Quantum tunneling of the interfaces between normal-metal and superconducting regions of a type-I Pb superconductor

Evidence of a non-thermal magnetic relaxation in the intermediate state of a type-I superconducor is presented. It is attributed to quantum tunneling of interfaces separating normal and superconducting regions. Tunneling barriers are estimated and temperature of the crossover from thermal to quantum regime is obtained from Caldeira-Leggett theory. Comparison between theory and experiment points to tunneling of interface segments of size comparable to the coherence length, by steps of order one nanometer

Silver-enriched ZnO:Ag thin films deposited by magnetron co-sputtering: Post annealing effects on structural and physical properties

The ZnO semiconductor is probably among the most mentioned compounds in the scientific literature during the last decade, which is mainly due to its wide spectrum of applications. Compounds based on ZnO (in doped or composite form) are of great relevance for the development of high-tech devices. In this work, we present the growth and characterization of samples deposited by DC Magnetron co-sputtering from two pure Zn and Ag targets in an O2 / Ar atmosphere. The samples were characterized as deposited and after an annealing treatment in a reducing atmosphere. We have used XRD, RBS, ellipsometry, UV visible photoluminescence, and electrical measurements for sample characterization. The results revealed the amorphization of ZnO when the Ag content increases and, after annealing, a mixture of crystalline phases was detected for the samples with higher Ag content. It is also demonstrated the strong effect of the presence of Ag atoms in the stimulated optical and electrical responses from ZnO:Ag compounds obtained in this wor

Size effect and surface tension measurements in Ni and Co nanowires

The effect of reduced size on the mechanical and elastic properties measured on 35 nm diameter Ni and Co nanowires is presented and discussed. The stresses induced in the nanowires due to the different thermal expansion constants of the metal and alumina change the magnetic properties of the nanowires, allowing one to measure the effective Young's modulus and the surface tension of the nanowires by means of simple magnetometry. The Young's modulus of the longer nanowire is higher than that of the shorter one that is comparable to its bulk value. This effect is successfully attributed to surface tension effects.762

Effect of temperature on magnetic solitons induced by spin-transfer torque

Spin-transfer torques in a nanocontact to an extended magnetic film can create spin waves that condense to form dissipative droplet solitons. Here we report an experimental study of the temperature dependence of the current and applied field thresholds for droplet soliton formation, as well as the nanocontact's electrical characteristics associated with droplet dynamics. Nucleation requires lower current densities at lower temperatures, in contrast to typical spin-transfer-torque-induced switching between static magnetic states. Magnetoresistance and electrical noise measurements (10 MHz-1 GHz) show that droplet solitons become more stable at lower temperature. These results are of fundamental interest in understanding the influence of thermal noise on droplet solitons and have implications for the design of devices using the spin-transfer-torque effects to create and control collective spin excitations

The 2HWC HAWC Observatory Gamma Ray Catalog

We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

The Effect of Macular Hole Duration on Surgical Outcomes: An Individual Participant Data Study of Randomized Controlled Trials

Topic: To define the effect of symptom duration on outcomes in people undergoing surgery for idiopathic full-thickness macular holes (iFTMHs) by means of an individual participant data (IPD) study of randomized controlled trials (RCTs). The outcomes assessed were primary iFTMH closure and postoperative best-corrected visual acuity (BCVA). Clinical Relevance: Idiopathic full-thickness macular holes are visually disabling with a prevalence of up to 0.5%. Untreated BCVA is typically reduced to 20/200. Surgery can close holes and improve vision. Symptom duration is thought to affect outcomes with surgery, but the effect is unclear. Methods: A systematic review identified eligible RCTs that included adults with iFTMH undergoing vitrectomy with gas tamponade in which symptom duration, primary iFTMH closure, and postoperative BCVA were recorded. Bibliographic databases were searched for articles published between 2000 and 2020. Individual participant data were requested from eligible studies. Results: Twenty eligible RCTs were identified. Data were requested from all studies and obtained from 12, representing 940 eyes in total. Median symptom duration was 6 months (interquartile range, 3–10). Primary closure was achieved in 81.5% of eyes. There was a linear relationship between predicted probability of closure and symptom duration. Multilevel logistic regression showed each additional month of duration was associated with 0.965 times lower odds of closure (95% confidence interval [CI], 0.935–0.996, P = 0.026). Internal limiting membrane (ILM) peeling, ILM flap use, better preoperative BCVA, face-down positioning, and smaller iFTMH size were associated with increased odds of primary closure. Median postoperative BCVA in eyes achieving primary closure was 0.48 logarithm of the minimum angle of resolution (logMAR) (20/60). Multilevel logistic regression showed for eyes achieving primary iFTMH closure, each additional month of symptom duration was associated with worsening BCVA by 0.008 logMAR units (95% CI, 0.005–0.011, P < 0.001) (i.e., ∼1 Early Treatment Diabetic Retinopathy Study letter loss per 2 months). ILM flaps, intraocular tamponade using long-acting gas, better preoperative BCVA, smaller iFTMH size, and phakic status were also associated with improved postoperative BCVA. Conclusions: Symptom duration was independently associated with both anatomic and visual outcomes in persons undergoing surgery for iFTMH. Time to surgery should be minimized and care pathways designed to enable this

