Independent Factor Autoregressive Conditional Density Model

In this article, we propose a novel Independent Factor Autoregressive Conditional Density (IFACD) model able to generate time-varying higher moments using an independent factor setup. Our proposed framework incorporates dynamic estimation of higher comovements and feasible portfolio representation within a non-elliptical multivariate distribution. We report an empirical application, using returns data from 14 MSCI equity index iShares for the period 1996 to 2010, and we show that the IFACD model provides superior VaR forecasts and portfolio allocations with respect to the Conditionally Heteroskedastic Independent Component Analysis of Generalized Orthogonal (CHICAGO) and DCC models

Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals

We study the Kondo effect in three-dimensional (3D) Dirac materials and Weyl semimetals. We find the scaling of the Kondo temperature with respect to the doping n and the coupling J between the moment of the magnetic impurity and the carriers of the semimetal. We consider the interplay of long-range scalar disorder and Kondo screening and find that it causes the Kondo effect to be characterized not by a Kondo temperature, but by a distribution of Kondo temperatures with features that cause the appearance of strong non-Fermi-liquid behavior. We then consider the effect of Kondo screening, and of the interplay of Kondo screening and long-range scalar disorder, on the transport properties of Weyl semimetals. Finally, we compare the properties of the Kondo effect in 3D and 2D Dirac materials such as graphene and topological insulators

Sexually Dimorphic Effects of Aging on Rat Somatotropes and Lactotropes

During the aging process modified functions of hypothalamic factors may cause sexually dimorphic changes in pituitary somatotropes and lactotropes. To test this hypothesis, pituitary tissue from young adult (4 months) and old (20-22 months) male and female rats was labeled immunocytochemically for growth hormone (GH) and prolactin (PRL). The total amount of immunoreactive material as well as the total area and number of immunoreactive structures were evaluated. With increasing age the intracellular GH content was moderately increased in male and decreased in female rats. An age-dependent PRL increase, due both to increased cell number and intracellular hormone content, was present only in female rats. The amount of GH- and PRL-immunoreactive material, distributed into classes of increasing density, differed both between sex and age groups. Our results indicate that the aging process of the somatotrope and lactotrope cell populations in rats appears to be different in the two sexe

Structural behaviour of copper chloride catalysts during the chlorination of CO to phosgene

The interaction of CO with an attapulgite-supported Cu(II)Cl2 catalyst has been examined in a micro-reactor arrangement. CO exposure to the dried, as-received catalyst at elevated temperatures leads to the formation of CO2 as the only identifiable product. However, phosgene production can be induced by a catalyst pre-treatment where the supported Cu(II)Cl2 sample is exposed to a diluted stream of chlorine. Subsequent CO exposure at ~ 370°C then leads to phosgene production. In order to investigate the origins of this atypical set of reaction characteristics, a series of x-ray absorption experiments were performed that were supplemented by DFT calculations. XANES measurements establish that at the elevated temperatures connected with phosgene formation, the catalyst is comprised of Cu+ and a small amount of Cu2+. Moreover, the data show that unique to the chlorine pre-treated sample, CO exposure at elevated temperature results in a short-lived oxidation of the copper. On the basis of calculated CO adsorption energies, DFT calculations indicate that a mixed Cu+/Cu2+ catalyst is required to support CO chemisorption

Coexistence of amplitude and frequency modulations in intracellular calcium dynamics

The complex dynamics of intracellular calcium regulates cellular responses to information encoded in extracellular signals. Here, we study the encoding of these external signals in the context of the Li-Rinzel model. We show that by control of biophysical parameters the information can be encoded in amplitude modulation, frequency modulation or mixed (AM and FM) modulation. We briefly discuss the possible implications of this new role of information encoding for astrocytes.Comment: 4 pages, 4 figure

The effects of continuous positive airway pressure therapy withdrawal on cardiac repolarization: data from a randomized controlled trial†

Aims The preliminary evidence supports an association between obstructive sleep apnoea (OSA), disturbed cardiac repolarization, and consequent cardiac dysrhythmias. The aim of the current trial was to assess the effects of continuous positive airway pressure (CPAP) therapy withdrawal on the measures of cardiac repolarization in patients with OSA. Methods and results Forty-one OSA patients established on CPAP treatment were randomized to either CPAP withdrawal (subtherapeutic CPAP) or continue therapeutic CPAP for 2 weeks. Polysomnography was performed, and indices of cardiac repolarization (QTc, TpTec intervals) and dispersion of repolarization (TpTe/QT ratio) were derived from 12-lead electrocardiography (ECG) at baseline and 2 weeks. Continuous positive airway pressure withdrawal led to a recurrence of OSA. Compared with therapeutic CPAP, subtherapeutic CPAP for 2 weeks was associated with a significant increase in the length of the QTc and TpTec intervals (mean difference between groups 21.4 ms, 95% CI 11.3-1.6 ms, P < 0.001 and 14.4 ms, 95% CI 7.2-21.5 ms, P < 0.001, respectively) and in the TpTe/QT ratio (mean difference between groups 0.02, 95% CI 0.00-0.03, P = 0.020). There was a statistically significant correlation between the change in apnoea/hypopnoea index (AHI) from baseline, and both the change in the QTc interval and the TpTec interval (r = 0.60, 95% CI 0.36-0.77, P < 0.001 and r = 0.45, 95% CI 0.17-0.67, P = 0.003, n = 41, respectively). Conclusion Continuous positive airway pressure withdrawal is associated with the prolongation of the QTc and TpTec intervals and TpTe/QT ratio, which may provide a possible mechanistic link between OSA, cardiac dysrhythmias, and thus sudden cardiac deat

