675 research outputs found
Band Structure of Topological Insulator BiSbTe1.25Se1.75
We present our angle resolved photoelectron spectroscopy (ARPES) and density
functional theory results on quaternary topological insulator (TI)
BiSbTe1.25Se1.75 (BSTS) confirming the non-trivial topology of the surface
state bands (SSBs) in this compound. We find that the SSBs, which are are
sensitive to the atomic composition of the terminating surface have a partial
3D character. Our detailed study of the band bending (BB) effects shows that in
BSTS the Dirac point (DP) shifts by more than two times compared to that in
Bi2Se3 to reach the saturation. The stronger BB in BSTS could be due to the
difference in screening of the surface charges. From momentum density curves
(MDCs) of the ARPES data we obtained an energy dispersion relation showing the
warping strength of the Fermi surface in BSTS to be intermediate between those
found in Bi2Se3 and Bi2Te3 and also to be tunable by controlling the ratio of
chalcogen/pnictogen atoms. Our experiments also reveal that the nature of the
BB effects are highly sensitive to the exposure of the fresh surface to various
gas species. These findings have important implications in the tuning of DP in
TIs for technological applications
Magnetotransport of La0.70ca0.3-xsrxmno3 (Ag): A Potential Room Temperature Bolometer and Magnetic Sensor
Here we report the optimized magneto-transport properties of polycrystalline
La0.70Ca0.3-xSrxMnO3 and their composites with Ag. The optimization was carried
out by varying the Sr and Ag contents simultaneously to achieve large
temperature coefficient of resistance (TCR) as well as low field
magneto-resistance (MR) at room temperature. Sharpest paramagnetic
(PM)-ferromagnetic (FM) and insulator-metal (IM) transition is observed in the
vicinity of the room temperature (TC=300 K=TIM) for the composition
La0.70Ca0.20Sr00.10MnO3:Ag0.20. Partial substitution of larger Sr2+ ions at the
Ca2+ ions sites controls the magnitude of the FM and IM transition
temperatures, while the Ag induces the desired sharpness in these transitions.
For the optimized composition, maximum TCR and MR are tuned to room temperature
(300 K) with the former being as high as 9% and the later being 20 and 30
percent at 5 and 10 kOe magnetic fields respectively. Such sharp single peak
(TCR= 9 percent) at room temperature can be used for the bolometric and
infrared detector applications. The achievement of large TCR and low field MR
at T~300K in polycrystalline samples is encouraging and we believe that further
improvements can be achieved in thin films, which, by virtue of their low
conduction noise, are more suitable for device applications.Comment: 11 pages Text + Figures. Suggestions/comments welcome
([email protected]
Optimal Control for Generating Quantum Gates in Open Dissipative Systems
Optimal control methods for implementing quantum modules with least amount of
relaxative loss are devised to give best approximations to unitary gates under
relaxation. The potential gain by optimal control using relaxation parameters
against time-optimal control is explored and exemplified in numerical and in
algebraic terms: it is the method of choice to govern quantum systems within
subspaces of weak relaxation whenever the drift Hamiltonian would otherwise
drive the system through fast decaying modes. In a standard model system
generalising decoherence-free subspaces to more realistic scenarios,
openGRAPE-derived controls realise a CNOT with fidelities beyond 95% instead of
at most 15% for a standard Trotter expansion. As additional benefit it requires
control fields orders of magnitude lower than the bang-bang decouplings in the
latter.Comment: largely expanded version, superseedes v1: 10 pages, 5 figure
Preventing Ovarian Cancer through early Excision of Tubes and late Ovarian Removal (PROTECTOR): protocol for a prospective non-randomised multi-center trial.
