2,395 research outputs found
Teleporting the one-qubit state via two-level atoms with spontaneous emission
We study quantum teleportation via two two-level atoms coupled collectively
to a multimode vacuum field and prepared initially in different atomic states.
We concentrated on influence of the spontaneous emission, collective damping
and dipole-dipole interaction of the atoms on fidelity dynamics of quantum
teleportation and obtained the region of spatial distance between the two atoms
over which the state can be teleported nonclassically. Moreover, we showed
through concrete examples that entanglement of the channel state is the
prerequisite but not the only essential quantity for predicting the
teleportation fidelity.Comment: 14 pages, 6 figure
Antireflection silicon structures with hydrophobic property fabricated by three-beam laser interference
This paper demonstrates antireflective structures on silicon wafer surfaces with hydrophobic property fabricated by three-beam laser interference. In this work, a three-beam laser interference system was set up to generate periodic micro-nano hole structures with hexagonal distributions. Compared with the existing technologies, the array of hexagonally-distributed hole structures fabricated by three-beam laser interference reveals a design guideline to achieve considerably low solar-weighted reflectance (SWR) in the wavelength range of 300-780 nm. The resulting periodic hexagonally-distributed hole structures have shown extremely low SWR (1.86%) and relatively large contact angle (140°) providing with a self-cleaning capability on the solar cell surface
Intersite coupling effects in a Kondo lattice
The La dilution of the Kondo lattice CeCoIn_5 is studied. The scaling laws
found for the magnetic susceptibility and the specific heat reveal two
well-separated energy scales, corresponding to the single impurity Kondo
temperature T_K and an intersite spin-liquid temperature T^*. The Ce-dilute
alloy has the expected Fermi liquid ground state, while the specific heat and
resistivity in the dense Kondo regime exhibit non-Fermi-liquid behavior, which
scales with T^*. These observations indicate that the screening of the magnetic
moments in the lattice involves antiferromagnetic intersite correlations with a
larger energy scale in comparison with the Kondo impurity case.Comment: 4 pages, 4 figure
First order transition from correlated electron semiconductor to ferromagnetic metal in single crystalline FeSi1-xGex
The phase diagram of FeSi1-xGex, obtained from magnetic, thermal and
transport measurements on single crystals, shows a first-order transition from
a correlated electron semiconductor to a ferromagnetic metal at a critical
concentration, x ~ 0.25. The gap of the insulating phase strongly decreases
with x. The specific heat coefficient appears to track the density of states of
a Kondo insulator. The phase diagram is consistent with a correlation induced
insulator-metal transition in conjunction with disorder on the Si/Ge ligand
site
Diet-induced gene expression of isolated pancreatic islets from a polygenic mouse model of the metabolic syndrome
AIMS/HYPOTHESIS: Numerous new genes have recently been identified in genome-wide association studies for type 2 diabetes. Most are highly expressed in beta cells and presumably play important roles in their function. However, these genes account for only a small proportion of total risk and there are likely to be additional candidate genes not detected by current methodology. We therefore investigated islets from the polygenic New Zealand mouse (NZL) model of diet-induced beta cell dysfunction to identify novel genes and pathways that may play a role in the pathogenesis of diabetes. METHODS: NZL mice were fed a diabetogenic high-fat diet (HF) or a diabetes-protective carbohydrate-free HF diet (CHF). Pancreatic islets were isolated by laser capture microdissection (LCM) and subjected to genome-wide transcriptome analyses. RESULTS: In the prediabetic state, 2,109 islet transcripts were differentially regulated (>1.5-fold) between HF and CHF diets. Of the genes identified, 39 (e.g. Cacna1d, Chd2, Clip2, Igf2bp2, Dach1, Tspan8) correlated with data from the Diabetes Genetics Initiative and Wellcome Trust Case Control Consortium genome-wide scans for type 2 diabetes, thus validating our approach. HF diet induced early changes in gene expression associated with increased cell-cycle progression, proliferation and differentiation of islet cells, and oxidative stress (e.g. Cdkn1b, Tmem27, Pax6, Cat, Prdx4 and Txnip). In addition, pathway analysis identified oxidative phosphorylation as the predominant gene-set that was significantly upregulated in response to the diabetogenic HF diet. CONCLUSIONS/INTERPRETATION: We demonstrated that LCM of pancreatic islet cells in combination with transcriptional profiling can be successfully used to identify novel candidate genes for diabetes. Our data strongly implicate glucose-induced oxidative stress in disease progression
Is there a Phase Transition to the Flux Lattice State?
The sharp drops in the resistance and magnetization which are usually
attributed to a phase transition from the vortex liquid state to a crystal
state are explained instead as a crossover between three and two dimensional
behavior, which occurs when the phase coherence length in the liquid becomes
comparable to the sample thickness. Estimates of the width of the crossover
region and the phase coherence length scales are in agreement with experiment.Comment: 4 pages, RevTe
Flux-lattice melting in two-dimensional disordered superconductors
The flux line lattice melting transition in two-dimensional pure and
disordered superconductors is studied by a Monte Carlo simulation using the
lowest Landau level approximation and quasi-periodic boundary condition on a
plane. The position of the melting line was determined from the diffraction
pattern of the superconducting order parameter. In the clean case we confirmed
the results from earlier studies which show the existence of a quasi-long range
ordered vortex lattice at low temperatures. Adding frozen disorder to the
system the melting transition line is shifted to slightly lower fields. The
correlations of the order parameter for translational long range order of the
vortex positions seem to decay slightly faster than a power law (in agreement
with the theory of Carpentier and Le Doussal) although a simple power law decay
cannot be excluded. The corresponding positional glass correlation function
decays as a power law establishing the existence of a quasi-long range ordered
positional glass formed by the vortices. The correlation function
characterizing a phase coherent vortex glass decays however exponentially
ruling out the possible existence of a phase coherent vortex glass phase.Comment: 12 pages, 21 figures, final version to appear in Phys. Rev.
