source] The relationship of postprandial glucose to HbA1cDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue S2 2004Rüdiger Landgraf Abstract The gold standard for the assessment of the overall glycemic control is the determination of HbA1c. There are, however, insufficient data to determine reliably the relative contribution of fasting and postprandial plasma glucose to HbA1c. Increasing evidence suggests that excessive excursions of postprandial glucose might be important for the development of micro- and macroangiopathic complications. With respect to the treatment options, one important question to be answered is whether premeal, postmeal or fasting plasma glucose, alone or in combination, will be necessary in adjusting the therapy to achieve optimal HbA1c levels while minimizing hypoglycemia. HbA1c is difficult to predict from fasting plasma glucose. There are indications that there is a shift in the relative contribution from postprandial glucose at good to fair HbA1c levels (<7.3% to <9.2%) to fasting plasma glucose at high HbA1c (>9.3%). There is also a better correlation of afternoon and evening plasma glucose with HbA1c than with prebreakfast and prelunch plasma glucose values. Since the definition on how to define postprandial glucose is still a matter of debate and since postprandial glucose depends on the premeal blood glucose level and, on the time of the meal, its size and composition and the therapeutic strategy, the data so far available are inconclusive and the best correlation of HbA1c is with the area under the glucose profiles. Continuous glucose monitoring under daily life conditions will be the key to definitely unravel the relationship among HbA1c and fasting, premeal, postprandial and postabsorptive plasma glucose. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparative life-history traits in a fig wasp community: implications for community structureECOLOGICAL ENTOMOLOGY, Issue 2 2010MAHUA GHARA 1. Whether life-history traits can determine community composition and structure is an important question that has been well explored theoretically, but has received scant empirical attention. Life-history traits of a seven-member community of galler and parasitoid fig wasp species (Chalcidoidea), developing within the inflorescences (syconia) of Ficus racemosa (Moraceae) in India, were determined and used to examine community structure and ecology. 2. Gallers were pro-ovigenic (all eggs are mature upon adult emergence) whereas parasitoids were synovigenic (eggs mature progressively during adult lifespan). Initial egg load was correlated with body size for some species, and there was a trade-off between egg number and egg size across all species. Although all species completed their development and left the syconium concurrently, they differed in their adult and pre-adult lifespans. Providing sucrose solutions increased parasitoid lifespan but had no effect on the longevity of some galler species. While feeding regimes and body size affected longevity in most species, an interaction effect between these variables was detected for only one species. 3. Life-history traits of wasp species exhibited a continuum in relation to their arrival sequence at syconia for oviposition during syconium development, and therefore reflected their ecology. The largest number of eggs, smallest egg sizes, and shortest longevities were characteristic of the earliest-arriving galling wasps at the smallest, immature syconia; the converse characterised the later-arriving parasitoids at the larger, already parasitised syconia. Thus life history is an important correlate of community resource partitioning and can be used to understand community structure. 4. This is the first comprehensive study of life-history traits in a fig wasp community. The comparative approach revealed constraints and flexibility in trait evolution. [source] The need for adaptability in EU environmental policy design and implementationENVIRONMENTAL POLICY AND GOVERNANCE, Issue 5 2001Matthieu Glachant Is the application of the EU environmentally policy satisfying in the field? In particular, are the environmental objectives set in the directives met? This paper explores the issue of the effectiveness of the European environmental policy. It is based on the results of a recent study, which has consisted in evaluating the implementation of three pieces of EU environmental legislation in France, Germany, Netherlands and United Kingdom. The legislation studied was Directive 89/429 regulating atmospheric emissions from domestic waste incinerators, Directive 88/609 dealing with SO2 and NOx emissions from large combustion plants (LCPs) and Council Regulation 1836/93 concerning the voluntary participation of industrial companies in an EU Eco-Management and Audit Scheme (EMAS). The result of the study suggests that simply posing the problem in terms of ,implementation deficit' is not sufficient. In fact, over-compliance with directive goals is even observed in certain cases. By contrast, the evaluation suggests the prevalence of interactions between the considered implementation process and other parallel policy processes at the implementation stage. The study shows that this interplay between policies has a huge impact on implementation environmental results, which can be either positive or negative. Based on this statement, an important question for EU policy is how implementation can efficiently cope with such interactions, which means finding ways to maximize potential