347 research outputs found

    An Asian darkling beetle, Ceropria induta (Wiedemann), established in Florida (Coleoptera: Tenebrionidae)

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    Specimen records for an adventive darkling beetle, Ceropria induta (Wiedemann) (Coleoptera: Tenebrionidae; Diaperinae) show that this Asian insect has become established in southern Florida, USA. Illustrations and a diagnosis of the beetle are provided, with notes on habitats and possible polyporaceous hosts, and the genus is incorporated into a key to the related North American taxa

    Common Scaling Patterns in Intertrade Times of U. S. Stocks

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    We analyze the sequence of time intervals between consecutive stock trades of thirty companies representing eight sectors of the U. S. economy over a period of four years. For all companies we find that: (i) the probability density function of intertrade times may be fit by a Weibull distribution; (ii) when appropriately rescaled the probability densities of all companies collapse onto a single curve implying a universal functional form; (iii) the intertrade times exhibit power-law correlated behavior within a trading day and a consistently greater degree of correlation over larger time scales, in agreement with the correlation behavior of the absolute price returns for the corresponding company, and (iv) the magnitude series of intertrade time increments is characterized by long-range power-law correlations suggesting the presence of nonlinear features in the trading dynamics, while the sign series is anti-correlated at small scales. Our results suggest that independent of industry sector, market capitalization and average level of trading activity, the series of intertrade times exhibit possibly universal scaling patterns, which may relate to a common mechanism underlying the trading dynamics of diverse companies. Further, our observation of long-range power-law correlations and a parallel with the crossover in the scaling of absolute price returns for each individual stock, support the hypothesis that the dynamics of transaction times may play a role in the process of price formation.Comment: 8 pages, 5 figures. Presented at The Second Nikkei Econophysics Workshop, Tokyo, 11-14 Nov. 2002. A subset appears in "The Application of Econophysics: Proceedings of the Second Nikkei Econophysics Symposium", editor H. Takayasu (Springer-Verlag, Tokyo, 2003) pp.51-57. Submitted to Phys. Rev. E on 25 June 200

    Developments in unsteady pipe flow friction modelling

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    This paper reviews a number of unsteady friction models for transient pipe flow. Two distinct unsteady friction models, the Zielke and the Brunone models, are investigated in detail. The Zielke model, originally developed for transient laminar flow, has been selected to verify its effectiveness for "low Reynolds number" transient turbulent flow. The Brunone model combines local inertia and wall friction unsteadiness. This model is verified using the Vardy's analytically deduced shear decay coefficient C* to predict the Brunone's friction coefficient k rather than use the traditional trial and error method for estimating k. The two unsteady friction models have been incorporated into the method of characteristics water hammer algorithm. Numerical results from the quasi-steady friction model and the Zielke and the Brunone unsteady friction models are compared with results of laboratory measurements for water hammer cases with laminar and low Reynolds number turbulent flows. Conclusions about the range of validity for the three friction models are drawn. In addition, the convergence and stability of these models are addressed.Anton Bergant, Angus Ross Simpson, John Vìtkovsk

    Imaging assessment and clinical significance of pneumatosis in adult patients.

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    Gas detection in the bowel wall and in portomesenteric venous vessels in adults has long been related to intestinal infarction and poor outcome; many case reports have shown that pneumatosis may be associated with a large variety of pathological situations, ranging from absolutely benign and asymptomatic forms to abdominal catastrophes. Several studies have been conducted on this topic with different conclusions, probably due to differences in population so that the clinical value of these signs is still questioned. Intestinal pneumatosis, especially if presenting with a band-like pattern and if associated with portomesenteric vein gas, when observed in an acute abdominal setting should raise the suspicion of mesenteric infarct and prompt a careful search for other signs of intestinal involvement, so as not to miss cases of life-threatening intestinal infarct or allow them to further evolve into extensive necrosis with worse prognosis. In this review we illustrate the most relevant aspects of these debated but significant radiological signs

