287 research outputs found
Phonon dispersion of Mo-stabilized γ-U measured using inelastic x-ray scattering.
We have measured the room-temperature phonon spectrum of Mo-stabilized γ-U. The dispersion curves show unusual softening near the H point, q = [1/2, 1/2, 1/2], which may derive from the metastability of the γ-U phase or from strong electron-phonon coupling. Near the zone center, the dispersion curves agree well with theory, though significant differences are observed away from the zone center. The experimental phonon density of states is shifted to higher energy compared to theory and high-temperature neutron scattering. The elastic constants of γ-UMo are similar to those of body-centered cubic elemental metals
Rate theory of acceleration of the defect annealing driven by discrete breathers
Novel mechanisms of defect annealing in solids are discussed, which are based
on the large amplitude anharmonic lattice vibrations, a.k.a. intrinsic
localized modes or discrete breathers (DBs). A model for amplification of
defect annealing rate in Ge by low energy plasma-generated DBs is proposed, in
which, based on recent atomistic modelling, it is assumed that DBs can excite
atoms around defects rather strongly, giving them energy for
100 oscillation periods. This is shown to result in the amplification of
the annealing rates proportional to the DB flux, i.e. to the flux of ions (or
energetic atoms) impinging at the Ge surface from inductively coupled plasma
(ICP)Comment: 18 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1406.394
AMN107 (nilotinib): a novel and selective inhibitor of BCR-ABL
Chronic myelogenous leukaemia (CML) and Philadelphia chromosome positive (Ph+) acute lymphoblastic leukaemia (ALL) are caused by the BCR-ABL oncogene. Imatinib inhibits the tyrosine kinase activity of the BCR-ABL protein and is an effective, frontline therapy for chronic-phase CML. However, accelerated or blast-crisis phase CML patients and Ph+ ALL patients often relapse due to drug resistance resulting from the emergence of imatinib-resistant point mutations within the BCR-ABL tyrosine kinase domain. This has stimulated the development of new kinase inhibitors that are able to over-ride resistance to imatinib. The novel, selective BCR-ABL inhibitor, AMN107, was designed to fit into the ATP-binding site of the BCR-ABL protein with higher affinity than imatinib. In addition to being more potent than imatinib (IC50<30 nM) against wild-type BCR-ABL, AMN107 is also significantly active against 32/33 imatinib-resistant BCR-ABL mutants. In preclinical studies, AMN107 demonstrated activity in vitro and in vivo against wild-type and imatinib-resistant BCR-ABL-expressing cells. In phase I/II clinical trials, AMN107 has produced haematological and cytogenetic responses in CML patients, who either did not initially respond to imatinib or developed imatinib resistance. Dasatinib (BMS-354825), which inhibits Abl and Src family kinases, is another promising new clinical candidate for CML that has shown good efficacy in CML patients. In this review, the early characterisation and development of AMN107 is discussed, as is the current status of AMN107 in clinical trials for imatinib-resistant CML and Ph+ ALL. Future trends investigating prediction of mechanisms of resistance to AMN107, and how and where AMN107 is expected to fit into the overall picture for treatment of early-phase CML and imatinib-refractory and late-stage disease are discussed
Elastically driven, intermittent microscopic dynamics in soft solids
Soft solids with tunable mechanical response are at the core of new material
technologies, but a crucial limit for applications is their progressive aging
over time, which dramatically affects their functionalities. The generally
accepted paradigm is that such aging is gradual and its origin is in slower
than exponential microscopic dynamics, akin to the ones in supercooled liquids
or glasses. Nevertheless, time- and space-resolved measurements have provided
contrasting evidence: dynamics faster than exponential, intermittency, and
abrupt structural changes. Here we use 3D computer simulations of a microscopic
model to reveal that the timescales governing stress relaxation respectively
through thermal fluctuations and elastic recovery are key for the aging
dynamics. When thermal fluctuations are too weak, stress heterogeneities