synergies, or alternatively to reduce inconsistencies, with the other policy components. Given that policy interactions are difficult to predict at the policy formulation stage of the policy, adjustments necessarily occur at the implementation stage. In this context, implementing EU environmental policy requires policy systems able to adjust at low costs. In this paper, this property is called adaptability and is given a precise content. Copyright © 2001 John Wiley & Sons, Ltd. and ERP Environment [source] Switching of the transmitters that mediate hindbrain correlated activity in the chick embryoEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2009Hiraku Mochida Abstract Widely propagating correlated neuronal activity is a hallmark of the developing nervous system. The activity is usually mediated by multiple transmitters, and the contribution of gap junctions has also been suggested in several systems. In some structures, such as the retina and spinal cord, it has been shown that the dominant transmitter mediating the correlated wave switches from acetylcholine to glutamate during development, although the functional significance of this phenomenon has not been clarified. An important question is whether such a transmitter switch occurs in other systems, especially in the brain. In the present study, we demonstrate that the major transmitter mediating correlated wave activity in the embryonic chick hindbrain changes from acetylcholine/,-aminobutyric acid (GABA)/glycine to glutamate/GABA as development proceeds. The results show for the first time that the dominant transmitter switches from acetylcholine to glutamate in a region other than the retina and spinal cord. This finding sheds more light on the role of nicotinic acetylcholine receptors in the generation of correlated wave activity, which is considered to regulate the development of the nervous system. [source] Centralizing Advisory Systems: Presidential Influence and the U.S. Foreign Policy Decision-Making ProcessFOREIGN POLICY ANALYSIS, Issue 2 2005David Mitchell This study is motivated by a simple yet vitally important question for an understanding of U.S. foreign policy. Quite simply, how does a president's choice of management style influence the U.S. foreign policy decision-making process and decision outcomes? Presidents play a critical role in the formulation of U.S. foreign policy; however, the presidential studies literature and foreign policy analysis literature arrive at very different conclusions regarding how presidents influence the policy process and both are often inaccurate. This study develops an Advisory Systems Typology to address how presidents influence the decision-making process. In addressing this question, this study overcomes the deficiencies of both the presidential studies and foreign policy analysis literature. Four different types of decision-making processes are produced by a president's choice of advisory structure and level of centralization. In addition, the study identifies "unstructured solutions" that indicate how the presidential advisers and president choose to resolve policy disagreements, thereby providing an indication of the decision outcome. The identified decision-making processes and their associated decision outcomes are explored using four cases of decision making on security policy drawn from the Nixon (Vietnam War), Carter (Strategic Arms Limitation Talks II), Reagan (Strategic Arms Reduction Talks I), and Clinton (Bosnia conflict) administrations. The case studies are constructed using the method of structured,focused comparisons, whereby a set of theoretically based questions and anticipated observations to those questions are made in order to guide the research and allow for comparison of decision making within and between cases. [source] A critical evaluation of genomic control methods for genetic association studiesGENETIC EPIDEMIOLOGY, Issue 4 2009Tony Dadd Abstract Population stratification is an important potential confounder of genetic case-control association studies. For replication studies, limited availability of samples may lead to imbalanced sampling from heterogeneous populations. Genomic control (GC) can be used to correct ,2 test statistics which are presumed to be inflated by a factor ,; this may be estimated by a summary ,2 value (,median or ,mean) from a set of unlinked markers. Many studies applying GC methods have used fewer than 50 unlinked markers and an important question is whether this can adequately correct for population stratification. We assess the behavior of GC methods in imbalanced case-control studies using simulation. SNPs are sampled from two subpopulations with intra-continental levels of FST (,0.005) and sampling schemata ranging from balanced to completely imbalanced between subpopulations. The sampling properties of ,median and ,mean are explored using 6,1,600 unlinked markers to estimate Type 1 error and power empirically. GC corrections based on the ,2 -distribution (GCmedian or GCmean) can be anti-conservative even when more than 100 single nucleotide polymorphisms (SNPs) are genotyped and realistic levels of population stratification exist. The GCF procedure performs well over a wider range of conditions, only becoming anti-conservative at low levels of , and with fewer than 25 SNPs genotyped. A substantial loss of power can arise when population stratification is present, but this is largely independent of the number of SNPs used. A literature survey shows that most studies applying GC have used GCmedian or GCmean, rather than GCF, which is the most appropriate GC correction method. Genet. Epidemiol. 