Photonic generation of impulse ultrawideband signals with switchable shapes and polarities based on frequency-to-time mapping

A photonic approach to generate impulse ultrawideband (UWB) signals with switchable shapes and polarities based on the frequency-to-time mapping technique is proposed and demonstrated. UWB monocycle, doublet, and triplet signals with two polarities can be obtained by adjusting the switchable spectrum shaper.

PDM RZ-to-NRZ and NRZ-to-PRZ format conversions using a variable DGD element inside a polarization-diversified loop

A novel scheme for bit-rate-variable polarization-division-multiplexed return-to-zero to nonreturn-to-zero and NRZ to pseudo-return-to-zero format conversions is proposed using a variable differential-group-delay element inside a polarization-diversified loop. Conversion for both 2×10 and 2×12.5 Gbit/s PDM signals are successfully demonstrated with approximately 1 dB additional power penalty by properly adjusting DGD values of the variable DGD element.

Spin transition in the ν=8/3 fractional quantum Hall effect

We present here the results from a density dependent study of the activation energy gaps of the fractional quantum Hall effect states at Landau level fillings ν=8/3 and 7/3 in a series of high quality quantum wells. In the density range from 0.5×10(11) to 3×10(11) cm(-2), the 7/3 energy gap increases monotonically with increasing density, supporting its ground state being spin polarized. For the 8/3 state, however, its energy gap first decreases with increasing density, almost vanishes at n~0.8×10(11) cm(-2), and then turns around and increases with increasing density, clearly demonstrating a spin transition.

Simultaneous all-optical RZ-to-NRZ format conversion for two tributaries in PDM signal using a single section of highly nonlinear fiber

Simultaneous all-optical RZ-OOK to NRZ-OOK format conversion for two tributaries in PDM signal is demonstrated utilizing a single section of highly nonlinear fiber through polarization nonlinear loop mirror configuration. Less than 1-dB power penalty is achieved in a 2 × 12.5-Gb/s PDM system, and only 1.4-dB SNR penalty is obtained in a 2 × 40-Gb/s PDM system.

Reversible watermarking based on invariant image classification and dynamical error histogram shifting

In this article, we present a novel reversible watermarking scheme. Its originality stands in identifying parts of the image that can be watermarked additively with the most adapted lossless modulation between: Pixel Histogram Shifting (PHS) or Dynamical Error Histogram Shifting (DEHS). This classification process makes use of a reference image derived from the image itself, a prediction of it, which has the property to be invariant to the watermark addition. In that way, watermark embedded and reader remain synchronized through this image of reference. DEHS is also an original contribution of this work. It shifts predict-errors between the image and its reference image taking care of the local specificities of the image, thus dynamically. Conducted experiments, on different medical image test sets issued from different modalities and some natural images, show that our method can insert more data with lower distortion than the most recent and efficient methods of the literature.

Secondary preventive medication persistence and adherence 1 year after stroke

OBJECTIVE

Data on long-term use of secondary prevention medications following stroke are limited. The Adherence eValuation After Ischemic stroke-Longitudinal (AVAIL) Registry assessed patient, provider, and system-level factors influencing continuation of prevention medications for 1 year following stroke hospitalization discharge.

METHODS

Patients with ischemic stroke or TIA discharged from 106 hospitals participating in the American Heart Association Get With The Guidelines-Stroke program were surveyed to determine their use of warfarin, antiplatelet, antihypertensive, lipid-lowering, and diabetes medications from discharge to 12 months. Reasons for stopping medications were ascertained. Persistence was defined as continuation of all secondary preventive medications prescribed at hospital discharge, and adherence as continuation of prescribed medications except those stopped according to health care provider instructions.

RESULTS

Of the 2,880 patients enrolled in AVAIL, 88.4% (2,457 patients) completed 1-year interviews. Of these, 65.9% were regimen persistent and 86.6% were regimen adherent. Independent predictors of 1-year medication persistence included fewer medications prescribed at discharge, having an adequate income, having an appointment with a primary care provider, and greater understanding of why medications were prescribed and their side effects. Independent predictors of adherence were similar to those for persistence.

