Experimental research on impacts of dimensionality on clustering algorithms

Experiments are carried out on datasets with different dimensions selected from UCI datasets by using two classical clustering algorithms. The results of the experiments indicate that when the dimensionality of the real dataset is less than or equal to 30, the clustering algorithms based on distance are effective. For high-dimensional datasets - dimensionality is greater than 30, the clustering algorithms are of weaknesses, even if we use dimension reduction methods, such as Principal Component Analysis (PCA). ©2010 IEEE

A Novel Remaining Useful Estimation Model to Assist Asset Renewal Decisions Applied to the Brazilian Electric Sector

Assets deteriorate over time, as well as being covered, corroded, or becoming old in less obvious ways. Maintenance can extend the remaining useful life (RUL) of an asset system, but sooner or later it must surely be replaced. In this study, we propose a new RUL estimation methodology to assist in decision making for the maintenance and replacement of assets from prioritizing equipment in a renovation plan. Our methodology uses advanced data analysis techniques that consider multiple competing criteria with the goal of maximizing values of the asset throughout its life cycle, while considering the rules of remuneration and service quality of the current regulation, as well as the values at risk according to the decisions and actions taken. Experimental results with real datasets show the efficiency of the proposed approach. Finally, this work also presents the development of an analytical tool to optimize asset renewal decisions applying the RUL estimation methodology proposed and its application to the Brazilian electric sector

Effect of parasympathetic stimulation on brain activity during appraisal of fearful expressions

Autonomic nervous system activity is an important component of human emotion. Mental processes influence bodily physiology, which in turn feeds back to influence thoughts and feelings. Afferent cardiovascular signals from arterial baroreceptors in the carotid sinuses are processed within the brain and contribute to this two-way communication with the body. These carotid baroreceptors can be stimulated non-invasively by externally applying focal negative pressure bilaterally to the neck. In an experiment combining functional neuroimaging (fMRI) with carotid stimulation in healthy participants, we tested the hypothesis that manipulating afferent cardiovascular signals alters the central processing of emotional information (fearful and neutral facial expressions). Carotid stimulation, compared with sham stimulation, broadly attenuated activity across cortical and brainstem regions. Modulation of emotional processing was apparent as a significant expression-by-stimulation interaction within left amygdala, where responses during appraisal of fearful faces were selectively reduced by carotid stimulation. Moreover, activity reductions within insula, amygdala, and hippocampus correlated with the degree of stimulation-evoked change in the explicit emotional ratings of fearful faces. Across participants, individual differences in autonomic state (heart rate variability, a proxy measure of autonomic balance toward parasympathetic activity) predicted the extent to which carotid stimulation influenced neural (amygdala) responses during appraisal and subjective rating of fearful faces. Together our results provide mechanistic insight into the visceral component of emotion by identifying the neural substrates mediating cardiovascular influences on the processing of fear signals, potentially implicating central baroreflex mechanisms for anxiolytic treatment targets

HIV Serostatus and Tumor Differentiation Among Patients with Cervical Cancer at Bugando Medical Centre.

Evidence for the association between Human immunodeficiency virus infection and cervical cancer has been contrasting, with some studies reporting increased risk of cervical cancer among HIV positive women while others report no association. Similar evidence from Tanzania is scarce as HIV seroprevalence among cervical cancer patients has not been rigorously evaluated. The purpose of this study was to determine the association between HIV and tumor differentiation among patients with cervical cancer at Bugando Medical Centre and Teaching Hospital in Mwanza, North-Western Tanzania. This was a descriptive analytical study involving suspected cervical cancer patients seen at the gynaecology outpatient clinic and in the gynaecological ward from November 2010 to March 2011. A total of 91 suspected cervical cancer patients were seen during the study period and 74 patients were histologically confirmed with cervical cancer. The mean age of those confirmed of cervical cancer was 50.5 ± 12.5 years. Most patients (39 of the total 74-52.7%) were in early disease stages (stages IA-IIA). HIV infection was diagnosed in 22 (29.7%) patients. On average, HIV positive women with early cervical cancer disease had significantly more CD4+ cells than those with advanced disease (385.8 ± 170.4 95% CI 354.8-516.7 and 266.2 ± 87.5, 95% CI 213.3-319.0 respectively p = 0.042). In a binary logistic regression model, factors associated with HIV seropositivity were ever use of hormonal contraception (OR 5.79 95% CI 1.99-16.83 p = 0.001), aged over 50 years (OR 0.09 95% CI 0.02-0.36 p = 0.001), previous history of STI (OR 3.43 95% CI 1.10-10.80 p = 0.035) and multiple sexual partners OR 5.56 95% CI 1.18-26.25 p = 0.030). Of these factors, only ever use of hormonal contraception was associated with tumor cell differentiation (OR 0.16 95% CI 0.06-0.49 p = 0.001). HIV seropositivity was weakly associated with tumor cell differentiation in an unadjusted analysis (OR 0.21 95% CI 0.04-1.02 p = 0.053), but strong evidence for the association was found after adjusting for ever use of hormonal contraception with approximately six times more likelihood of HIV infection among women with poorly differentiated tumor cells compared to those with moderately and well differentiated cells (OR 5.62 95% CI 1.76-17.94 p = 0.004).\ud Results from this study setting suggest that HIV is common among cervical cancer patients and that HIV seropositivity may be associated with poor tumour differentiation. Larger studies in this and similar settings with high HIV prevalence and high burden of cervical cancer are required to document this relationship