2009. © 2008 Wiley Liss, Inc. [source] Seismic activity triggered by the 1999 Izmit earthquake and its implications for the assessment of future seismic riskGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2001Ali Pinar Summary A serious question has remained as to the location of the western end of the main rupture zone associated with the 1999 Izmit, Turkey, earthquake. A clear answer to this question is extremely important for the assessment of future seismic risk in the eastern Marmara Sea region, Turkey. In this paper we show an effective approach to answering this important question, unifying different kinds of information such as seismic activity, focal mechanism solutions and stress changes caused by the main shock into a clear image. We first point out that the major moment release is 1.6 × 1020 N m and covered the area between 29.7°E and 30.5°E and we then claim that the enhanced seismic activity after the main shock in the eastern Marmara Sea region should be regarded as activity triggered by the increase of stress, rather than as aftershock activity along the ruptured zone. We propose three fault segments with an average stress increase on each in the western extension of the main-shock rupture zone as potential sites for future large earthquakes, namely (i) the 50 km long Yalova,Hersek segment (0.45 MPa), (ii) the NW,SE-trending right-lateral strike-slip fault known as the Princes Islands segment (0.18 MPa), and (iii) the Çinarcik,Yalova segment (0.09 MPa) characterized by normal faulting, which was subject to rupture in 1963. [source] Deterministic and Stochastic Modeling of Aquifer Stratigraphy, South CarolinaGROUND WATER, Issue 2 2000Russell B. Miller Deterministic and stochastic methods of three-dimensional hydrogeologic modeling are applied to characterization of contaminated Eocene aquifers at the Savannah River Site, South Carolina. The results address several important issues, including the use of multiple types of data in creating high-resolution aquifer models and the application of sequence-stratigraphic constraints. Specific procedures used include defining grid architecture stratigraphically, upscaling, modeling lithologic properties, and creating multiple equiprobable realizations of aquifer stratigraphy. An important question answered by the study is how to incorporate gamma-ray borehole-geophysical data in areas of anomalous log response, which occurs commonly in aquifers and confining units of the Atlantic Coastal Plain and other areas. To overcome this problem, gamma-ray models were conditioned to grain-size and lithofacies realizations. The investigation contributes to identifying potential pathways for downward migration of contaminants, which have been detected in confined aquifers at the modeling site. The approach followed in this investigation produces quantitative, stratigraphically constrained, geocellular models that incorporate multiple types of data from borehole-geophysical logs and continuous cores. The use of core-based stochastic realizations in conditioning deterministic models provides the advantage of incorporating lithologic information based on direct observations of cores rather than using only indirect measurements from geophysical logs. The high resolution of the models is demonstrated by the representation of thin, discontinuous clay beds that act as local barriers to flow. The models are effective in depicting the contrasts in geometry and heterogeneity between sheet-like nearshore-transgressive sands and laterally discontinuous sands of complex shoreline environments. [source] Keeping nurses at work: a duration analysisHEALTH ECONOMICS, Issue 6 2002Tor Helge HolmåsArticle first published online: 9 AUG 200 Abstract A shortage of nurses is currently a problem in several countries, and an important question is therefore how one can increase the supply of nursing labour. In this paper, we focus on the issue of nurses leaving the public health sector by utilising a unique data set containing information on both the supply and demand side of the market. To describe the exit rate from the health sector we apply a semi-parametric hazard rate model. In the estimations, we correct for unobserved heterogeneity by both a parametric (Gamma) and a non-parametric approach. We find that both wages and working conditions have an impact on nurses' decision to quit. Furthermore, failing to correct for the fact that nurses' income partly consists of compensation for inconvenient working hours results in a considerable downward bias of the wage effect. Copyright © 2002 John Wiley & Sons, Ltd. [source] Role of the Charge Transfer State in Organic Donor,Acceptor Solar CellsADVANCED MATERIALS, Issue 37 2010Carsten Deibel Charge transfer complexes are interfacial charge pairs residing at the donor,acceptor heterointerface in organic solar cell. Experimental evidence shows that it is crucial for the photovoltaic performance, as both photocurrent and open circuit voltage directly depend on it. For charge photogeneration, charge transfer complexes represent the intermediate but essential step between exciton dissotiation and charge extraction. Recombination of free charges to the ground state is via the bound charge transfer state before being lost to the ground state. In terms of the open circuit voltage, its maximum achievable value is determined by the energy of the charge transfer state. An