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Precise Assessment (precise + assessment)
Selected AbstractsDo patents over-compensate innovators?ECONOMIC POLICY, Issue 52 2007Vincenzo Denicolò SUMMARY Do patents over-compensate innovators? Is the current level of patent protection too high or too low? To address this issue, this paper reformulates the theoretical analysis of the optimal level of patent protection to take into account the empirical findings of the innovation production function literature. This literature finds a strong relationship between R&D spending and inventions and estimates an elasticity of the supply of inventions of 0.5 or more. The paper then assesses the current level of patent protection, exploiting estimates of the private and social returns to R&D taken from the empirical literature and other available sources. Although more research is needed for a more precise assessment, the evidence available suggests that patents do not over-compensate innovators. ,Vincenzo Denicolò [source] Exploration of the functional hierarchy of the basal layer of human epidermis at the single-cell level using parallel clonal microcultures of keratinocytesEXPERIMENTAL DERMATOLOGY, Issue 4 2010Nicolas O. Fortunel Please cite this paper as: Exploration of the functional hierarchy of the basal layer of human epidermis at the single-cell level using parallel clonal microcultures of keratinocytes. Experimental Dermatology 2010. Abstract:, The basal layer of human epidermis contains both stem cells and keratinocyte progenitors. Because of this cellular heterogeneity, the development of methods suitable for investigations at a clonal level is dramatically needed. Here, we describe a new method that allows multi-parallel clonal cultures of basal keratinocytes. Immediately after extraction from tissue samples, cells are sorted by flow cytometry based on their high integrin-,6 expression and plated individually in microculture wells. This automated cell deposition process enables large-scale characterization of primary clonogenic capacities. The resulting clonal growth profile provided a precise assessment of basal keratinocyte hierarchy, as the size distribution of 14-day-old clones ranged from abortive to highly proliferative clones containing 1.7 × 105 keratinocytes (17.4 cell doublings). Importantly, these 14-day-old primary clones could be used to generate three-dimensional reconstructed epidermis with the progeny of a single cell. In long-term cultures, a fraction of highly proliferative clones could sustain extensive expansion of >100 population doublings over 14 weeks and exhibited long-term epidermis reconstruction potency, thus fulfilling candidate stem cell functional criteria. In summary, parallel clonal microcultures provide a relevant model for single-cell studies on interfollicular keratinocytes, which could be also used in other epithelial models, including hair follicle and cornea. The data obtained using this system support the hierarchical model of basal keratinocyte organization in human interfollicular epidermis. [source] Sensitivity analysis of snow patterns in Swiss ski resorts to shifts in temperature, precipitation and humidity under conditions of climate changeINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2009Bastienne Uhlmann Abstract The value of snow as a resource has considerably increased in Swiss mountain regions, in particular in the context of winter tourism. In the perspective of a warming climate, it is thus important to quantify the potential changes in snow amount and duration that could have large repercussions on the economy of ski resorts. Because of the fine spatial variability of snow, the use of a Surface Energy Balance Model (SEBM) is adequate to simulate local snow cover evolution. A perturbation method has been developed to generate plausible future meteorological input data required for SEBM simulations in order to assess the changes in snow cover patterns. Current and future snow depths have also been simulated within the ski areas themselves. The results show a large decrease of the snow depths and duration, even at high elevation in a warmer climate and emphasize the sensitivity of snow to topographical characteristics of the resorts. The most vulnerable areas would be the Western regions of Switzerland or the Eastern Prealps whereas the Central Alps or Valais would be less affected. The study highlights the fact that not only the altitude of a domain but also its exposure, localization inland and slope gradients need to be taken into account when evaluating current and future snow depths. This method enables a precise assessment of the snow pattern over a small area. Copyright © 2008 Royal Meteorological Society [source] Design and creation of an experimental program of advanced training in reconstructive microsurgeryMICROSURGERY, Issue 6 2006Andrés R. Lorenzo M.D. In this study, we design an experimental protocol for the purpose of enhancing performance in training in microsurgery. It is based on five free tissue transfer exercises in rat (epigastric cutaneous flap, saphenous fasciocutaneous flap, epigastric neurovascular flap, saphenous muscular flap, and hindlimb replantation), which simulate the principal clinical procedures of reconstructive microsurgery. The first part of the study consists of an anatomical review of the flaps of 5 rats and in the second part we have carried out the free transfer of flaps on 25 rats divided into 5 groups. To differentiate between them, we have created a mathematical function, referred to as difficulty in a microsurgical exercise, which has enabled us to establish a scale of progression for training, ranging form the easiest to the most difficult. As a conclusion, we believe that this