The "Clubs against Drugs" program in Stockholm, Sweden: two cross-sectional surveys examining drug use among staff at licensed premises

<p>Abstract</p> <p>Background</p> <p>The objective of this study is to examine self-reported drug use among staff at licensed premises, types of drugs used, attitudes towards drugs, and observed drug use among guests. Results are presented from two measurement points (in 2001 and 2007/08). This study was carried out within the framework of the "Clubs against Drugs" program, which is a community-based multi-component intervention targeting licensed premises in Stockholm, Sweden.</p> <p>Methods</p> <p>Two cross-sectional surveys were conducted, the first in 2001 and the second in 2007/08. Staff at licensed premises attending server training were asked to participate in the anonymous survey. A survey was administered in a classroom setting and consisted of four sections: 1) demographics, 2) respondents' own drug use experience, 3) respondents' attitudes towards drug use, and 4) observed drug use among guests at licensed premises.</p> <p>Results</p> <p>Data were collected from 446 staff in 2001 and 677 staff in 2007/08. The four most commonly used drugs among staff were cannabis, cocaine, amphetamine, and ecstasy. The highest rates of drug use were reported by staff in the two youngest age groups, i.e., those younger than 25 and those between the ages of 25 and 29. In 2007/08 staff reported significantly lower rates of drug use than staff in 2001. Last year drug use for the sample in 2007/08 was 19% compared to 27% for the 2001 sample. While drug-using staff compared to non drug-using staff reported more observations of drug use among guests, they were less inclined to intervene. Overall, staff reported restrictive attitudes towards drugs.</p> <p>Conclusions</p> <p>The prevalence of life-time and last year drug use among staff at licensed premises is high compared to the general population in Sweden. Lower rates of self-reported drug use among staff were reported in 2007/08. The results of this study highlight that staff at licensed premises represent an important target population in club drug prevention programs.</p

The order of the quantum chromodynamics transition predicted by the standard model of particle physics

We determine the nature of the QCD transition using lattice calculations for physical quark masses. Susceptibilities are extrapolated to vanishing lattice spacing for three physical volumes, the smallest and largest of which differ by a factor of five. This ensures that a true transition should result in a dramatic increase of the susceptibilities.No such behaviour is observed: our finite-size scaling analysis shows that the finite-temperature QCD transition in the hot early Universe was not a real phase transition, but an analytic crossover (involving a rapid change, as opposed to a jump, as the temperature varied). As such, it will be difficult to find experimental evidence of this transition from astronomical observations.Comment: 7 pages, 4 figure

The Human Fungal Pathogen Cryptococcus neoformans Escapes Macrophages by a Phagosome Emptying Mechanism That Is Inhibited by Arp2/3 Complex-Mediated Actin Polymerisation

The lysis of infected cells by disease-causing microorganisms is an efficient but risky strategy for disseminated infection, as it exposes the pathogen to the full repertoire of the host's immune system. Cryptococcus neoformans is a widespread fungal pathogen that causes a fatal meningitis in HIV and other immunocompromised patients. Following intracellular growth, cryptococci are able to escape their host cells by a non-lytic expulsive mechanism that may contribute to the invasion of the central nervous system. Non-lytic escape is also exhibited by some bacterial pathogens and is likely to facilitate long-term avoidance of the host immune system during latency. Here we show that phagosomes containing intracellular cryptococci undergo repeated cycles of actin polymerisation. These actin ‘flashes’ occur in both murine and human macrophages and are dependent on classical WASP-Arp2/3 complex mediated actin filament nucleation. Three dimensional confocal imaging time lapse revealed that such flashes are highly dynamic actin cages that form around the phagosome. Using fluorescent dextran as a phagosome membrane integrity probe, we find that the non-lytic expulsion of Cryptococcus occurs through fusion of the phagosome and plasma membranes and that, prior to expulsion, 95% of phagosomes become permeabilised, an event that is immediately followed by an actin flash. By using pharmacological agents to modulate both actin dynamics and upstream signalling events, we show that flash occurrence is inversely related to cryptococcal expulsion, suggesting that flashes may act to temporarily inhibit expulsion from infected phagocytes. In conclusion, our data reveal the existence of a novel actin-dependent process on phagosomes containing cryptococci that acts as a potential block to expulsion of Cryptococcus and may have significant implications for the dissemination of, and CNS invasion by, this organism.\ud \u

Languages cool as they expand: Allometric scaling and the decreasing need for new words

We analyze the occurrence frequencies of over 15 million words recorded in millions of books published during the past two centuries in seven different languages. For all languages and chronological subsets of the data we confirm that two scaling regimes characterize the word frequency distributions, with only the more common words obeying the classic Zipf law. Using corpora of unprecedented size, we test the allometric scaling relation between the corpus size and the vocabulary size of growing languages to demonstrate a decreasing marginal need for new words, a feature that is likely related to the underlying correlations between words. We calculate the annual growth fluctuations of word use which has a decreasing trend as the corpus size increases, indicating a slowdown in linguistic evolution following language expansion. This ‘‘cooling pattern’’ forms the basis of a third statistical regularity, which unlike the Zipf and the Heaps law, is dynamical in nature