important question is whether or not maximum photocurrent and maximum open circuit voltage can be achieved simultaneously. The impact of increasing the CT energy,in order to raise the open circuit voltage, but lowering the kinetic excess energy of the CT complexes at the same time,on the charge photogeneration will accordingly be discussed. Clearly, the fundamental understanding of the processes involving the charge transfer state is essential for an optimisation of the performance of organic solar cells. [source] Searching for Sacajawea: Whitened Reproductions and Endarkened RepresentationsHYPATIA, Issue 2 2007Wanda Pillow Pillow's aim is to demonstrate how representations of Sacajawea have shifted in writings about the Lewis and Clark expedition in ways that support manifest destiny and white colonial projects. This essay begins with a general account of Sacajawea. The next section uses two novels (one hundred years apart) to make the case that shifts in the representation of this important historical figure serve similar purposes. There is some attention to white suffragist representations, but the central contrast is between manifest destiny and multiculturalism. The final section addresses the important question of whether it is possible for feminists to theorize Sacajawea in ways that are not co-opted by colonial projects. [source] Urban mesh and ad hoc mesh networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2008Anders Nilsson Plymoth Mesh networking is currently gaining much attention, within both academia and industry. Mesh networking allows cheap and fast deployment of wireless services. It is regarded as a very promising solution for urban deployment scenarios as well as for temporary emergency response situations. Another related promising field is that of ad hoc wireless networking, which consists of mobile nodes that dynamically create and maintain a network without the need for any infrastructure. We propose a solution and architecture for urban mesh ad hoc networks, a network that combines mesh networking with ad hoc networks for urban environments. We present four types of ad hoc mesh and ad hoc mesh networks. The most general one consists of mesh nodes, called mesh points (MP), that act as a type of access point for user nodes (UN). The MPs have at least two interfaces: one which is used to communicate with UNs, and one which is used to maintain the mesh access network and transport data. These two interfaces can basically use any type of technology (IEEE 802.11 a/b/g, WiMax, etc.), and for capacity reasons it is generally regarded that the best solution is to let the mesh interface operate on a separate high-capacity channel or channels. An intricate part of these types of networks are routing and location services. In our solution, UN devices operate in ad hoc mode running an ad hoc routing protocol. This allows UNs that wish to communicate to connect directly in an ad hoc manner, or through an MP. An important question is therefore whether two UNs that wish to communicate should connect through the mesh or connect directly. We show that from a capacity point of view whether a UN should route its packets to the closest available MP, or through a ad hoc network, depends on the environment the network is located, the amount traffic and the type of protocols used. Since MPs need to know where to route packets within the mesh, i.e., locating the MP closest to the destination UN, each UN run a small application that registers the UN to the mesh network. In addition to the above features we have developed a new MAC that quickly queries two candidate nodes, which picks the candidate with the currently best radio conditions. This enable nodes to cope with deep dips in signal strength due to fast fading, a well-known problem in urban environments. We show that this new protocol achieves significantly lower delays. We also show that in dense urban environments performance and battery lifetime can be improved if ad hoc technologies are used. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of Service Structure and Organization on Staff Care Practices in Small Community Homes for People with Intellectual DisabilitiesJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 5 2008Jim Mansell Background, An important question in community living is what factors influence the extent to which staff provide ,active support'. Methods, Engagement, care practices and a range of staff and organizational characteristics were studied in 72 residential homes serving 359 adults with intellectual disabilities. Managers in 36 settings were trained in person-centred active support (PCAS). A group comparison design and multivariate analysis was used to investigate the relationship between variables. Results, The PCAS group showed more active support, assistance, other contact from staff and engagement in meaningful activity but no difference in choice-making or assessment of participation in activities of daily living. The PCAS group had more staff with a professional qualification, were more likely to think that challenging behaviour was caused by lack of stimulation, had attitudes more in line with a policy of community care, rated most care tasks as less difficult, and were more organized to deliver active support. The comparison group were more likely to think that challenging behaviour was learned negative behaviour, showed more teamwork and were more satisfied. Multivariate analysis identified a range of staff and organizational variables