    Executive function abnormalities in pathological gamblers

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    Background: Pathological gambling (PG) is an impulse control disorder characterized by persistent and maladaptive gambling behaviors with disruptive consequences for familial, occupational and social functions. The pathophysiology of PG is still unclear, but it is hypothesized that it might include environmental factors coupled with a genetic vulnerability and dysfunctions of different neurotransmitters and selected brain areas. Our study aimed to evaluate a group of patients suffering from PG by means of some neuropsychological tests in order to explore the brain areas related to the disorder. Methods: Twenty outpatients (15 men, 5 women), with a diagnosis of PG according to DSM-IV criteria, were included in the study and evaluated with a battery of neuropsychological tests: the Wisconsin Card Sorting Test (WCST), the Wechsler Memory Scale revised (WMS-R) and the Verbal Associative Fluency Test (FAS). The results obtained in the patients were compared with normative values of matched healthy control subjects. Results: The PG patients showed alterations at the WCST only, in particular they had a great difficulty in finding alternative methods of problem-solving and showed a decrease, rather than an increase, in efficiency, as they progressed through the consecutive phases of the test. The mean scores of the other tests were within the normal range. Conclusion: Our findings showed that patients affected by PG, in spite of normal intellectual, linguistic and visual-spatial abilities, had abnormalities emerging from the WCST, in particular they could not learn from their mistakes and look for alternative solutions. Our results would seem to confirm an altered functioning of the prefrontal areas which might provoke a sort of cognitive "rigidity" that might predispose to the development of impulsive and/or compulsive behaviors, such as those typical of PG. © 2008 Marazziti et al; licensee BioMed Central Ltd

    Precision and progress: minimally invasive surgery in gynaecologic cancer treatment

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    Minimally invasive surgery (MIS), which comprises laparoscopy, robotic surgery, and vaginal transluminal natural endoscopic surgery (vNOTES), has gained notoriety in the setting of many gynaecologic diseases, including endometrial, ovarian, and cervical cancers. Over the years, several studies have conducted comparisons between MIS and laparotomic surgery. The predominant aspects of these techniques include less intraoperative bleeding, shorter hospitalization, accelerated postoperative recovery and lower incidence of peri-and postoperative adverse events. However, costs and operative time remain high. Articles comparing different minimally invasive surgical procedures for the management of gynaecologic cancer were reviewed. Although several articles have pointed out that the use of the surgical approach by MIS has not shown substantial differences in survival compared with laparotomy and has manifested excellent peri-and postoperative outcomes for endometrial cancer, the relevance of minimally invasive surgery for cervical and ovarian cancer remains controversial. Incipient indications suggest laparoscopic cytoreduction as an emerging procedure for appropriately selected patients following neoadjuvant chemotherapy treatment. Several scientific evidence have attested to the improved clinical parameters associated with the adoption of a minimally invasive surgical approach compared with open procedures. The preeminent goal of minimally invasive surgery should aim at optimizing oncologic outcomes and improving the health status of patients

    Plasma microglial-derived extracellular vesicles are increased in frail patients with Mild Cognitive Impairment and exert a neurotoxic effect

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    Extracellular vesicles (EVs) are mediators of cellular communication that can be released by almost all cell types in both physiological and pathological conditions and are present in most biological fluids. Such characteristics make them attractive in the research of biomarkers for age-related pathological conditions. Based on this, the aim of the present study was to examine the changes in EV concentration and size in the context of frailty, a geriatric syndrome associated with a progressive physical and cognitive decline. Specifically, total EVs and neural and microglial-derived EVs (NDVs and MDVs respectively) were investigated in plasma of frail and non-frail controls (CTRL), mild cognitive impairment (MCI) subjects, and in Alzheimer's disease (AD) patients. Results provided evidence that AD patients displayed diminished NDV concentration (3.61 x 10(9) +/- 1.92 x 10(9) vs 7.16 x 10(9) +/- 4.3 x 10(9) particles/ml) and showed high diagnostic performance. They are able to discriminate between AD and CTRL with an area under the curve of 0.80, a sensitivity of 78.95% and a specificity of 85.7%, considering the cut-off of 5.27 x 10(9) particles/ml. Importantly, we also found that MDV concentration was increased in frail MCI patients compared to CTRL (5.89 x 10(9) +/- 3.98 x 10(9) vs 3.16 x 10(9) +/- 3.04 x 10(9) particles/ml, P < 0.05) and showed high neurotoxic effect on neurons. MDV concentration discriminate frail MCI vs non-frail CTRL (AUC = 0.76) with a sensitivity of 80% and a specificity of 70%, considering the cut-off of 2.69 x 10(9) particles/ml. Altogether, these results demonstrated an alteration in NDV and MDV release during cognitive decline, providing important insight into the role of EVs in frailty status
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