The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR

Reduction in renal ACE2 expression in subtotal nephrectomy in rats is ameliorated with ACE inhibition

Alterations within the RAS (renin–angiotensin system) are pivotal for the development of renal disease. ACE2 (angiotensin-converting enzyme 2) is expressed in the kidney and converts the vasoconstrictor AngII (angiotensin II) into Ang-(1–7), a peptide with vasodilatory and anti-fibrotic actions. Although the expression of ACE2 in the diabetic kidney has been well studied, little is known about its expression in non-diabetic renal disease. In the present study, we assessed ACE2 in rats with acute kidney injury induced by STNx (subtotal nephrectomy). STNx and Control rats received vehicle or ramipril (1 mg·kg−1 of body weight·day−1), and renal ACE, ACE2 and mas receptor gene and protein expression were measured 10 days later. STNx rats were characterized by polyuria, proteinuria, hypertension and elevated plasma ACE2 activity (all P<0.01) and plasma Ang-(1–7) (P<0.05) compared with Control rats. There was increased cortical ACE binding and medullary mas receptor expression (P<0.05), but reduced cortical and medullary ACE2 activity in the remnant kidney (P<0.05 and P<0.001 respectively) compared with Control rats. In STNx rats, ramipril reduced blood pressure (P<0.01), polyuria (P<0.05) and plasma ACE2 (P<0.01), increased plasma Ang-(1–7) (P<0.001), and inhibited renal ACE (P<0.001). Ramipril increased both cortical and medullary ACE2 activity (P<0.01), but reduced medullary mas receptor expression (P<0.05). In conclusion, our results show that ACE2 activity is reduced in kidney injury and that ACE inhibition produced beneficial effects in association with increased renal ACE2 activity. As ACE2 both degrades AngII and generates the vasodilator Ang-(1–7), a decrease in renal ACE2 activity, as observed in the present study, has the potential to contribute to the progression of kidney disease

Sensitization of cervix cancer cells to Adriamycin by Pentoxifylline induces an increase in apoptosis and decrease senescence

<p>Abstract</p> <p>Background</p> <p>Chemotherapeutic drugs like Adriamycin (ADR) induces apoptosis or senescence in cancer cells but these cells often develop resistance and generate responses of short duration or complete failure. The methylxantine drug Pentoxifylline (PTX) used routinely in the clinics setting for circulatory diseases has been recently described to have antitumor properties. We evaluated whether pretreatment with PTX modifies apoptosis and senescence induced by ADR in cervix cancer cells.</p> <p>Methods</p> <p>HeLa (HPV 18+), SiHa (HPV 16+) cervix cancer cells and non-tumorigenic immortalized HaCaT cells (control) were treated with PTX, ADR or PTX + ADR. The cellular toxicity of PTX and survival fraction were determinated by WST-1 and clonogenic assay respectively. Apoptosis, caspase activation and ADR efflux rate were measured by flow cytometry, senescence by microscopy. IκBα and DNA fragmentation were determinated by ELISA. Proapoptotic, antiapoptotic and senescence genes, as well as HPV-E6/E7 mRNA expression, were detected by time real RT-PCR. p53 protein levels were assayed by Western blot.</p> <p>Results</p> <p>PTX is toxic (WST-1), affects survival (clonogenic assay) and induces apoptosis in cervix cancer cells. Additionally, the combination of this drug with ADR diminished the survival fraction and significantly increased apoptosis of HeLa and SiHa cervix cancer cells. Treatments were less effective in HaCaT cells. We found caspase participation in the induction of apoptosis by PTX, ADR or its combination. Surprisingly, in spite of the antitumor activity displayed by PTX, our results indicate that methylxantine, <it>per se </it>does not induce senescence; however it inhibits senescence induced by ADR and at the same time increases apoptosis. PTX elevates IκBα levels. Such sensitization is achieved through the up-regulation of proapoptotic factors such as <it>caspase </it>and <it>bcl </it>family gene expression. PTX and PTX + ADR also decrease E6 and E7 expression in SiHa cells, but not in HeLa cells. p53 was detected only in SiHa cells treated with ADR.</p> <p>Conclusion</p> <p>PTX is a good inducer of apoptosis but does not induce senescence. Furthermore, PTX reduced the ADR-induced senescence and increased apoptosis in cervix cancer cells.</p