9,520 research outputs found

    Exact and Asymptotic Inference in Clinical Trials with Small Event Rates under Inverse Sampling

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    In this paper we discuss statistical inference for a two-by-two table under inverse sampling, where the total number of cases is fixed by design. We demonstrate that the exact unconditional distributions of some relevant statistics differ from the distributions under conventional sampling, where the sample size is fixed by design. This permits us to define a simple unconditional alternative to Fisher’s exact test. We provide an asymptotic argument including simulations to demonstrate that there is little power-loss associated with the alternative test when the expected response rates are rare. We then apply the method to design a clinical trial in cataract surgery, where a rare side effect occurs in one in one-thousand patients. Objective of the trial is to demonstrate that adjuvant treatment with an antibiotic will reduce this risk to one in two-thousand. We use an inverse sampling design and demonstrate how to set this up in a sequential manner. Particularly simple stopping rules can be defined when using the unconditional alternative to Fisher’s exact test

    Performance of a large limited streamer tube cell in drift mode

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    The performance of a large (3x3 cm2cm^2) streamer tube cell in drift mode is shown. The detector space resolution has been studied using cosmic muons crossing an high precision silicon telescope. The experimental results are compared with a GARFIELD simulation.Comment: 18 pages, 7 figures. Accepted by Nucl. Instr. and Methods

    Plasma Membranes in Psoriatic Cells. A Freeze-fracture Study

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    A freeze-fracture study of affected and unaffected psoriatic skin has demonstrated the presence of marked modification of the plasma membrane in the psoriatic lesion. In the lower layers of the epidermis, an increase of membrane associated particles was observed in many keratinocytes, possibly representing the morphological intramembranous equivalent of changes in the outer cell membrane demonstrated with cytochemical techniques. Furthermore, in the malphighian layer, numerous gap junctions have been found, which may be interpreted as a phenomenon compensating the uncontrolled proliferation, and may represent a point of differentiation between cell proliferation in psoriasis and neoplasia. This technique confirmed the poor tendency to adhesion of keratinocytes in extrajunctional areas, which had already been shown by other morphological techniques

    Blended structural optimization for wire-and-arc additively manufactured beams

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    Current manufacturing techniques in the construction sector are slow, expensive and constrained in terms of architectural shapes. In other manufacturing sectors (such as automotive and aerospace) the use of automated construction systems significantly improved the safety, speed, quality and complexity of products. To realize real-scale structural elements for construction applications without ideally any geometrical constraints either in size or shape, the most suitable manufacturing solution for metallic elements is a directed energy deposition (DED) process referred to as wire-and-arc additive manufacturing (WAAM). The main advantage of WAAM relies on the possibility to create new shapes and forms following the breakthrough design tools for modern architecture as algorithm-aided design. At the same time, the printed part ensures high structural performances with reduced material use with respect to the conventional solution. The study presents a new approach called “blended” structural optimization, which blends topology optimization with basic principles of structural design and manufacturing constraints proper of WAAM technology, towards the realization of new efficient structural elements. The approach is applied to the case study of a I-type stainless steel beam on a multi-storey frame building. The approach could pave the way towards an efficient use of WAAM process to produce a new generation of structurally optimized elements for construction, with a more conscious use of the optimization tools and an efficient application of metal 3D printing

    Genetics, odor perception and food liking: The intriguing role of cinnamon

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    Humans use a repertoire of > 400 olfactory receptors (ORs) to perceive odorants. The sense of smell is a complex trait whereby genetics and environmental factors interplay. To date, still little is known regarding the genetics of smell, even though the high genetic variability of ORs genes has already been demonstrated. Recently a significant association between cinnamon odorant recognition and the rs317787 polymorphism, located in a cluster of OR genes, has been described. Based on this data, here, we replicated the effect of the same variant (rs317787) on cinnamon odorant identification as well as looked at any possible association with liking for wine whose bouquet frequently smells of cinnamon. Our analysis in a cohort of individuals from two Italian genetic isolates confirmed that rs317787-T allele is associated with an improved cinnamon detection (p-value 5.18 7 10 1206, n = 971) but also with a greater liking for red wine (p-value 0.017, n = 2374). Present results further confirm the association of rs31778 SNP and cinnamon odorants detection and provide additional details about the role of the ORs genes in food liking. Overall, our work contributes to better deciphering the genetic basis of smell and food liking aimed at a more in-depth elucidation of the role of the ORs genes