associated with engagement and active support. Conclusions, The results suggest that some variables which have not hitherto been studied in relation with active support are associated with it. Professional qualification, knowledge and experience appear to be important as do some staff attitudes, clear management guidance, more frequent supervision and team meetings, training and support for staff to help residents engage in meaningful activity. [source] Origin matters: Differences in embryonic tissue origin and Wnt signaling determine the osteogenic potential and healing capacity of frontal and parietal calvarial bonesJOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2010Natalina Quarto Abstract Calvarial bones arise from two embryonic tissues, namely, the neural crest and the mesoderm. In this study we have addressed the important question of whether disparate embryonic tissue origins impart variable osteogenic potential and regenerative capacity to calvarial bones, as well as what the underlying molecular mechanism(s). Thus, by performing in vitro and in vivo studies, we have investigated whether differences exist between neural crest,derived frontal and paraxial mesodermal,derived parietal bone. Of interest, our data indicate that calvarial bone osteoblasts of neural crest origin have superior potential for osteogenic differentiation. Furthermore, neural crest,derived frontal bone displays a superior capacity to undergo osseous healing compared with calvarial bone of paraxial mesoderm origin. Our study identified both in vitro and in vivo enhanced endogenous canonical Wnt signaling in frontal bone compared with parietal bone. In addition, we demonstrate that constitutive activation of canonical Wnt signaling in paraxial mesodermal,derived parietal osteoblasts mimics the osteogenic potential of frontal osteoblasts, whereas knockdown of canonical Wnt signaling dramatically impairs the greater osteogenic potential of neural crest,derived frontal osteoblasts. Moreover, fibroblast growth factor 2 (FGF-2) treatment induces phosphorylation of GSK-3, and increases the nuclear levels of ,-catenin in osteoblasts, suggesting that enhanced activation of Wnt signaling might be mediated by FGF. Taken together, our data provide compelling evidence that indeed embryonic tissue origin makes a difference and that active canonical Wnt signaling plays a major role in contributing to the superior intrinsic osteogenic potential and tissue regeneration observed in neural crest,derived frontal bone. © 2010 American Society for Bone and Mineral Research [source] Clonal analysis of cutaneous fibrous histiocytoma (dermatofibroma)JOURNAL OF CUTANEOUS PATHOLOGY, Issue 7 2002Pei Hui Background:, Dermatofibroma (DF) or cutaneous fibrous histiocytoma is a common benign fibrohistiocytic lesion involving the dermis and subcutis. Histologically, it is subclassified into fibroblastic and histiocytoid forms. Its histogenesis is controversial. While often referred to as a neoplastic process, definite evidence of neoplasia in DF has been lacking. Alternatively, some authorities have suggested that DF is a fibrosing inflammatory process. Diagnostically, the most important question faced is the distinction from dermatofibrosarcoma protuberans (DFSP). Misdiagnosis can occur, as the early phase of DFSP can simulate DF, particularly the deep and cellular forms of DF. Methods:, To address this issue, and to investigate whether DF is in fact a neoplasm, we evaluated 31 examples of DF of various histological types in female patients and assessed clonality by analyzing X-chromosome inactivation as indicated by the methylation status of the androgen receptor gene (HUMARA). Representative cases of DFSP were analyzed for comparison. Results:, Among the selected 31 cases of DF, 24 cases provided intact DNA and informative polymorphism at the AR alleles, including one case of recurrent deep fibrous histiocytoma. Among these 24 cases, randomly inactivated AR alleles were observed in 17 cases including a deep, recurrent fibroblastic DF. A non-random inactivation at AR alleles was observed in seven cases, of which six cases showed either typical histiocytoid form of DF (four cases) or mixed cell types with predominant histiocytoid cell type (two cases). One fibroblastic DF also showed a monoclonal pattern. HUMARA analysis of DFSP revealed non-random inactivation of polymorphic AR alleles. Conclusions:, These findings suggest that DF is a heterogeneous process. Monoclonal genotype was found in DFs with histiocytoid or mixed type with predominant histiocytoid features, suggesting that histiocytoid cells probably represent the neoplastic component. The fibroblastic form of DF may represent a reactive fibroblastic proliferation. Alternatively, it may represent a true neoplasm whose neoplastic cell type has been obscured by prominent reactive fibroblastic component. [source] Are mice calorically restricted in nature?AGING CELL, Issue 4 2003Steven N. Austad Summary An important question about traditional caloric restriction (CR) experiments on laboratory mice is how food intake in the laboratory compares with that of wild mice in nature. Such knowledge would allow us to distinguish between two opposing views of the anti-aging effect of CR , whether CR represents, in laboratory animals, a return to a more normal level of food intake, compared with excess food consumption typical of laboratory conditions or whether CR represents restriction below that of animals living in nature, i.e. the