Remarks on Characterizations of Malinowska and Szynal

The problem of characterizing a distribution is an important problem which has recently attracted the attention of many researchers. Thus, various characterizations have been established in many different directions. An investigator will be vitally interested to know if their model fits the requirements of a particular distribution. To this end, one will depend on the characterizations of this distribution which provide conditions under which the underlying distribution is indeed that particular distribution. In this work, several characterizations of Malinowska and Szynal (2008) for certain general classes of distributions are revisited and simpler proofs of them are presented. These characterizations are not based on conditional expectation of the kth lower record values (as in Malinowska and Szynal), they are based on: (i) simple truncated moments of the random variable, (ii) hazard function

The prognostic effect of PTEN expression status in colorectal cancer development and evaluation of factors affecting it: MiR-21 and promoter methylation

Background: PTEN is a tumor suppressor gene which is involved in cellular proliferation, differentiation, and apoptosis. Loss or down-regulation of PTEN plays an important role in human cancers development. In this study, we investigated the effect of miR-21 and promoter methylation on the PTEN expression status in CRC tissues and analyzed association of the PTEN expression status with clinicopathological features in patients with CRC. Results: The PTEN expression was positively detected in 67.2 CRC tissues and all adjacent non-cancerous samples. PTEN mRNA level was negatively correlated with miR-21 level (r = -0.595, P < 0.001). PTEN expression was also correlated directly with the PTEN mRNA level (r = 0.583, P < 0.001) and conversely with miR-21 level (r = -0.632, P < 0.001). PTEN Promoter methylation was significantly associated with PTEN expression status (p = 0.013). PTEN expression was negatively associated with tumor size (p = 0.007) and advanced tumor stage (P = 0.011). Multivariate analysis indicated that tumor stage, tumor differentiation and PTEN expression status were independent prognostic factors for overall carcinoma in CRC patients (P < 0.05). The Kaplan-Meier curve indicated a negative correlation between PTEN expression levels and survival of CRC patients (P = 0.013). Conclusions: This study suggests a high frequency of miR-21 overexpression and aberrant promoter methylation in down-regulation of PTEN expression in colorectal carcinoma. Loss of PTEN may be a prognostic factor for patients with CRC. © 2016 Yazdani et al

Imaging Anyons with Scanning Tunneling Microscopy

Anyons are exotic quasiparticles with fractional charge that can emerge as fundamental excitations of strongly interacting topological quantum phases of matter. Unlike ordinary fermions and bosons, they may obey non-Abelian statistics—a property that would help realize fault-tolerant quantum computation. Non-Abelian anyons have long been predicted to occur in the fractional quantum Hall (FQH) phases that form in two-dimensional electron gases in the presence of a large magnetic field, such as the ν=5/2 FQH state. However, direct experimental evidence of anyons and tests that can distinguish between Abelian and non-Abelian quantum ground states with such excitations have remained elusive. Here, we propose a new experimental approach to directly visualize the structure of interacting electronic states of FQH states with the STM. Our theoretical calculations show how spectroscopy mapping with the STM near individual impurity defects can be used to image fractional statistics in FQH states, identifying unique signatures in such measurements that can distinguish different proposed ground states. The presence of locally trapped anyons should leave distinct signatures in STM spectroscopic maps, and enables a new approach to directly detect—and perhaps ultimately manipulate—these exotic quasiparticles

Impurity induced resonant state in a pseudogap state of a high temperature superconductor

We predict a resonance impurity state generated by the substitution of one Cu atom with a nonmagnetic atom, such as Zn, in the pseudogap state of a high-T_c superconductor. The precise microscopic origin of the pseudogap is not important for this state to be formed, in particular this resonance will be present even in the absence of superconducting fluctuations in the normal state. In the presence of superconducting fluctuations, we predict the existence of a counterpart impurity peak on a symmetric bias. The nature of impurity resonance is similar to the previously studied resonance in the d-wave superconducting state.Comment: 4 pages, 2 figure

Description and Comparison of the Results of the Proposed House: Habitat for Humanity at Frazier Court, Dallas, Texas, with the 2004 IECC Standard Reference House

The Energy Systems Laboratory was requested to calculate the emissions reductions associated with the Habitat for Humanity Housing Project at Frazier Court, Dallas Texas. This report presents the results of the required analysis, a set of houses was compared to a corresponding standard reference house as described in the 2004 International Energy Conservation Code (2004 IECC). The energy consumption calculations were carried out using DOE-2.1e input file RES3ST.inp (Version 4.01.07) and DDP (Version: 1.7.03). Based on this comparison, the % above/below code for the proposed house was determined. The resultant emissions calculations were carried out using eCALC software (ESL, 2006). This report also contains detailed information about the description of the proposed house in terms of its building parameters, resultant energy consumption and emission reductions. Calculations are carried out using TMY2 weather file for Tarrant County, TX which is in climate zone 3 of the IECC 2004 climate zone categories. For the 1285 sq. ft. houses, the energy consumption of the Habitat for Humanity houses is in the range of 10.3% - 11.7% above code and for the 843 sq. ft. houses, the energy consumption is in the range of 20.9% - 21.4% below code. The HERS ratings calculated by IC3 is in the range of 71.7– 74.2 for the 1285 sq. ft. houses and in the range of 79.4 – 80.6 for the 843 sq. ft. houses

