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Big Challenge (big + challenge)
Selected AbstractsBig-Leaf Mahogany on CITES Appendix II: Big Challenge, Big OpportunityCONSERVATION BIOLOGY, Issue 3 2005JAMES GROGAN First page of article [source] Small Samples, Big Challenges: Studying Atypical Family FormsJOURNAL OF MARRIAGE AND FAMILY, Issue 4 2005Simon Cheng We discuss the challenges of small-subsample sizes that family scholars often encounter when studying nontraditional or less common family types. We begin by identifying the general difficulties of using existing data in this line of research and then discuss potential solutions that may help researchers to avoid these problems. Using data from the Early Childhood Longitudinal Study, we use the example of monoracial White, monoracial Asian, and Asian/White interracial families to illustrate these problems and available, albeit imperfect, solutions. [source] ESCI award lecture: from a little mouse to rationale medicine for bone lossEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 10 2009A. Leibbrandt Abstract Completion of the human genome is one of the many significant milestones in the new era of systems biology. The current phase of genomic studies is focused upon parsing this new found genetic data with respect to scientific interest, and economic and health impact applications. As the sequences are now available and whole genome single nucleotide polymorphism maps for multiple human diseases will be available with the advent of modern genomics, the big challenge is to determine the function of these genes in the context of the entire organism. The emphasis is therefore on functional genomic analysis that represents the new front-line and limiting factor for realizing potential benefits of genome-based science. Defined gene targeting has been proven to be particularly useful as loss of expression mutants can reveal essential functions of molecules and the pathogenesis of disease. Using gene-targeted mice, my group has over the years identified genes that control heart and lung functions [1,5]; apoptosis [6,9]; lymphocyte activation [10,14]; cancer [15,17]; pain [18]; diabetes [19]; fertility [20] or wound healing [21]. In this study, I would like to review our work on RANKL in more detail. [source] High-Density Carrier Accumulation in ZnO Field-Effect Transistors Gated by Electric Double Layers of Ionic LiquidsADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Hongtao Yuan Abstract Very recently, electric-field-induced superconductivity in an insulator was realized by tuning charge carrier to a high density level (1,×,1014 cm,2). To increase the maximum attainable carrier density for electrostatic tuning of electronic states in semiconductor field-effect transistors is a hot issue but a big challenge. Here, ultrahigh density carrier accumulation is reported, in particular at low temperature, in a ZnO field-effect transistor gated by electric double layers of ionic liquid (IL). This transistor, called an electric double layer transistor (EDLT), is found to exhibit very high transconductance and an ultrahigh carrier density in a fast, reversible, and reproducible manner. The room temperature capacitance of EDLTs is found to be as large as 34,µF cm,2, deduced from Hall-effect measurements, and is mainly responsible for the carrier density modulation in a very wide range. Importantly, the IL dielectric, with a supercooling property, is found to have charge-accumulation capability even at low temperatures, reaching an ultrahigh carrier density of 8×1014 cm,2 at 220,K and maintaining a density of 5.5×1014 cm,2 at 1.8,K. This high carrier density of EDLTs is of great importance not only in practical device applications but also in fundamental research; for example, in the search for novel electronic phenomena, such as superconductivity, in oxide systems. [source] Fabrication of aragonite rosette superstructure through the weak interaction between nonionic polymers and Ca2+JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Shuxian Shi Abstract The controlled formation of aragonite by simple method under ambient condition is a big challenge for biomaterial scientists. In this article, we took poly (N -vinyl pyrrolidone) (PVP) as an example to investigate the influence of water-soluble nonionic polymers on the polymorphs of CaCO3 via CO2 diffusion method under ambient pressure and temperature, and found that the existence of PVP molecules favors the formation of aragonite with rosette superstructure. A possible mechanism is proposed that nonionic polymers can be doped into amorphous calcium carbonate (ACC) particles and further participate in the transformation process from ACC to aragonite and then promotes the formation of rosette superstructure through parallel aggregation by crosslinking the aragonite nuclei. The experiments of CaCO3 crystallization in presence of poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) confirmed the mechanism. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Development of a general quantum-chemical descriptor for steric effects: Density functional theory based QSAR study of herbicidal sulfonylurea analoguesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2006Zhen Xi Abstract Quantitative structure-activity relationship (QSAR) analysis has become one of the most effective approaches for optimizing lead compounds and designing new drugs. Although large number of quantum-chemical descriptors were defined and applied successfully, it is still a big challenge to develop a general quantum-chemical descriptor describing the bulk effects more directly and effectively. In this article, we defined a general quantum-chemical descriptor by characterizing the volume of electron cloud for specific substituent using the method of density functional theory. The application of our defined steric descriptors in the QSAR analysis of sulfonylurea analogues resulted in four QSAR models with high quality (the best model: q2 = 0.881, r2 = 0.901, n = 35, s = 0.401, F = 68.44), which indicated that this descriptor may provide an effective way for solving the problem how to directly describe steric effect in quantum chemistry-based QSAR studies. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1571,1576, 2006 [source] Satisfaction of osteoarthritis patients with provided care is not related to the disease-specific quality of lifeJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 3 2009Thomas Rosemann MD PhD Abstract Background, Osteoarthritis (OA) has a high prevalence in primary care. Patient satisfaction is an important indicator for the quality of care provided to OA patients. Little is known about satisfaction of patients with this condition in a primary care setting in Germany. The aim of the study was to assess current satisfaction of patients and reveal possible disease and quality of life related predictors. Methods/Design, Seventy-five German GPs approached 1250 patients with OA consecutively. Sociodemographics, OA-specific quality of life (GERMAN-AIMS2-SF), co-morbidities and depression (using PHQ-9) were assessed. Patient satisfaction was measured by means of the European Task Force on Patient Evaluations of General Practice (EUROPEP) instrument. A stepwise linear regression analysis with the EUROPEP score as dependent variable controlled for the amount of GP visits was performed to assess predictors of satisfaction. Results, A total of 1021 OA patients returned the questionnaire. The adjusted R2 of the final model was 0.270 (P < 0.001). The main predictors were the PHQ-9 score (beta = ,0.372; P < 0.001), age (beta = ,0.185; P < 0.001), living alone (beta = ,0.209; P < 0.001) and number of co-morbidities (beta = ,0.152; P < 0.001). The only disease-related factor which remained as predictor of patient satisfaction was duration of OA (beta = ,0.105; P = 0.008). Discussion, The finding that depression and social factors are more important for patient satisfaction with provided care than disease-related aspects suggests that these factors need to be considered carefully in treatment. This represents a big challenge within an increasingly specialized health care system. The General Practitioner as the regular and first-choice provider of health care seems to be the most appropriate instance who can accomplish this. [source] Numerical Simulation of the Application of NiTi Alloys in Medical TechnologiesPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Daniel Christ Shape memory alloys are nowadays already established as a material which is able to solve exceptional tasks in practical applications. Particularly, its utilization in the field of medical technologies increases steadily. For example micro tools (staple, catheters) and implants (coronary stents) are made out of Nickel-Titanium well known as a basic shape memory alloy. Apart from the advantages like the avoidance of auxiliary components and joints in the system and to utilize the high volume specific work of shape memory alloys, NiTi alloys exhibit a good biocompatibility. This property is necessary with regard to either permanent or temporary implants. To optimize the use of NiTi alloys in the scope of medical technologies, the support of the development of applicable tools by numerical simulations is highly recommended. However the complex material behaviour containing a profoundly thermomechanical coupling poses indeed a big challenge to the material modeling and its implementation into a finite element code. Particularly, the material model proposed by Helm [1] proves to be a firm model containing the most common properties of shape memory alloys, as the pseudoelasticity, the shape memory effect and the two-way effect. In the present contribution the FE modelling of a medical staple used in foot surgery is presented by considering the model of Helm which was investigated by the authors to improve its performance in the finite element method [2]. The foot staple, produced by a group of members of the SFB 459 which is funded by the DFG, avails the shape memory effect to excite the desired clamping effect [3]. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Rise of Supermarkets in Africa: Implications for Agrifood Systems and the Rural PoorDEVELOPMENT POLICY REVIEW, Issue 3 2003Dave D. Weatherspoon The rise of supermarkets in Africa since the mid-1990s is transforming the food retail sector. Supermarkets have spread fast in Southern and Eastern Africa, already proliferating beyond middle-class big-city markets into smaller towns and poorer areas. Supplying supermarkets presents both potentially large opportunities and big challenges for producers. Supermarkets' procurement systems involve purchase consolidation, a shift to specialised wholesalers, and tough quality and safety standards. To meet these requirements, producers have to make investments and adopt new practices. This is hardest for small producers, who risk exclusion from dynamic urban markets increasingly dominated by supermarkets. There is thus an urgent need for development programmes and policies to assist them in adopting the new practices that these procurement systems demand. [source] Web communication services and the PacketIN® application hosting environmentBELL LABS TECHNICAL JOURNAL, Issue 1 2002Yang Chen Large telecommunication customers are migrating their network infrastructure to support new converged services, while containing their operating costs. Deploying converged services on the networks today represents great opportunities to network service providers for new revenue generation. It brings big challenges as well, due to the requirements for a service platform with high capability to deal with the complexity of the network infrastructure, the difficulty of interoperability between different service platforms, and the diversity of signaling protocols and application programming interfaces (APIs). The Lucent PacketIN® application hosting environment (AHE) provides a solution that empowers network service providers to deliver a wide variety of enhanced services over the converged (packet and circuit, wireline and wireless) networks. It enables the creation and deployment of enhanced services on converged networks via the open service platform with interoperability, programmability, scalability, and wide protocol compliance. In particular, a new class of services is presented to demonstrate the transformation of telecommunication services that is enabled through Web presence. This article gives an overview of the PacketIN AHE with the focus on the customer values, the architecture, and enabling capability to deploy advanced applications and services. A new service portal, enterprise communication, is presented as an example of the innovation and implementation enabled by the service enabling environment. The enterprise communication provides Web access to presence information, instant messaging, third-party call management, and location. This convergence of features is enabled by the PacketIN AHE integration of the public switched telephone network (PSTN), session initiation protocol (SIP), and H.323 protocols through standard open APIs. The voice communication protocols are combined with a Web access interface to establish a new Internet presence, while leveraging existing switching products and reusing deployed communication networks and services. © 2002 Lucent Technologies Inc. [source] Addressing Central Nervous System (CNS) Penetration in Drug Discovery: Basics and Implications of the Evolving New ConceptCHEMISTRY & BIODIVERSITY, Issue 11 2009Andreas Reichel Abstract Despite enormous efforts, achieving a safe and efficacious concentration profile in the brain remains one of the big challenges in central nervous system (CNS) drug discovery and development. Although there are multiple reasons, many failures are due to underestimating the complexity of the brain, also in terms of pharmacokinetics (PK). To this day, PK support of CNS drug discovery heavily relies on improving the blood,brain barrier (BBB) permeability in vitro and/or the brain/plasma ratio (Kp) in vivo, even though neither parameter can be reliably linked to pharmacodynamic (PD) and efficacy readouts. While increasing BBB permeability may shorten the onset of drug action, an increase in the total amount in brain may not necessarily increase the relevant drug concentration at the pharmacological target. Since the traditional Kp ratio is based on a crude homogenization of brain tissue, it ignores the compartmentalization of the brain and an increase favors non-specific binding to brain lipids rather than free drug levels. To better link exposure/PK to efficacy/PD and to delineate key parameters, an integrated approach to CNS drug discovery is emerging which distinguishes total from unbound brain concentrations. As the complex nature of the brain requires different compartments to be considered when trying to understand and improve new compounds, several complementary parameters need to be measured in vitro and in vivo, and integrated into a coherent model of brain penetration and distribution. The new paradigm thus concentrates on finding drug candidates with the right balance between free fraction in plasma and brain, and between rate and extent of CNS penetration. Integrating this data into a coherent model of CNS distribution which can be linked to efficacy will allow it to design compounds with an optimal mix in physicochemical, pharmacologic, and pharmacokinetic properties, ultimately mitigating the risk for failures in the clinic. [source] | |||||||||||||||||||