conditions under which house mice evolved. To address this issue, we compared energy use of three mouse genotypes: (1) laboratory-selected mouse strains (= laboratory mice), (2) house mice that were four generations or fewer removed from the wild (= wild-derived mice) and (3) mice living in nature (= wild mice). We found, after correcting for body mass, that ad libitum fed laboratory mice eat no more than wild mice. In fact, under demanding natural conditions, wild mice eat even more than ad libitum fed laboratory mice. Laboratory mice do, however, eat more than wild-derived mice housed in similar captive conditions. Therefore, laboratory mice have been selected during the course of domestication for increased food intake compared with captive wild mice, but they are not particularly gluttonous compared with wild mice in nature. We conclude that CR experiments do in fact restrict energy consumption beyond that typically experienced by mice in nature. Therefore, the retarded aging observed with CR is not due to eliminating the detrimental effects of overeating. [source] MicroRNAs: Master Regulators of Ethanol Abuse and Toxicity?ALCOHOLISM, Issue 4 2010Rajesh C. Miranda Ethanol exerts complex effects on human physiology and health. Ethanol is not only addictive, but it is also a fetal teratogen, an adult neurotoxin, and an etiologic agent in hepatic and cardiovascular disease, inflammation, bone loss, and fracture susceptibility. A large number of genes and signaling mechanisms have been implicated in ethanol's deleterious effects leading to the suggestion that ethanol is a "dirty drug." An important question is, are there cellular "master-switches" that can explain these pleiotropic effects of ethanol? MicroRNAs (miRNAs) have been recently identified as master regulators of the cellular transcriptome and proteome. miRNAs play an increasingly appreciated and crucial role in shaping the differentiation and function of tissues and organs in both health and disease. This critical review discusses new evidence showing that ethanol-sensitive miRNAs are indeed regulatory master-switches. More specifically, miRNAs control the development of tolerance, a crucial component of ethanol addiction. Other drugs of abuse also target some ethanol-sensitive miRNAs suggesting that common biochemical mechanisms underlie addiction. This review also discusses evidence that miRNAs mediate several ethanol pathologies, including disruption of neural stem cell proliferation and differentiation in the exposed fetus, gut leakiness that contributes to endotoxemia and alcoholic liver disease, and possibly also hepatocellular carcinomas and other gastrointestinal cancers. Finally, this review provides a perspective on emerging investigations into potential roles of miRNAs as mediators of ethanol's effects on inflammation and fracture healing, as well as the potential for miRNAs as diagnostic biomarkers and as targets for therapeutic interventions for alcohol-related disorders. [source] Globalisation and science education: Rethinking science education reformsJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 5 2005Lyn Carter Like Lemke (J Res Sci Teach 38:296,316, 2001), I believe that science education has not looked enough at the impact of the changing theoretical and global landscape by which it is produced and shaped. Lemke makes a sound argument for science education to look beyond its own discourses toward those like cultural studies and politics, and to which I would add globalisation theory and relevant educational studies. Hence, in this study I draw together a range of investigations to argue that globalisation is indeed implicated in the discourses of science education, even if it remains underacknowledged and undertheorized. Establishing this relationship is important because it provides different frames of reference from which to investigate many of science education's current concerns, including those new forces that now have a direct impact on science classrooms. For example, one important question to investigate is the degree to which current science education improvement discourses are the consequences of quality research into science teaching and learning, or represent national and local responses to global economic restructuring and the imperatives of the supranational institutions that are largely beyond the control of science education. Developing globalisation as a theoretical construct to help formulate new questions and methods to examine these questions can provide science education with opportunities to expand the conceptual and analytical frameworks of much of its present and future scholarship. © 2005 Wiley-Liss, Inc. [source] Comparing bibliometric statistics obtained from the Web of Science and ScopusJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2009Éric Archambault For more than 40 years, the Institute for Scientific Information (ISI, now part of Thomson Reuters) produced the only available bibliographic databases from which bibliometricians could compile large-scale bibliometric indicators. ISI's citation indexes, now regrouped under the Web of Science (WoS), were the major sources of bibliometric data until 2004, when Scopus was launched by the publisher Reed Elsevier. For those who perform bibliometric analyses and comparisons of countries or institutions, the existence of these two major databases raises the important question of the comparability and stability of statistics obtained from different data sources. This paper uses