    Mechanical Systems: Symmetry and Reduction

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    Reduction theory is concerned with mechanical systems with symmetries. It constructs a lower dimensional reduced space in which associated conservation laws are taken out and symmetries are \factored out" and studies the relation between the dynamics of the given system with the dynamics on the reduced space. This subject is important in many areas, such as stability of relative equilibria, geometric phases and integrable systems

    Long-term seismometric monitoring of the two towers of Bologna (Italy): Modal frequencies identification and effects due to traffic induced vibrations

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    The rise of human activities and the constant increase of vehicles traffic in the cities, and in particular of heavy vehicles such as buses and trucks, causes continues ambient vibrations that can detrimentally affect the conservation of built artifacts, especially historical constructions. The effects of urban vibrations on buildings and monuments are far from being fully investigated. In general, peak levels of traffic-induced vibrations are rarely high enough to be the main cause of heavy structural damages. On the other hand, they contribute to the process of deterioration by adding extra stresses\u2014through fatigue damage accumulation occurring as a result of long periods of exposure to low levels of vibration\u2014or by contributing to soil densification\u2014which can lead to the settlement of building foundations. As such, the estimation of threshold levels above which traffic-induced vibrations may cause damages to monumental buildings requires specific studies including long-time monitoring campaigns. Data from experimental campaign can, indeed, be used to extract information on the variation of dynamic properties of buildings, thus providing valuable pieces of information for a complete knowledge to plan effective preservation interventions. The present work aims to identify the effects of traffic induced urban vibrations on the two Towers of Bologna, particularly prone to fatigue-related damages and close to a high transit of vehicles, through a preliminary analysis of data from several dynamic monitoring campaigns conducted during the last years

    The driving forces of the biotic processes along an offshore gradient in the Ligurian basin (Portofino Promontory) during 2008

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    The marine coastal area of the Portofino Promontory, located in the North-East side of the Ligurian basin (Mediterranean Sea), has been studied since 1980’s to identify its main ecological characteristics. The large physical, chemical and biological dataset available for this site (LTER sites) represents a powerful tool for the reliable reconstruction of seasonal cycles and allow the differentiation of regular and recurrent patterns from occasional and exceptional events. This long-term monitoring reveled an increases in the average monthly temperature along the water column in the last 10 years compare with the previous decade (1985-1995), with a high inter-annual variability and some specific episodic occurrence of thermal anomalies. The physical features of the water column seems to have a strict relation with the phytoplankton biomass fluctuations. A detailed study of 2008 intended to analyze a wider area, in order to compare the driving forces influencing the development of biotic process along an offshore gradient

    Linomide blocks angiogenesis by breast carcinoma vascular endothelial growth factor transfectants.

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    The blocking of angiogenesis provides a novel therapeutic target to inhibit tumour spreading. In this study, we investigated the effect of linomide on angiogenesis induced in vivo by highly angiogenic breast carcinoma cells. The rabbit cornea was used to assess neovascular growth in the absence of a tumour mass. MCF-7 cells stably transfected with the cDNA encoding for vascular endothelial growth factor 121 (VEGF121) (V12 clone) were used to elicit a potent VEGF-dependent corneal angiogenesis. After tumour cell implant, albino rabbits received 100 mg kg(-1) day(-1) linomide for 5 consecutive days. Daily observation of neovascular progression indicated that linomide blocked angiogenesis. The antiangiogenic effect of linomide was apparent within 48 h from the beginning of the treatment and was both angiosuppressive and angiostatic. The block of neovascular growth lasted over 10 days from treatment suspension, and preformed vessels, which had regressed, remained dormant, suggesting the persistence of unfavourable conditions for capillary progression. Linomide (50-200 microg ml[-1]) was not cytotoxic in vitro on resting capillary endothelial cells but blocked endothelial cell replication induced by VEGF. Our data indicate that linomide can efficiently and persistently block VEGF-dependent angiogenesis in vivo in the absence of a growing tumour mass. These data suggest that linomide could be a chemopreventive drug in breast cancer patients and a valuable tool in clinical settings in which metastatic spreading occurs in the absence of a detectable tumour mass
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