BACKGROUND: Risk-reducing salpingo-oophorectomy is the 'gold standard' for preventing tubo-ovarian cancer in women at increased risk. However, when performed in pre-menopausal women, it results in premature menopause and associated detrimental health consequences. This, together with acceptance of the central role of the fallopian tube in etiopathogenesis of high-grade serous carcinoma, by far the most common type of tubo-ovarian cancer, has led to risk-reducing early salpingectomy with delayed oophorectomy being proposed as a two-step surgical alternative for pre-menopausal women declining/delaying oophorectomy. PRIMARY OBJECTIVE: To evaluate the impact on sexual function of risk-reducing early salpingectomy, within a two-step, risk-reducing, early salpingectomy with delayed oophorectomy tubo-ovarian cancer prevention strategy in pre-menopausal women at increased risk of tubo-ovarian cancer. STUDY HYPOTHESIS: Risk-reducing early salpingectomy is non-inferior for sexual and endocrine function compared with controls; risk-reducing early salpingectomy is superior for sexual/endocrine function, non-inferior for quality-of-life, and equivalent in satisfaction to the standard risk-reducing salpingo-oophorectomy. TRIAL DESIGN: Multi-center, observational cohort trial with three arms: risk-reducing early salpingectomy with delayed oophorectomy; risk-reducing salpingo-oophorectomy; controls (no surgery). Consenting individuals undergo an ultrasound, serum CA125, and follicle-stimulating hormone measurements and provide information on medical history, family history, quality-of-life, sexual function, cancer worry, psychological well-being, and satisfaction/regret. Follow-up by questionnaire takes place annually for 3 years. Women receiving risk-reducing early salpingectomy can undergo delayed oophorectomy at a later date of their choosing, or definitely by the menopause. MAJOR INCLUSION/EXCLUSION CRITERIA: Inclusion criteria: pre-menopausal; aged >30 years; at increased risk of tubo-ovarian cancer (mutation carriers or on the basis of a strong family history); completed their family (for surgical arms). EXCLUSION CRITERIA: post-menopausal; previous bilateral salpingectomy or bilateral oophorectomy; pregnancy; previous tubal/ovarian/peritoneal malignancy; <12 months after cancer treatment; clinical suspicion of tubal/ovarian cancer at baseline. PRIMARY ENDPOINT: Sexual function measured by validated questionnaires. SAMPLE SIZE: 1000 (333 per arm). ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS: It is estimated recruitment will be completed by 2023 and results published by 2027. TRIAL REGISTRATION NUMBER: ISRCTN registry: 25 173 360 (https://doi.org/10.1186/ISRCTN25173360)
Whole-exome and HLA sequencing in Febrile infection-related epilepsy syndrome
Febrile infection‐related epilepsy syndrome (FIRES) is a devastating epilepsy characterized by new‐onset refractory status epilepticus with a prior febrile infection. We performed exome sequencing in 50 individuals with FIRES, including 27 patient–parent trios and 23 single probands, none of whom had pathogenic variants in established genes for epilepsies or neurodevelopmental disorders. We also performed HLA sequencing in 29 individuals with FIRES and 529 controls, which failed to identify prominent HLA alleles. The genetic architecture of FIRES is substantially different from other developmental and epileptic encephalopathies, and the underlying etiology remains elusive, requiring novel approaches to identify the underlying causative factors
Cable Pili and the Associated 22 Kda Adhesin Contribute to Burkholderia Cenocepacia Persistence In Vivo
Infection by Burkholderia cenocepacia in cystic fibrosis (CF) patients is associated with poor clinical prognosis. Previously, we demonstrated that one of the highly transmissible strains, BC7, expresses cable pili and the associated 22 kDa adhesin, both of which contribute to BC7 binding to airway epithelial cells. However, the contribution of these factors to induce inflammation and bacterial persistence in vivo is not known.Wild-type BC7 stimulated higher IL-8 responses than the BC7 cbl and BC7 adhA mutants in both CF and normal bronchial epithelial cells. To determine the role of cable pili and the associated adhesin, we characterized a mouse model of B. cenocepacia, where BC7 are suspended in Pseudomonas