Do TZDs increase the risk of heart failure for patients with diabetes?

Patients with diabetes who take thiazolidinediones (TZDs) have a higher incidence of congestive heart failure (CHF) than those who do not; the incidence of CHF is similar with the use of pioglitazone (Actos), troglitazone (Rezulin), or rosiglitazone (Avandia) (strength of recommendation [SOR]: B, based on a large retrospective cohort study). However, patients on regimens that include pioglitazone but not insulin have lower rates of CHF than those taking insulin but not pioglitazone (SOR: B, based on a retrospective cohort study). Still, patients starting any TZD should be warned of the possibility of CHF and should be monitored for its development. TZDs are contraindicated for patients with class III and IV CHF (SOR: C, based on expert opinion)

4D visualization of embryonic, structural crystallization by single-pulse microscopy

In many physical and biological systems the transition from an amorphous to ordered native structure involves complex energy landscapes, and understanding such transformations requires not only their thermodynamics but also the structural dynamics during the process. Here, we extend our 4D visualization method with electron imaging to include the study of irreversible processes with a single pulse in the same ultrafast electron microscope (UEM) as used before in the single-electron mode for the study of reversible processes. With this augmentation, we report on the transformation of amorphous to crystalline structure with silicon as an example. A single heating pulse was used to initiate crystallization from the amorphous phase while a single packet of electrons imaged selectively in space the transformation as the structure continuously changes with time. From the evolution of crystallinity in real time and the changes in morphology, for nanosecond and femtosecond pulse heating, we describe two types of processes, one that occurs at early time and involves a nondiffusive motion and another that takes place on a longer time scale. Similar mechanisms of two distinct time scales may perhaps be important in biomolecular folding

Hole-hole interaction in a strained Inx_xGa1−x_{1-x}As two dimensional system

The interaction correction to the conductivity of 2D hole gas in strained GaAs/In$_x$Ga$_{1-x}$As/GaAs quantum well structures was studied. It is shown that the Zeeman splitting, spin relaxation and ballistic contribution should be taking into account for reliable determination of the Fermi-liquid constant $F_0^\sigma$. The proper consideration of these effects allows us to describe both th temperature and magnetic field dependences of the conductivity and find the value of $F_0^\sigma$.Comment: 7 pages, 6 figure

Quasiclassical magnetotransport in a random array of antidots

We study theoretically the magnetoresistance $\rho_{xx}(B)$ of a two-dimensional electron gas scattered by a random ensemble of impenetrable discs in the presence of a long-range correlated random potential. We believe that this model describes a high-mobility semiconductor heterostructure with a random array of antidots. We show that the interplay of scattering by the two types of disorder generates new behavior of $\rho_{xx}(B)$ which is absent for only one kind of disorder. We demonstrate that even a weak long-range disorder becomes important with increasing $B$. In particular, although $\rho_{xx}(B)$ vanishes in the limit of large $B$ when only one type of disorder is present, we show that it keeps growing with increasing $B$ in the antidot array in the presence of smooth disorder. The reversal of the behavior of $\rho_{xx}(B)$ is due to a mutual destruction of the quasiclassical localization induced by a strong magnetic field: specifically, the adiabatic localization in the long-range Gaussian disorder is washed out by the scattering on hard discs, whereas the adiabatic drift and related percolation of cyclotron orbits destroys the localization in the dilute system of hard discs. For intermediate magnetic fields in a dilute antidot array, we show the existence of a strong negative magnetoresistance, which leads to a nonmonotonic dependence of $\rho_{xx}(B)$.Comment: 21 pages, 13 figure

Electron-electron interaction at decreasing kFlk_Fl

The contribution of the electron-electron interaction to conductivity is analyzed step by step in gated GaAs/InGaAs/GaAs heterostructures with different starting disorder. We demonstrate that the diffusion theory works down to $k_F l\simeq 1.5-2$, where $k_F$ is the Fermi quasimomentum, $l$ is the mean free paths. It is shown that the e-e interaction gives smaller contribution to the conductivity than the interference independent of the starting disorder and its role rapidly decreases with $k_Fl$ decrease.Comment: 5 pages, 6 figure