Inherent Inhomogeneities in Tunneling Spectra of BSCCO Crystals in the Superconducting State

Scanning Tunneling Spectroscopy on cleaved BSCCO(2212) single crystals reveal inhomogeneities on length-scales of $\sim$30 $\AA$. While most of the surface yields spectra consistent with a d-wave superconductor, small regions show a doubly gapped structure with both gaps lacking coherence peaks and the larger gap having a size typical of the respective pseudo-gap for the same sample.Comment: 4 pages, 4 figure

Electronic Origin of the Inhomogeneous Pairing Interaction in the High-Tc Superconductor Bi2Sr2CaCu2O8+d

Identifying the mechanism of superconductivity in the high-temperature cuprate superconductors is one of the major outstanding problems in physics. We report local measurements of the onset of superconducting pairing in the high-transition temperature (Tc) superconductor Bi2Sr2CaCu2O8+d using a lattice-tracking spectroscopy technique with a scanning tunneling microscope. We can determine the temperature dependence of the pairing energy gaps, the electronic excitations in the absence of pairing, and the effect of the local coupling of electrons to bosonic excitations. Our measurements reveal that the strength of pairing is determined by the unusual electronic excitations of the normal state, suggesting that strong electron-electron interactions rather than low-energy (<0.1 volts) electron-boson interactions are responsible for superconductivity in the cuprates

A trapped single ion inside a Bose-Einstein condensate

Improved control of the motional and internal quantum states of ultracold neutral atoms and ions has opened intriguing possibilities for quantum simulation and quantum computation. Many-body effects have been explored with hundreds of thousands of quantum-degenerate neutral atoms and coherent light-matter interfaces have been built. Systems of single or a few trapped ions have been used to demonstrate universal quantum computing algorithms and to detect variations of fundamental constants in precision atomic clocks. Until now, atomic quantum gases and single trapped ions have been treated separately in experiments. Here we investigate whether they can be advantageously combined into one hybrid system, by exploring the immersion of a single trapped ion into a Bose-Einstein condensate of neutral atoms. We demonstrate independent control over the two components within the hybrid system, study the fundamental interaction processes and observe sympathetic cooling of the single ion by the condensate. Our experiment calls for further research into the possibility of using this technique for the continuous cooling of quantum computers. We also anticipate that it will lead to explorations of entanglement in hybrid quantum systems and to fundamental studies of the decoherence of a single, locally controlled impurity particle coupled to a quantum environment

Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor

Alkali-doped iron selenide is the latest member of high Tc superconductor family, and its peculiar characters have immediately attracted extensive attention. We prepared high-quality potassium-doped iron selenide (KxFe2-ySe2) thin films by molecular beam epitaxy and unambiguously demonstrated the existence of phase separation, which is currently under debate, in this material using scanning tunneling microscopy and spectroscopy. The stoichiometric superconducting phase KFe2Se2 contains no iron vacancies, while the insulating phase has a \surd5\times\surd5 vacancy order. The iron vacancies are shown always destructive to superconductivity in KFe2Se2. Our study on the subgap bound states induced by the iron vacancies further reveals a magnetically-related bipartite order in the superconducting phase. These findings not only solve the existing controversies in the atomic and electronic structures in KxFe2-ySe2, but also provide valuable information on understanding the superconductivity and its interplay with magnetism in iron-based superconductors

Probing d-wave pairing correlations in the pseudogap regime of the cuprate superconductors via low-energy states near impurities

The issue of probing the pseudogap regime of the cuprate superconductors, specifically with regard to the existence and nature of superconducting pairing correlations of d-wave symmetry, is explored theoretically. It is shown that if the d-wave correlations believed to describe the superconducting state persist into the pseudogap regime, but with pair-potential phase-fluctuations that destroy their long-range nature, then the low-energy quasiparticle states observed near extended impurities in the truly superconducting state should also persist as resonances in the pseudogap regime. The scattering of quasiparticles by these phase-fluctuations broadens what was (in the superconducting state) a sharp peak in the single-particle spectral function at low energy, as we demonstrate within the context of a simple model. This peak and its broadening is, in principle, accessible via scanning tunneling spectroscopy near extended impurities in the pseudogap regime. If so, such experiments would provide a probe of the extent to which d-wave superconducting correlations persist upon entering the pseudogap regime, thus providing a stringent diagnostic of the phase-fluctuation scenario.Comment: 8 pages, 2 figure