macrolevel bibliometric indicators to compare results obtained from the WoS and Scopus. It shows that the correlations between the measures obtained with both databases for the number of papers and the number of citations received by countries, as well as for their ranks, are extremely high (R2 , .99). There is also a very high correlation when countries' papers are broken down by field. The paper thus provides evidence that indicators of scientific production and citations at the country level are stable and largely independent of the database. [source] What are teenagers reading?LITERACY, Issue 3 2005Adolescent fiction reading habits, reading choices Abstract What are adolescents choosing to read? This is an important question because of potential divergence between school students' reading interests and reading expectations in school. This article considers the findings from a study of the reading over one week in May 2002 of 707 school students aged between 11 and 15, undertaken in 30 schools in the south-west of England. The findings are related to earlier research by, amongst others, Whitehead, Benton, and Hall and Coles. The article reflects on adolescent reading choices, influences on those choices and the importance of validating all reading experience, including the new literacies. [source] GROWTH, COMMODITY PRICES, INFLATION AND THE DISTRIBUTION OF INCOMEMETROECONOMICA, Issue 1 2007Harry Bloch ABSTRACT A primary commodity price boom is underway. Given the role of internationally traded primary commodities as inputs into the productive process in the industrialized world, an important question arises: namely what effects will this price-boom exert upon wage and price inflation in industrialized countries? In order to address this question, we specify and estimate a system of equations in which the key dependent variables are world commodity prices, the domestic inflation rate for finished goods and the rate of domestic industrial wage inflation. This model is estimated against data for each of three major industrialized countries: Japan, the UK and the USA and the implications of the results thus obtained are explored. [source] Land clearing reduces gene flow in the granite outcrop-dwelling lizard, Ctenophorus ornatusMOLECULAR ECOLOGY, Issue 19 2010ESTHER LEVY Abstract An important question for the conservation of species dwelling in fragmented habitats is whether changes to the intervening landscape create a barrier to gene flow. Here, we make use of the spatial distribution of the granite outcrop-dwelling lizard, Ctenophorus ornatus, to compare inferred levels of gene flow between outcrops in a nature reserve with that between outcrops in the adjacent agricultural land. Genetic variation, relatedness and subdivision were compared within groups of individuals from different outcrops similar in size and distance apart at each site. In the agricultural land, we found significantly lower genetic variation within outcrops and greater genetic differentiation between outcrops than in the reserve. Further, the rate at which genetic divergence between outcrops increased over geographical distance was significantly greater in the agricultural land than in the reserve. We also found that individuals were more closely related within outcrops but more distantly related between outcrops in the cleared land. These effects occur over a small spatial scale with an average distance between outcrops of less than five kilometres. Thus, even though land clearing around the outcrops leaves outcrop size unchanged, it restricts gene flow, reducing genetic variation and increasing population structure, with potentially negative consequences for the long-term persistence of the lizards on these outcrops. [source] The linkage disequilibrium between chloroplast DNA and mitochondrial DNA haplotypes in Beta vulgaris ssp. maritima (L.): the usefulness of both genomes for population genetic studiesMOLECULAR ECOLOGY, Issue 2 2000B. Desplanque Abstract The structure and evolution of the plant mitochondrial genome may allow recurrent appearance of the same mitochondrial variants in different populations. Whether the same mitochondrial variant is distributed by migration or appears recurrently by mutation (creating homoplasy) in different populations is an important question with regard to the use of these markers for population genetic analyses. The genetic association observed between chloroplasts and mitochondria (i.e. two maternally inherited cytoplasmic genomes) may indicate whether or not homoplasy occurs in the mitochondrial genome. Four-hundred and fourteen individuals sampled in wild populations of beets from France and Spain were screened for their mitochondrial and chloroplast polymorphisms. Mitochondrial DNA (mtDNA) polymorphism was investigated with restriction fragment length polymorphism (RFLP) and chloroplast DNA (cpDNA) polymorphism was investigated with polymerase chain reaction PCR,RFLP, using universal primers for the amplification. Twenty and 13 variants for mtDNA and cpDNA were observed, respectively. Most exhibited a widespread geographical distribution. As a very strong linkage disequilibrium was estimated between mtDNA and cpDNA haplotypes, a high rate of recurrent mutation was excluded for the mitochondrial genome of beets. Identical mitochondrial variants found in populations of different regions probably occurred as a result of migration. We concluded from this study that mtDNA is a tool as valuable as cpDNA when a maternal marker is needed