CONCLUSIONS

Although up to one-third of stroke patients discontinued one or more secondary prevention medications within 1 year of hospital discharge, self-discontinuation of these medications is uncommon. Several potentially modifiable patient, provider, and system-level factors associated with persistence and adherence may be targets for future interventions.

Termination of two-dimensional metallic conduction near the metal-insulator transition in a Si/SiGe quantum well

We report in this Letter our recent low-temperature transport results in a Si/SiGe quantum well with moderate peak mobility. An apparent metal-insulating transition is observed. Within a small range of densities near the transition, the conductivity σ displays a nonmonotonic temperature dependence. After an initial decrease at high temperatures, σ first increases with decreasing temperature T, showing a metallic behavior. As T continues decreasing, a downturn in σ is observed. This downturn shifts to a lower T at higher densities. More interestingly, the downturn temperature shows a power-law dependence on the mobility at the downturn position, suggesting that a similar downturn is also expected to occur deep in the apparent metallic regime at albeit experimentally inaccessible temperatures. This thus hints that the observed metallic phase in 2D systems might be a finite temperature effect.

The role of acculturation in diabetes self-management among Chinese Americans with type 2 diabetes

AIMS

We sought to examine the acculturation level and its relationship with diabetes self-management among Chinese Americans with type 2 diabetes.

METHODS

We conducted a cross-sectional survey research study in a convenience sample of 211 Chinese Americans with type 2 diabetes. We measured acculturation and diabetes self-management and evaluated the association between acculturation and self-management behaviors after controlling participants' characteristics using structural equation modeling.

RESULTS

The majority of the participants was born outside the U.S. and had a low level of acculturation. Women and older individuals were less acculturated, and those who had higher social economic status and lived in the U.S. for a longer period were more acculturated. The results of the structural equation modeling demonstrated that acculturation was significantly associated with DM self-management, and more-acculturated individuals were more likely to perform DM self-management than less-acculturated ones after controlling demographic characteristics.

CONCLUSIONS

The results of this study indicated that Chinese Americans diagnosed with diabetes may benefit from acculturation to mainstream society probably because increased acculturation was associated with increased help seeking behaviors and increased use of professional services.

Comb filter with independently tunable wavelength spacing and bandwidth using cascaded variable differential group delay elements

An all-optical comb filter with independently tunable wavelength spacing and bandwidth (BW) is proposed. Using three cascaded variable differential-group-delay elements, we demonstrate theoretically and experimentally the tunability of the comb filter with >10 dB sidelobe reduction by adjusting three elements. The wavelength spacing is determined by the first filter module, while the sidelobe suppression ratio and the BW are defined by the middle and the last one, respectively.

Impact of disorder on the 5/2 fractional quantum Hall state

We compare the energy gap of the ν = 5/2 fractional quantum Hall effect state obtained in conventional high mobility modulation-doped quantum-well samples with those obtained in high quality GaAs transistors (heterojunction insulated gate field-effect transistors). We are able to identify the different roles that long-range and short-range disorders play in the 5/2 state and observe that the long-range potential fluctuations are more detrimental to the strength of the 5/2 state than short-range potential disorder.

Quantum Hall ferromagnetism in the presence of tunable disorder

In this Letter, we report our recent experimental results on the energy gap of the ν=1 quantum Hall state (Δ(ν=1)) in a quantum antidot array sample, where the effective disorder potential can be tuned continuously. Δ(ν=1) is nearly constant at small effective disorders, and collapses at a critical disorder. Moreover, in the weak disorder regime, Δ(ν=1) shows a B(total)(1/2) dependence in tilted magnetic field measurements, while in the strong disorder regime, Δ(ν=1) is linear in B(total), where B(total) is the total magnetic field at ν=1. We discuss our results within several models involving the quantum Hall ferromagnetic ground state and its interplay with sample disorder.

Proteome analysis of differential protein expression in brain of rats with type 1 diabetes mellitus

AIM OF THE STUDY

Proteomic approach was applied to identify differential protein expressed in brain of rats with type 1 diabetes mellitus (T1DM) in order to search for potential biomarkers for pathological changes of brain with T1DM.

