48 research outputs found
Comparison between the two models of dephasing in mesoscopic systems
In mesoscopic systems to study the role of inelastic scattering on the phase
coherent motion of electrons two phenomenological models have been proposed. In
the first one, due to B\"uttiker, one adds a voltage probe into the system (or
in the scattering matrix). The second model invokes the complex (or optical)
potential in the system Hamiltonian. Studying a simple geometry of a metallic
loop in the presence of Aharonov-Bohm magnetic flux, we show that the two probe
conductance is symmetric in the reversal of the magnetic field in B\"uttiker's
approach. Whereas the two probe conductance within the complex potential model
is asymmetric in the magnetic flux reversal contrary to the expected behavior.Comment: 11 pages RevTex, 4 figures inculded, Communicated to PR
Aharonov-Bohm oscillations and spin transport in a mesoscopic ring with a magnetic impurity
We present a detailed analysis of the Aharonov-Bohm (AB) interference
oscillations manifested through transmission of an electron in a mesoscopic
ring with a magnetic impurity atom inserted in one of its arms. The spin
polarization transport is also studied. The electron interacts with the
impurity through the exchange interaction leading to exchange spin-flip
scattering. Transmission in the spin-flipped and spin-unflipped channels are
explicitly calculated. We show that the entanglement between electron and
spin-flipper states lead to a reduction of AB oscillations in spite of absence
of any inelastic scattering. The spin-conductance (related to spin-polarized
transmission coefficient) is asymmetric in the flux reversal as opposed to the
two probe conductance which is symmetric under flux reversal. We point out
certain limitations of this model in regard to the general notion of dephasing
in quantum mechanics.Comment: 6 pages RevTeX, 9 eps figures included, enlarged version of
cond-mat/000741
Small Quadrupole Deformation for the Dipole Bands in 112In
High spin states in In were investigated using Mo(O,
p3n) reaction at 80 MeV. The excited level have been observed up to 5.6 MeV
excitation energy and spin 20 with the level scheme showing three
dipole bands. The polarization and lifetime measurements were carried out for
the dipole bands. Tilted axis cranking model calculations were performed for
different quasi-particle configurations of this doubly odd nucleus. Comparison
of the calculations of the model with the B(M1) transition strengths of the
positive and negative parity bands firmly established their configurations.Comment: 10 pages, 11 figures, 2 table
Characterization of a trimeric light-harvesting complex in the diatom Phaeodactylum tricornutum built of FcpA and FcpE proteins
Fucoxanthin chlorophyll proteins (Fcps), the light-harvesting antennas of heterokont algae, are encoded by a multigene family and are highly similar with respect to their molecular masses as well as to their pigmentation, making it difficult to purify single Fcps. In this study, a hexa-histidine tag was genetically added to the C-terminus of the FcpA protein of the pennate diatom Phaeodactylum tricornutum. A transgenic strain expressing the recombinant His-tagged FcpA protein in addition to the endogenous wild type Fcps was created. This strategy allowed, for the first time, the purification of a specific, stable trimeric Fcp complex. In addition, a pool of various trimeric Fcps was also purified from the wild-type cells using sucrose density gradient ultracentrifugation and gel filtration. In both the His-tagged and the wild-type Fcps, excitation energy coupling between fucoxanthin and chlorophyll a was intact and the existence of a chlorophyll a/fucoxanthin excitonic dimer was demonstrated using circular dichroism spectroscopy. Mass spectrometric analyses of the trimeric His-tagged complex indicated that it is composed of FcpA and FcpE polypeptides. It is confirmed here that a trimer is the basic organizational unit of Fcps in P. tricornutum. From circular dichroism spectra, it is proposed that the organization of the pigments on the polypeptide backbone of Fcps is a conserved feature in the case of chlorophyll a/c containing algae
Study of nuclei in the vicinity of the "Island of Inversion" through fusion-evaporation reaction
We report the first observation of high-spin states in nuclei in the vicinity
of the "island of inversion", populated via the 18O+18O fusion reaction at an
incident beam energy of 34 MeV. The fusion reaction mechanism circumvents the
limitations of non-equilibrated reactions used to populate these nuclei.
Detailed spin-parity measurements in these difficult to populate nuclei have
been possible from the observed coincidence anisotropy and the linear
polarization measurements. The spectroscopy of 33,34P and 33S is presented in
detail along with the results of calculations within the shell model framework
Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial
Background: The EMPA KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population. Methods: EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110. Findings: Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5–2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62–0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16–1·59), representing a 50% (42–58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1). Interpretation: In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease. Funding: Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council
Rehabilitation versus surgical reconstruction for non-acute anterior cruciate ligament injury (ACL SNNAP): a pragmatic randomised controlled trial
BackgroundAnterior cruciate ligament (ACL) rupture is a common debilitating injury that can cause instability of the knee. We aimed to investigate the best management strategy between reconstructive surgery and non-surgical treatment for patients with a non-acute ACL injury and persistent symptoms of instability.MethodsWe did a pragmatic, multicentre, superiority, randomised controlled trial in 29 secondary care National Health Service orthopaedic units in the UK. Patients with symptomatic knee problems (instability) consistent with an ACL injury were eligible. We excluded patients with meniscal pathology with characteristics that indicate immediate surgery. Patients were randomly assigned (1:1) by computer to either surgery (reconstruction) or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment), stratified by site and baseline Knee Injury and Osteoarthritis Outcome Score—4 domain version (KOOS4). This management design represented normal practice. The primary outcome was KOOS4 at 18 months after randomisation. The principal analyses were intention-to-treat based, with KOOS4 results analysed using linear regression. This trial is registered with ISRCTN, ISRCTN10110685, and ClinicalTrials.gov, NCT02980367.FindingsBetween Feb 1, 2017, and April 12, 2020, we recruited 316 patients. 156 (49%) participants were randomly assigned to the surgical reconstruction group and 160 (51%) to the rehabilitation group. Mean KOOS4 at 18 months was 73·0 (SD 18·3) in the surgical group and 64·6 (21·6) in the rehabilitation group. The adjusted mean difference was 7·9 (95% CI 2·5–13·2; p=0·0053) in favour of surgical management. 65 (41%) of 160 patients allocated to rehabilitation underwent subsequent surgery according to protocol within 18 months. 43 (28%) of 156 patients allocated to surgery did not receive their allocated treatment. We found no differences between groups in the proportion of intervention-related complications.InterpretationSurgical reconstruction as a management strategy for patients with non-acute ACL injury with persistent symptoms of instability was clinically superior and more cost-effective in comparison with rehabilitation management