frozen-in upon solidification can still partially relax through elastically
driven fluctuations. Such fluctuations are intermittent, because of strong
correlations that persist over the timescale of experiments or simulations,
leading to faster than exponential dynamics.Comment: 7 pages, Supplementary Information include
Deleted in Liver Cancer 2 (DLC2) Was Dispensable for Development and Its Deficiency Did Not Aggravate Hepatocarcinogenesis
DLC2 (deleted in liver cancer 2), a Rho GTPase-activating protein, was previously shown to be underexpressed in human hepatocellular carcinoma and has tumor suppressor functions in cell culture models. We generated DLC2-deficient mice to investigate the tumor suppressor role of DLC2 in hepatocarcinogenesis and the function of DLC2 in vivo. In this study, we found that, unlike homologous DLC1, which is essential for embryonic development, DLC2 was dispensable for embryonic development and DLC2-deficient mice could survive to adulthood. We also did not observe a higher incidence of liver tumor formation or diethylnitrosamine (DEN)-induced hepatocarcinogenesis in DLC2-deficient mice. However, we observed that DLC2-deficient mice were smaller and had less adipose tissue than the wild type mice. These phenotypes were not due to reduction of cell size or defect in adipogenesis, as observed in the 190B RhoGAP-deficient mouse model. Together, these results suggest that deficiency in DLC2 alone does not enhance hepatocarcinogenesis
Coupling and Elastic Loading Affect the Active Response by the Inner Ear Hair Cell Bundles
Active hair bundle motility has been proposed to underlie the amplification mechanism in the auditory endorgans of non-mammals and in the vestibular systems of all vertebrates, and to constitute a crucial component of cochlear amplification in mammals. We used semi-intact in vitro preparations of the bullfrog sacculus to study the effects of elastic mechanical loading on both natively coupled and freely oscillating hair bundles. For the latter, we attached glass fibers of different stiffness to the stereocilia and observed the induced changes in the spontaneous bundle movement. When driven with sinusoidal deflections, hair bundles displayed phase-locked response indicative of an Arnold Tongue, with the frequency selectivity highest at low amplitudes and decreasing under stronger stimulation. A striking broadening of the mode-locked response was seen with increasing stiffness of the load, until approximate impedance matching, where the phase-locked response remained flat over the physiological range of frequencies. When the otolithic membrane was left intact atop the preparation, the natural loading of the bundles likewise decreased their frequency selectivity with respect to that observed in freely oscillating bundles. To probe for signatures of the active process under natural loading and coupling conditions, we applied transient mechanical stimuli to the otolithic membrane. Following the pulses, the underlying bundles displayed active movement in the opposite direction, analogous to the twitches observed in individual cells. Tracking features in the otolithic membrane indicated that it moved in phase with the bundles. Hence, synchronous active motility evoked in the system of coupled hair bundles by external input is sufficient to displace large overlying structures
A multidisciplinary program for achieving lipid goals in chronic hemodialysis patients
BACKGROUND: There is little information on how target lipid levels can be achieved in end stage renal disease (ESRD) patients in a systematic, multidisciplinary fashion. METHODS: We retrospectively reviewed a pharmacist-directed hyperlipidemia management program for chronic hemodialysis (HD) patients. All 26 adult patients on chronic HD at a tertiary care medical facility were entered into the program. A clinical pharmacist was responsible for laboratory monitoring, patient counseling, and the initiation and dosage adjustment of an appropriate 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor (statin) using a dosing algorithm and monitoring guidelines. The low-density lipoprotein (LDL) cholesterol goal was ≤ 100 mg/dl. A renal dietitian provided nutrition counseling and the nephrologist was notified of potential or existing drug interactions or adverse