METHODS

Proteins were extracted from brain tissues of T1DM rats and healthy control rats, separated by 2-DE and identified by MALDI-TOF-MS. The results were validated by Western blot analysis and immunohistochemistry (IHC).

RESULTS

A total of 8 proteins from the 24 differentially expressed spots were identified by MALDI-TOF-MS. The proteins identified were vitamin D-dependent calcium-binding protein, creatine kinase B-type (B-CK), myosin light chain kinase (MLCK), HSP60 and HSP71, ATP synthase, cyclin-G, pantothenate kinase-1 (PANK1), respectively. 3 proteins were up-regulated and 5 proteins were down-regulated from the T1DM rats. Of the 8 proteins identified, MLCK was confirmed by Western blot and IHC.

CONCLUSION

This work demonstrates that a comprehensive strategy of proteomic identification should be a useful tool for understanding of diabetic encephalopathy mechanism. And the differential proteins such as MLCK may be give clues about the pathogenesis of diabetic encephalopathy.

Dry Etching Issues in the Integration of Ferroelectric Thin Film Capacitors

Dry etching is an area that demands a great deal of attention in the large scale integration of ferroelectric thin film capacitors for nonvolatile random access memory applications. In this review, we discuss some of the issues relating to the etching of the ferroelectric films, patterning of the electrodes, device damage caused by the etch process and post-etch residue problems. An etch process that can provide high etch rates and good etch anisotropy for the current candidate ferroelectrics including Pb(Zr, Ti)O3 and layered structure SrBi2Ta2O9 thin films using environmentally benign gases such as hydrochlorofluorocarbons is presented. The etch mechanism for both of these materials was determined to rely substantially on ion bombardment effects. For example, PZT films were etched anisotropically at rates of up to 60 nm/min using CHCIFCF3 gas under high rf power and low gas pressure conditions. Problems remain with respect to the acrosswafer differential etch rates observed when more than one phase is present in the material (e.g., amorphous/pyrochlore + perovskite phases in PZT). Damage caused by the etch process which can lead to changes in device characteristics, including hysteresis and fatigue properties, and the underlying mechanism that causes the damage are discussed. O2 was found to be a suitable etch gas for etching the conductive oxide electrode material RuO2. However, an anomaly in the etch rate was detected upon introduction of a small amount of fluorine containing gas: addition of 2% of CF3CFH2 gas to the O2 plasma increases the etch rate by a factor of four. This can be taken advantage of in obtaining high etch selectivity between the electrode and ferroelectric layers.

Let-7/miR-98 regulate Fas and Fas-mediated apoptosis

Fas is ubiquitously expressed on a variety of cells and triggers apoptosis, which have critical roles in the immune system. MicroRNAs (miRNAs) have been recently identified as regulators that modulate target gene expression and are involved in diverse biological processes, such as cell proliferation and apoptosis. This study was undertaken to investigate the contribution of miRNA in the regulation of Fas expression and Fas-mediated apoptosis. Bioinformatics analysis indicated that Fas was a potential target of let-7/miR-98 family. Indeed ectopic expression of let-7/miR-98 reduced, whereas knockdown of endogenous let-7/miR-98 increased the expression of Fas at both mRNA and protein levels. Let-7/miR-98 was verified to target Fas 3' untranslated region directly by site-directed gene mutagenesis and reporter gene assay. More importantly, introduction of let-7/miR-98 could decrease the sensitivity to Fas-induced apoptosis. Furthermore, let-7/miR-98 expression was reduced in activation-induced cell death process, accompanied by increased expression of Fas. In conclusion, our study first demonstrated that let-7/miR-98 regulated Fas expression and the sensitivity of Fas-mediated apoptosis.

Differential endothelial cell gene expression by African Americans versus Caucasian Americans: a possible contribution to health disparity in vascular disease and cancer

BACKGROUND

Health disparities and the high prevalence of cardiovascular disease continue to be perplexing worldwide health challenges. This study addresses the possibility that genetic differences affecting the biology of the vascular endothelium could be a factor contributing to the increased burden of cardiovascular disease and cancer among African Americans (AA) compared to Caucasian Americans (CA).