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

Quantum interference between one- and two-photon absorption pathways allows coherent control of interband transitions in unbiased bulk semiconductors; carrier population, carrier spin polarization, photocurrent injection, and spin current injection may all be controlled. We extend the theory of these processes to include the electron-hole interaction. Our focus is on photon energies that excite carriers above the band edge, but close enough to it so that transition amplitudes based on low order expansions in $\mathbf{k}$ are applicable; both allowed-allowed and allowed-forbidden two-photon transition amplitudes are included. Analytic solutions are obtained using the effective mass theory of Wannier excitons; degenerate bands are accounted for, but envelope-hole coupling is neglected. We find a Coulomb enhancement of two-color coherent control process, and relate it to the Coulomb enhancements of one- and two-photon absorption. In addition, we find a frequency dependent phase shift in the dependence of photocurrent and spin current on the optical phases. The phase shift decreases monotonically from $\pi /2$ at the band edge to 0 over an energy range governed by the exciton binding energy. It is the difference between the partial wave phase shifts of the electron-hole envelope function reached by one- and two-photon pathways.Comment: 31 pages, 4 figures, to be published in Phys. Rev.

The association between diet quality and mental health during the perinatal period. A systematic review

BACKGROUND: While maternal nutrition during pregnancy is known to play a critical role in the health of both mother and offspring, the magnitude of this association has only recently been realized. Novel, epigenetic data suggest that maternal dietary intake has permanent phenotypic consequences for offspring, highlighting the potency of antenatal diet. To date, the relationship between poor antenatal diet and maternal mental health specifically, remains poorly understood. Therefore, we aimed to systematically review evidence that has examined associations between antenatal diet quality and the experience of depressive, anxiety and stress symptoms during the perinatal period. METHODS: A search for peer-reviewed papers was conducted using Medline Complete, PsycINFO, CINAHL, Academic Search Premiere and Psychology and Behavioral Science Collection. RESULTS: Nine studies (cohort = 4, cross-sectional = 5) published between 2005 and 2013 were eligible for inclusion in this review. A synthesis of findings revealed positive associations between poor quality and unhealthy diets and antenatal depressive and stress symptoms. Healthy diets were inversely associated with antenatal depressive and anxiety symptoms. Postnatal depressive symptoms demonstrated inconsistent results. CONCLUSIONS: Given the paucity of research examining diet quality and mental health in women during the perinatal period, further sufficiently powered studies are urgently required to examine this association

Multiwavelength XMM-Newton observations of the Laor et al. sample of PG quasars

We present XMM-Newton/EPIC spectra for the Laor et al. sample of Palomar Green quasars. We find that a power-law provides a reasonable fit to the 2-5 keV region of the spectra. Excess soft X-ray emission below 2 keV is present for all objects, with the exception of those known to contain a warm absorber. A single power-law is, however, a poor fit to the 0.3-10.0 keV spectrum and instead we find that a simple model, consisting of a broken power-law (plus an iron line), provides a reasonable fit in most cases. The equivalent width of the emission line is constrained in just twelve objects but with low (<2 sigma) significance in most cases. For the sources whose spectra are well-fit by the broken power-law model, we find that various optical and X-ray line and continuum parameters are well-correlated; in particular, the power-law photon index is well-correlated with the FWHM of the Hbeta line and the photon indices of the low and high energy components of the broken power-law are well-correlated with each other. These results suggest that the 0.3-10 keV X-ray emission shares a common (presumably non-thermal) origin, as opposed to suggestions that the soft excess is directly produced by thermal disc emission or via an additional spectral component. We present XMM-Newton/OM data which we combine with the X-ray spectra so as to produce broad-band spectral energy distributions, free from uncertainties due to long-term variability in non-simultaneous data. Fitting these optical-UV spectra with a Comptonized disc model indicates that the soft X-ray excess is independent of the accretion disc, confirming our interpretation of the tight correlation between the hard and soft X-ray spectra.Comment: Accepted for publication in MNRA

Anomalous Low-Field Classical Magnetoresistance in Two Dimensions

The magnetoresistance of classical two-dimensional electrons scattered by randomly distributed impurities is investigated by numerical simulation. At low magnetic fields, we find for the first time a negative magnetoresistance proportional to |B|. This unexpected behavior is shown to be due to a memory effect specific for backscattering events, which was not considered previously.Comment: 4 pages, 4 figure