drug reactions (ADRs). Patients received a flyer containing lipid panel results to encourage compliance. Data was collected at program initiation and for 6 months thereafter. RESULTS: At the start of the program, 58% of patients were at target LDL cholesterol. At 6 months, 88% had achieved target LDL (p = 0.015). Mean LDL cholesterol decreased from 96 ± 5 to 80 ± 3 mg/dl (p < 0.01), and mean total cholesterol decreased from 170 ± 7 to 151 ± 4 mg/dl (p < 0.01). Fifteen adjustments in drug therapy were made. Eight adverse drug reactions were identified; 2 required drug discontinuation or an alternative agent. Physicians were alerted to 8 potential drug-drug interactions, and appropriate monitoring was performed. CONCLUSIONS: Our findings demonstrate both feasibility and efficacy of a multidisciplinary approach in management of hyperlipidemia in HD patients
Complications after hip arthroplasty and the association with hospital procedure volume: A nationwide retrospective cohort study on 50,080 total hip replacements with a follow-up of 3 months after surgery
Background and purpose: It has been suggested that a higher procedure volume is associated with less complications af
Discrete breathers in and related models
We touch upon the wide topic of discrete breather formation with a special
emphasis on the the model. We start by introducing the model and
discussing some of the application areas/motivational aspects of exploring time
periodic, spatially localized structures, such as the discrete breathers. Our
main emphasis is on the existence, and especially on the stability features of
such solutions. We explore their spectral stability numerically, as well as in
special limits (such as the vicinity of the so-called anti-continuum limit of
vanishing coupling) analytically. We also provide and explore a simple, yet
powerful stability criterion involving the sign of the derivative of the energy
vs. frequency dependence of such solutions. We then turn our attention to
nonlinear stability, bringing forth the importance of a topological notion,
namely the Krein signature. Furthermore, we briefly touch upon linearly and
nonlinearly unstable dynamics of such states. Some special aspects/extensions
of such structures are only touched upon, including moving breathers and
dissipative variations of the model and some possibilities for future work are
highlighted
Probiotics [LGG-BB12 or RC14-GR1] versus placebo as prophylaxis for urinary tract infection in persons with spinal cord injury [ProSCIUTTU]: a randomised controlled trial
© 2019, The Author(s). Study design: Randomised double-blind factorial-design placebo-controlled trial. Objective: Urinary tract infections (UTIs) are common in people with spinal cord injury (SCI). UTIs are increasingly difficult to treat due to emergence of multi-resistant organisms. Probiotics are efficacious in preventing UTIs in post-menopausal women. We aimed to determine whether probiotic therapy with Lactobacillus reuteri RC-14+Lactobacillus GR-1 (RC14-GR1) and/or Lactobacillus rhamnosus GG+Bifidobacterium BB-12 (LGG-BB12) are effective in preventing UTI in people with SCI. Setting: Spinal units in New South Wales, Australia with their rural affiliations. Methods: We recruited 207 eligible participants with SCI and stable neurogenic bladder management. They were randomised to one of four arms: RC14-GR1+LGG-BB12, RC14-GR1+placebo, LGG-BB12+ placebo or double placebos for 6 months. Randomisation was stratified by bladder management type and inpatient or outpatient status. The primary outcome was time to occurrence of symptomatic UTI. Results: Analysis was based on intention to treat. Participants randomised to RC14-GR1 had a similar risk of UTI as those not on RC14-GR1 (HR 0.67; 95% CI: 0.39–1.18; P = 0.17) after allowing for pre-specified covariates. Participants randomised to LGG-BB12 also had a similar risk of UTI as those not on LGG-BB12 (HR 1.29; 95% CI: 0.74–2.25; P = 0.37). Multivariable post hoc survival analysis for RC14-GR1 only vs. the other three groups showed a potential protective effect (HR 0.46; 95% CI: 0.21–0.99; P = 0.03), but this result would need to be confirmed before clinical application. Conclusion: In this RCT, there was no effect of RC14-GR1 or LGG-BB12 in preventing UTI in people with SCI
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