for population genetics analyses in beet on a large regional scale. [source] Structural mechanisms of multidrug recognition and regulation by bacterial multidrug transcription factorsMOLECULAR MICROBIOLOGY, Issue 4 2002Maria A. Schumacher Summary The increase in bacterial resistance to multiple drugs represents a serious and growing health risk. One component of multidrug resistance (MDR) is a group of multidrug transporters that are often regulated at the transcriptional level by repressors and/or activators. Some of these transcription factors are also multidrug-binding proteins, frequently recognizing the same array of drugs that are effluxed by the transporters that they regulate. How a single protein can recognize such chemically disparate compounds is an intriguing question from a structural standpoint and an important question in future drug development endeavours. Unlike the multidrug transporters, the cytosolic multidrug-binding regulatory proteins are more tractable systems for structural analyses. Here, we describe recent crystallographic studies on MarR, BmrR and QacR, three bacterial transcription regulators that are also multidrug-binding proteins. Although our understanding of multidrug binding and transcriptional regulation by MarR is in its initial stages, the structure of a BmrR,TPP+,DNA complex has revealed important insights into the novel transcription activation mechanism of the MerR family, and the structures of a QacR,DNA complex and QacR bound to six different drugs have revealed not only the mechanism of induction of this repressor but has afforded the first view of any MDR protein bound to multiple drugs. [source] Catch-up Growth or Regression to the Mean?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2005Recovery from Stunting Revisited An important question for policy is the extent to which catch-up growth can ease the impact of early stunting. Martorell et al. (1992) showed that stunted Guatemalan infants remain stunted into adulthood, whereas Adair (1999) found appreciable catch-up growth in Filipino children from 2,12 years. Both groups defined catch-up as an inverse correlation between early height and subsequent growth, but Martorell based the correlation on height, whereas Adair used height z scores. The statistical phenomenon of regression to the mean is much like catch-up growth, an inverse correlation between initial height and later height gain. The objective of this study was to reexamine the relationship between stunting and later catch-up growth in the context of regression to the mean. The design was a theoretical analysis showing that catch-up growth is more evident based on height z scores than on height, validated using data on 495 stunted South African children seen at 2 and 5 years of age. The correlation between height at 2 and height change from 2 to 5 was small based on height (,0.11) but large and highly significant based on height z score (,0.58), providing strong evidence of catch-up growth. We argue that catch-up growth should be estimated using height z score not height and that catch-up is present only when the change in z score exceeds that predicted by regression to the mean. This leads to a compact definition of catch-up growth: if z1 and z2 are the initial and final (mean) height z scores, and r is the correlation between them, then catch-up growth for groups or individuals is given by (z2 , rz1). Am. J. Hum. Biol. 17:412,417, 2005. © 2005 Wiley-Liss, Inc. [source] Motor imagery after stroke: Relating outcome to motor network connectivity,ANNALS OF NEUROLOGY, Issue 5 2009Nikhil Sharma PhD Objective Neuroplasticity is essential for recovery after stroke and is the target for new stroke therapies. During recovery from subcortical motor stroke, brain activations associated with movement may appear normal despite residual functional impairment. This raises an important question: how far does recovery of motor performance depend on the processes that precede movement execution involving the premotor and prefrontal cortex, rather than recovery of the corticospinal system alone? Methods We examined stroke patients with functional magnetic resonance imaging while they either imagined or executed a finger-thumb opposition sequence. In addition to classical analyses of regional activations, we studied neuroplasticity in terms of differential network connectivity using structural equation modeling. The study included 8 right-handed patients who had suffered a left-hemisphere subcortical ischemic stroke with paresis, and 13 age-matched healthy controls. Results With good functional recovery, the regional activations had returned to normal in patients. However, connectivity within the extended motor network remained abnormal. These abnormalities were seen predominantly during motor imagery and correlated with motor performance. Interpretation Our results indicate that neuroplasticity can manifest itself as differences in connectivity among cortical areas remote from the infarct, rather than in the degree of regional activation. Connection strengths between nodes of the cortical motor network correlate with motor outcome. The altered organization of connectivity of the prefrontal areas may reflect the role of the prefrontal cortex in higher order planning of movement. Our results are relevant to the assessment and understanding of emerging physical and neurophysiological therapies for stroke rehabilitation. Ann Neurol 2009;66:604,616 [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||