The effects of multiple features of alternatively spliced exons on the K(A)/K(S )ratio test
BACKGROUND: The evolution of alternatively spliced exons (ASEs) is of primary interest because these exons are suggested to be a major source of functional diversity of proteins. Many exon features have been suggested to affect the evolution of ASEs. However, previous studies have relied on the K(A)/K(S )ratio test without taking into consideration information sufficiency (i.e., exon length > 75 bp, cross-species divergence > 5%) of the studied exons, leading to potentially biased interpretations. Furthermore, which exon feature dominates the results of the K(A)/K(S )ratio test and whether multiple exon features have additive effects have remained unexplored. RESULTS: In this study, we collect two different datasets for analysis – the ASE dataset (which includes lineage-specific ASEs and conserved ASEs) and the ACE dataset (which includes only conserved ASEs). We first show that information sufficiency can significantly affect the interpretation of relationship between exons features and the K(A)/K(S )ratio test results. After discarding exons with insufficient information, we use a Boolean method to analyze the relationship between test results and four exon features (namely length, protein domain overlapping, inclusion level, and exonic splicing enhancer (ESE) frequency) for the ASE dataset. We demonstrate that length and protein domain overlapping are dominant factors, and they have similar impacts on test results of ASEs. In addition, despite the weak impacts of inclusion level and ESE motif frequency when considered individually, combination of these two factors still have minor additive effects on test results. However, the ACE dataset shows a slightly different result in that inclusion level has a marginally significant effect on test results. Lineage-specific ASEs may have contributed to the difference. Overall, in both ASEs and ACEs, protein domain overlapping is the most dominant exon feature while ESE frequency is the weakest one in affecting test results. CONCLUSION: The proposed method can easily find additive effects of individual or multiple factors on the K(A)/K(S )ratio test results of exons. Therefore, the system can analyze complex conditions in evolution where multiple features are involved. More factors can also be added into the system to extend the scope of evolutionary analysis of exons. In addition, our method may be useful when orthologous exons can not be found for the K(A)/K(S )ratio test
Clinical significance of VEGF-A, -C and -D expression in esophageal malignancies
Vascular endothelial growth factors ( VEGF)- A, - C and - D are members of the proangiogenic VEGF family of glycoproteins. VEGF-A is known to be the most important angiogenic factor under physiological and pathological conditions, while VEGF-C and VEGF-D are implicated in the development and sprouting of lymphatic vessels, so called lymphangiogenesis. Local tumor progression, lymph node metastases and hematogenous tumor spread are important prognostic factors for esophageal carcinoma ( EC), one of the most lethal malignancies throughout the world. We found solid evidence in the literature that VEGF expression contributes to tumor angiogenesis, tumor progression and lymph node metastasis in esophageal squamous cell carcinoma ( SCC), and many authors could show a prognostic value for VEGF-assessment. In adenocarcinoma (AC) of the esophagus angiogenic properties are acquired in early stages, particularly in precancerous lesions like Barrett's dysplasia. However, VEGF expression fails to give prognostic information in AC of the esophagus. VEGF-C and VEGF-D were detected in SCC and dysplastic lesions, but not in normal mucosa of the esophagus. VEGF-C expression might be associated with lymphatic tumor invasion, lymph node metastases and advanced disease in esophageal SCC and AC. Therapeutic interference with VEGF signaling may prove to be a promising way of anti-angiogenic co-treatment in esophageal carcinoma. However, concrete clinical data are still pending
COVID-19 Related Mobility Reduction: Heterogenous Effects on Sleep and Physical Activity Rhythms
Mobility restrictions imposed to suppress coronavirus transmission can alter
physical activity (PA) and sleep patterns. Characterization of response
heterogeneity and their underlying reasons may assist in tailoring customized
interventions. We obtained wearable data covering baseline, incremental
movement restriction and lockdown periods from 1824 city-dwelling, working
adults aged 21 to 40 years, incorporating 206,381 nights of sleep and 334,038
days of PA. Four distinct rest activity rhythms (RARs) were identified using
k-means clustering of participants' temporally distributed step counts.
Hierarchical clustering of the proportion of time spent in each of these RAR
revealed 4 groups who expressed different mixtures of RAR profiles before and
during the lockdown. Substantial but asymmetric delays in bedtime and waketime
resulted in a 24 min increase in weekday sleep duration with no loss in sleep
efficiency. Resting heart rate declined 2 bpm. PA dropped an average of 38%. 4
groups with different compositions of RAR profiles were found. Three were
better able to maintain PA and weekday/weekend differentiation during lockdown.
The least active group comprising 51 percent of the sample, were younger and
predominantly singles. Habitually less active already, this group showed the
greatest reduction in PA during lockdown with little weekday/weekend
differences. Among different mobility restrictions, removal of habitual social
cues by lockdown had the largest effect on PA and sleep. Sleep and resting
heart rate unexpectedly improved. RAR evaluation uncovered heterogeneity of
responses to lockdown and can identify characteristics of persons at risk of
decline in health and wellbeing.Comment: 30 pages, 3 main figures, 3 tables, 4 supplementary figure
- …