METHODS

From self-identified, healthy, 20 to 29-year-old AA (n = 21) and CA (n = 17), we established cultures of blood outgrowth endothelial cells (BOEC) and applied microarray profiling. BOEC have never been exposed to in vivo influences, and their gene expression reflects culture conditions (meticulously controlled) and donor genetics. Significance Analysis of Microarray identified differential expression of single genes. Gene Set Enrichment Analysis examined expression of pre-determined gene sets that survey nine biological systems relevant to endothelial biology.

RESULTS

At the highly stringent threshold of False Discovery Rate (FDR) = 0, 31 single genes were differentially expressed in AA. PSPH exhibited the greatest fold-change (AA > CA), but this was entirely accounted for by a homolog (PSPHL) hidden within the PSPH probe set. Among other significantly different genes were: for AA > CA, SOS1, AMFR, FGFR3; and for AA < CA, ARVCF, BIN3, EIF4B. Many more (221 transcripts for 204 genes) were differentially expressed at the less stringent threshold of FDR <.05. Using the biological systems approach, we identified shear response biology as being significantly different for AA versus CA, showing an apparent tonic increase of expression (AA > CA) for 46/157 genes within that system.

CONCLUSIONS

Many of the genes implicated here have substantial roles in endothelial biology. Shear stress response, a critical regulator of endothelial function and vascular homeostasis, may be different between AA and CA. These results potentially have direct implications for the role of endothelial cells in vascular disease (hypertension, stroke) and cancer (via angiogenesis). Also, they are consistent with our over-arching hypothesis that genetic influences stemming from ancestral continent-of-origin could impact upon endothelial cell biology and thereby contribute to disparity of vascular-related disease burden among AA. The method used here could be productively employed to bridge the gap between information from structural genomics (for example, disease association) and cell function and pathophysiology.

Spatial patterns of pulmonary tuberculosis incidence and their relationship to socio-economic status in Vitoria, Brazil

OBJECTIVE

To investigate spatial patterns of the incidence of pulmonary tuberculosis (TB) and its relationship with socio-economic status in Vitoria, Espirito Santo, Brazil.

DESIGN

In a 4-year, retrospective, territory-based surveillance study of all new pulmonary TB cases conducted in Vitoria between 2002 and 2006, spatial patterns of disease incidence were compared using spatial clustering statistics (Anselin's local indicators of spatial association [LISA] and Getis-Ord Gi* statistics), smoothed empirical Bayes estimates and model-predicted incidence rates. Spatial Poisson models were fit to examine the relationship between socio-economic status and TB incidence.

RESULTS

A total of 651 TB cases were reported across 78 neighborhoods, with rates ranging from 0 to 129 cases per 100,000 population. Moran's I indicated strong spatial autocorrelation among incidence rates (0.399, P < 0.0001), and four areas of high incidence were identified by LISA and Gi* statistics. Smoothed spatial empirical Bayes estimates demonstrate that two of these areas range from 70 to 90 cases/100,000, while the other two range from 40 to 70 cases/100,000. TB incidence and socio-economic status had a significant curvilinear relationship (P = 0.02).

CONCLUSIONS

Data derived from these spatial statistical tools will help TB control programs to allocate TB resources to those populations most at risk of increasing TB rates and to target areas where TB control efforts need to be concentrated.

Simultaneous NRZ-to-RZ format conversion and one-to-six error-free channel multicasting using a single pump in a highly nonlinear fiber

We demonstrate simultaneous 10-Gb/s NRZ-to-RZ format conversion and multicasting from one to many data channels in a highly nonlinear fiber (HNLF) with only a single pump. Functionalities are achieved based on various nonlinear effects, such as four-wave-mixing (FWM), cross-gain-modulation (XGM) and cross-phase-modulation (XPM) between the pump channel and the NRZ data channel. Up to five and six converted data channels are error-free (10(-9) BER) as the wavelength spacing between the pump and the NRZ signal is set to 0.4-nm and 0.8-nm, respectively.