aeruginosa alginate. C57BL/6 mice were infected intratracheally with wild-type BC7 suspended in either alginate or PBS and were monitored for lung bacterial load and inflammation. Mice infected with BC7 suspended in PBS completely cleared the bacteria by 3 days and resolved the inflammation. In contrast, mice infected with BC7 suspended in alginate showed persistence of bacteria and moderate lung inflammation up to 5 days post-infection. Using this model, mice infected with the BC7 cbl and BC7 adhA mutants showed lower bacterial loads and mild inflammation compared to mice infected with wild-type BC7. Complementation of the BC7 cblS mutation in trans restored the capacity of this strain to persist in vivo. Immunolocalization of bacteria revealed wild-type BC7 in both airway lumen and alveoli, while the BC7 cbl and BC7 adhA mutants were found mainly in airway lumen and peribronchiolar region.B. cenocepacia suspended in alginate can be used to determine the capacity of bacteria to persist and cause lung inflammation in normal mice. Both cable pili and adhesin contribute to BC7-stimulated IL-8 response in vitro, and BC7 persistence and resultant inflammation in vivo
Brachypodium distachyon line Bd3-1 resistance is elicited by the barley stripe mosaic virus triple gene block 1 movement protein
Barley stripe mosaic virus North Dakota 18 (ND18), Beijing (BJ), Xinjiang (Xi), Type (TY) and CV21 strains are unable to infect the Brachypodium distachyon Bd3-1 inbred line, which harbours a resistance gene designated Bsr1, but the Norwich (NW) strain is virulent on Bd3-1. Analysis of ND18 and NW genomic RNA reassortants and RNA beta mutants demonstrates that two amino acids within the helicase motif of the triple gene block 1 (TGB1) movement protein have major effects on their Bd3-1 phenotypes. Resistance to ND18 correlates with an arginine residue at TGB1 position 390 (R-390) and a threonine at position 392 (T-392), whereas the virulent NW strain contains lysines (K) at both positions. ND18 TGB1 R390K ((ND)TGB1(R390K)) and (ND)TGB1(T392K) single substitutions, and an (ND)TGB1(R390K,T392K) double mutation resulted in systemic infections of Bd3-1. Reciprocal (ND)TGB1 substitutions into (NW)TGB1 ((NW)TGB1(K390R) and (NW)TGB1(K392T)) failed to affect virulence, implying that K-390 and K-392 compensate for each other. In contrast, an (NW)TGB1(K390R,K392T) double mutant exhibited limited vascular movement in Bd3-1, but developed prominent necrotic streaks that spread from secondary leaf veins. This phenotype, combined with the appearance of necrotic spots in certain ND18 mutants, and necrosis and rapid wilting of Bd3-1 plants after BJ strain ((BJ)TGB1(K390,T392)) inoculations, show that Bd3-1 Bsr1 resistance is elicited by the TGB1 protein and suggest that it involves a hypersensitive response
Cyclosporine-A-induced nephrotoxicity in children with minimal-change nephrotic syndrome: long-term treatment up to 10 years
The impact of cyclosporine A (CsA) therapy in patients with steroid-dependent nephrotic-syndrome (SDNS) on long-term renal function is controversial. Data beyond 5 years are rare. Long-term renal function was evaluated in children with SDNS with and without CsA therapy, especially beyond 5 years. Twenty children were treated with CsA (study group) for a mean of 5.4 ± 2.2 years (ten patients for 5–11 years). Glomerular filtration rate (GFR) was calculated before and after 3 and 12 months and at latest follow-up of therapy. Fifteen children with cyclophosphamide-treated SDNS without CsA served as controls. In the study group, GFR decreased within 12 months from 136 ± 19 to 120 ± 31, to 114 ± 14 ml/min per 1.73 m2 at latest follow-up (p < 0.0001). Patients with CsA > 5 years had a GFR of 111 ± 14 ml/min per 1.73 m2 at latest follow-up without a GFR below 90 ml/min per 1.73 m2. No CsA toxicity was found in biopsies. In the control group, GFR dropped within 3 months, from 137 ± 27 to 130 ± 24, to 126 ± 19 ml/min per 1.73 m2 at latest follow-up (p = 0.1). Patients with and without nephrotoxic CsA therapy showed a drop in GFR. In CsA-treated patients, GFR was about 12% lower at latest follow-up compared with patients without nephrotoxic therapy but always remained within normal range. CsA seems to be safe, even in long-term treatment for more than 5 years
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