Parametric Waveform Synthesis: a scalable approach to generate sub-cycle optical transients

The availability of electromagnetic pulses with controllable field waveform and extremely short duration, even below a single optical cycle, is imperative to fully harness strong-field processes and to gain insight into ultrafast light-driven mechanisms occurring in the attosecond time-domain. The recently demonstrated parametric waveform synthesis (PWS) introduces an energy-, power- and spectrum-scalable method to generate non-sinusoidal sub-cycle optical waveforms by coherently combining different phase-stable pulses attained via optical parametric amplifiers. Significant technological developments have been addressed to overcome the stability issues related to PWS and to obtain an effective and reliable waveform control system. Here we present the main ingredients enabling PWS technology. The design choices concerning the optical, mechanical and electronic setups are justified by analytical/numerical modeling and benchmarked by experimental observations. In its present incarnation, the PWS technology enables the generation of field-controllable mJ-level few-femtosecond pulses spanning the visible to infrared range.Comment: 34 page

COULD JC VIRUS PROVOKE METASTASIS IN COLON CANCER?

AIM: to evaluate the prevalence of John Cunningham Virus (JC virus) in a small cohort of patients with colon cancer and to assess its presence in hepatic metastasis.METHOD: Neneteen consecutive patients with histologically diagnosed colon cancer were included in our study, together with ten subjects affected by histologically and serologically diagnosed hepatitis C virus infection. in the patients included in the colon cancer group, JC virus was searched for the surgical specimen; in the control group, JC virus was searched in the hepatic biopsy. The difference in the prevalence of JC virus in the hepatic biopsy between the two groups was assessed through the X2 test. RESULTS: Four of 19 patients with colon cancer had a positive polymerase chain reaction (PCR) test for JC virus, and four had liver metastasis. Among the patients with liver metastasis, three out four had a positive PCR test for JC virus in the surgical specimen and in the liver biopsy; the only patient with liver metastasis with a negative test for JC virus also presenrted a negative test for JC virus in the surgical specimen. in the control group of patients with hepatitis C infection, none of the ten patients presented JC virus infection in the hepatic biopsy. The difference between the two groups regarding JC virus infection was statistically significant (X2=9.55, P=0,002)

Cost of noninfectious comorbidities in patients with HIV

OBJECTIVES: We hypothesized that the increased prevalence of noninfectious comorbidities (NICMs) observed among HIV-infected patients may result in increased direct costs of medical care compared to the general population. Our objective was to provide estimates of and describe factors contributing to direct costs for medical care among HIV-infected patients, focusing on NICM care expenditure. METHODS: A case-control study analyzing direct medical care costs in 2009. Antiretroviral therapy (ART)-experienced HIV-infected patients (cases) were compared to age, sex, and race-matched adults from the general population, included in the CINECA ARNO database (controls). NICMs evaluated included cardiovascular disease, hypertension, diabetes mellitus, bone fractures, and renal failure. Medical care cost information evaluated included pharmacy, outpatient, and inpatient hospital expenditures. Linear regression models were constructed to evaluate predictors of total care cost for the controls and cases. RESULTS: There were 2854 cases and 8562 controls. Mean age was 46 years and 37% were women. We analyzed data from 29,275 drug prescription records. Positive predictors of health care cost in the overall population: HIV infection (β = 2878; confidence interval (CI) = 2001-3755); polypathology (β = 8911; CI = 8356-9466); age (β = 62; CI = 45-79); and ART exposure (β = 18,773; CI = 17,873-19,672). Predictors of health care cost among cases: Center for Disease Control group C (β = 1548; CI = 330-2766); polypathology (β = 11,081; CI = 9447-12,716); age < 50 years (β = 1903; CI = 542-3264); protease inhibitor exposure (per month of use; β = 69; CI = 53-85); CD4 count < 200 cells/mm3 (β = 5438; CI = 3082-7795); and ART drug change (per change; β = 911; CI = 716-1106). CONCLUSION: Total cost of medical care is higher in cases than controls. Lower medical costs associated with higher CD4 strata are offset by increases in the care costs needed for advancing age, particularly for NICMs

Phosgene formation via carbon monoxide and dichlorine reaction over an activated carbon catalyst: reaction testing arrangements

An apparatus is described to investigate the synthesis of phosgene from the reaction of carbon monoxide and dichlorine over an activated carbon catalyst. Infrared spectroscopy and UV-visible absorption spectroscopy are used to identify and quantify reagents and products. The reaction is operated with an excess of CO in order to enable complete chlorine conversion at elevated temperatures. The reaction profile is examined over the temperature range of 300-445 K, with a phosgene selectivity of 100% observed at all temperatures. An isosbestic point in the UV-visible spectrum is observed at 272 nm, indicating that the dichlorine and the phosgene are in equilibrium. Examination of the phosgene formation rate as a function of space time and catalyst size fraction at 323 K establishes that, under the described conditions, the reaction is operating under chemical control in the absence of mass transfer restrictions