protocol is a useful instrument as it allows for a more precise assessment of microsurgical capacity due to enhanced accuracy in the reproduction of global procedures and the fact that the quantification of progress in training is based on clinical monitoring after 7 days. © 2006 Wiley-Liss, Inc. Microsurgery, 2006. [source] Management of critically ill children with traumatic brain injuryPEDIATRIC ANESTHESIA, Issue 6 2008GILLES A. ORLIAGUET MD PhD Summary The management of critically ill children with traumatic brain injury (TBI) requires a precise assessment of the brain lesions but also of potentially associated extra-cranial injuries. Children with severe TBI should be treated in a pediatric trauma center, if possible. Initial assessment relies mainly upon clinical examination, trans-cranial Doppler ultrasonography and body CT scan. Neurosurgical operations are rarely necessary in these patients, except in the case of a compressive subdural or epidural hematoma. On the other hand, one of the major goals of resuscitation in these children is aimed at protecting against secondary brain insults (SBI). SBI are mainly because of systemic hypotension, hypoxia, hypercarbia, anemia and hyperglycemia. Cerebral perfusion pressure (CPP = mean arterial blood pressure , intracranial pressure: ICP) should be monitored and optimized as soon as possible, taking into account age-related differences in optimal CPP goals. Different general maneuvers must be applied in these patients early during their treatment (control of fever, avoidance of jugular venous outflow obstruction, maintenance of adequate arterial oxygenation, normocarbia, sedation,analgesia and normovolemia). In the case of increased ICP and/or decreased CPP, first-tier ICP-specific treatments may be implemented, including cerebrospinal fluid drainage, if possible, osmotic therapy and moderate hyperventilation. In the case of refractory intracranial hypertension, second-tier therapy (profound hyperventilation with PaCO2 < 35 mmHg, high-dose barbiturates, moderate hypothermia, decompressive craniectomy) may be introduced, after a new cerebral CT scan. [source] Designing an accelerated degradation experiment by optimizing the estimation of the percentileQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 3 2003Hong-Fwu Yu Abstract Degradation tests are widely used to assess the reliability of highly reliable products which are not likely to fail under traditional life tests or accelerated life tests. However, for some highly reliable products, the degradation may be very slow and hence it is impossible to have a precise assessment within a reasonable amount of testing time. In such cases, an alternative is to use higher stresses to extrapolate the product's reliability at the design stress. This is called an accelerated degradation test (ADT). In conducting an ADT, several decision variables, such s the inspection frequency, sample size and termination time, at each stress level are influential on the experimental efficiency. An inappropriate choice of these decision variables not only wastes experimental resources but also reduces the precision of the estimation of the product's reliability at the use condition. The main purpose of this paper is to deal with the problem of designing an ADT. By using the criterion of minimizing the mean-squared error of the estimated 100th percentile of the product's lifetime distribution at the use condition subject to the constraint that the total experimental cost does not exceed a predetermined budget, a nonlinear integer programming problem is built to derive the optimal combination of the sample size, inspection frequency and the termination time at each stress level. A numerical example is provided to illustrate the proposed method. Copyright © 2003 John Wiley & Sons, Ltd. [source] Distribution of Aggregate Utility Using Stochastic Elements of Additive Multiattribute Utility ModelsDECISION SCIENCES, Issue 2 2000Herbert Moskowitz ABSTRACT Conventionally, elements of a multiattribute utility model characterizing a decision maker's preferences, such as attribute weights and attribute utilities, are treated as deterministic, which may be unrealistic because assessment of such elements can be imprecise and erroneous, or differ among a group of individuals. Moreover, attempting to make precise assessments can be time consuming and cognitively demanding. We propose to treat such elements as stochastic variables to account for inconsistency and imprecision in such assessments. Under these assumptions, we develop procedures for computing the probability distribution of aggregate utility for an additive multiattribute utility function (MAUF), based on the Edgeworth expansion. When the distributions of aggregate utility for all alternatives in a decision problem are known, stochastic dominance can then be invoked to filter inferior alternatives. We show that, under certain mild conditions, the aggregate utility distribution approaches normality as the number of attributes increases. Thus, only a few terms from the Edgeworth expansion with a standard normal density as the base function will be sufficient for approximating an aggregate utility distribution in practice. Moreover, the more symmetric the attribute utility distributions, the fewer the attributes to achieve normality. The Edgeworth expansion thus can provide a basis for a computationally viable approach for representing an aggregate utility distribution with imprecisely specified attribute weights and utilities assessments (or differing weights and utilities across individuals). Practical guidelines for using the Edgeworth approximation are given. The proposed methodology is illustrated using a vendor selection problem. [source] | |||||||||||||