309 research outputs found
Discrete-time Quantum Walks in random artificial Gauge Fields
Discrete-time quantum walks (DTQWs) in random artificial electric and
gravitational fields are studied analytically and numerically. The analytical
computations are carried by a new method which allows a direct exact analytical
determination of the equations of motion obeyed by the average density
operator. It is proven that randomness induces decoherence and that the quantum
walks behave asymptotically like classical random walks. Asymptotic diffusion
coefficients are computed exactly. The continuous limit is also obtained and
discussed.Comment: 16 pages, 9 figures. Submitted to Physica
Fermion confinement via Quantum Walks in 2D+1 and 3D+1 spacetime
We analyze the properties of a two and three dimensional quantum walk that
are inspired by the idea of a brane-world model put forward by Rubakov and
Shaposhnikov [1]. In that model, particles are dynamically confined on the
brane due to the interaction with a scalar field. We translated this model into
an alternate quantum walk with a coin that depends on the external field, with
a dependence which mimics a domain wall solution. As in the original model,
fermions (in our case, the walker), become localized in one of the dimensions,
not from the action of a random noise on the lattice (as in the case of
Anderson localization), but from a regular dependence in space. On the other
hand, the resulting quantum walk can move freely along the "ordinary"
dimension.Comment: 5 pages, 6 figure
Discrete-time quantum walks: continuous limit and symmetries
The continuous limit of one dimensional discrete-time quantum walks with
time- and space-dependent coefficients is investigated. A given quantum walk
does not generally admit a continuous limit but some families (1-jets) of
quantum walks do. All families (1-jets) admitting a continuous limit are
identified. The continuous limit is described by a Dirac-like equation or,
alternately, a couple of Klein-Gordon equations. Variational principles leading
to these equations are also discussed, together with local invariance
properties
Temporary vena cava filters in the prevention of pulmonary embolism during total hip arthroplasty
Thromboembolism constitutes one of the most dangerous complications during the immediate postoperative period of prosthetic surgery. Pharmacological prophylaxis and mechanical vascular compression are not always sufficient to protect from this surgical complication. In patients at greatest risk for thromboembolism, often with a positive history for pulmonary embolism, temporary vena cava filters may be used to reduce the incidence of vascular and pulmonary complications. However useful, these filters cannot be routinely used in orthopedic surgery. We present our results with the use of Filcard RFO2 vena cava filters in an open, randomized study of 30 patients
Immune Checkpoint Blockade in Lung Carcinoids with Aggressive Behaviour: One More Arrow in Our Quiver?
Lung carcinoids are well-differentiated and low-/intermediate-grade neuroendocrine neoplasms of the lung. Given their relative rarity, and the paucity of data available from prospective studies, no global consensus exists on the systemic treatment of these tumours. In recent years, immune checkpoint inhibitors have revolutionized cancer management and are under evaluation in patients with diverse types of neuroendocrine neoplasms. The aim of this narrative review is to analyse all available data for the use of approved immune checkpoint inhibitors in patients with lung carcinoids. We performed an extensive search for relevant data sources and found five published articles, one meeting abstract, and nine registered clinical trials indicating a growing interest of researchers in this field, and providing preliminary evidence of efficacy for combined nivolumab plus ipilimumab and durvalumab plus tremelimumab regimens in the treatment of advanced and/or metastatic lung carcinoids
Lacrimal Gland Involvement in Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome
PURPOSE:
To describe the involvement of the lacrimal gland (LG) in blepharophimosis-ptosis-epicanthus inversus syndrome (BPES).
DESIGN:
Observational, cross-sectional study.
PARTICIPANTS:
Twenty-one patients with BPES (10 female, 11 male) aged on average 15 years (range, 2-39 years), from 3 Brazilian medical centers and 1 Portuguese medical center.
METHODS:
Patients had their ocular surface evaluated with slit-lamp biomicroscopy, and tear production quantified with the Schirmer test I. The LG volumes were measured on computed tomography (CT) scans in the BPES sample and in a group of age-matched subjects imaged for nonorbital diseases. Sixteen patients were screened for mutations in the FOXL2 gene.
MAIN OUTCOME MEASURES:
Lacrimal meniscus height, Schirmer test I, presence of superficial punctate keratopathy (SPK), LG volume, and molecular analysis of the FOXL2 gene.
RESULTS:
Absence of LG was detected bilaterally in 9 patients (42.8%) and unilaterally in 2 patients (9.5%). When considering only patients with measurable LG, the median volume was 0.22 cm3 in the right eye (range, 0.06-0.36 cm3) and 0.24 cm3 in the left eye (range, 0.08-0.34 cm3). These values were significantly lower than those for the age-matched controls (median = 0.54 right eye and 0.53 left eye; P < 0.05). There was a significant association between deficiency of tear production and LG volume reduction and agenesis. Molecular analysis of the FOXL2 gene revealed the presence of 8 distinct mutations, 4 of them novel ones. A significant reduction of LG size or agenesis was associated with mutations affecting protein size (due to underlying changes in the stop codon location) or the DNA-binding forkhead domain (Fisher exact test, P = 0.021). In 3 probands, the underlying genetic defect was not found.
CONCLUSIONS:
This is the first study reporting LG volumes in BPES, describing a significant number of patients with LG agenesis. The association between alacrima and BPES is not incidental, and a thorough evaluation of tear production is recommended especially if ptosis surgery is planned.info:eu-repo/semantics/acceptedVersio
Late Endocrine and Metabolic Sequelae and LongâTerm Monitoring of Classical Hodgkin Lymphoma and Diffuse Large BâCell Lymphoma Survivors: A Systematic Review by the Fondazione Italiana Linfomi
Background: Overall survival after lymphoma has improved in recent years, but the high prevalence of late treatmentârelated sequelae has been observed as a counterpart. Method: In this systematic review, FIL researchers aimed to: (i) estimate the incidence or prevalence of late endocrineâmetabolic sequelae, (ii) evaluate the effects of modern therapeutic approaches on incidence or prevalence of late endocrineâmetabolic sequelae, and (iii) determine whether there is evidence of followâup schemes for their screening/early diagnosis in the subset of longâterm classical Hodgkin lymphoma (cHL) and diffuse large Bâcell lymphoma (DLBCL) survivors treated at adult age. The MEDLINE, Embase and the Cochrane Library databases were searched for relevant articles published up to October, 2020. The study selection process was conducted by three independent reviewers and was reported according to the Preferred Reporting Items for Systematic Reviews and MetaâAnalyses (PRISMA) guidelines. A risk of bias assessment was performed using the Cochrane tool for randomized trials and the NewcastleâOttawa Scale for observational studies. Results: In the final analysis, eight studies were included, four of which focused on thyroid disease, two on gonadal dysfunction, one on bone disease and one on metabolic syndrome. Hypothyroidism was reported in up to 60% of adult cHL survivors and was frequently recorded even with modern radiotherapy approaches. Menopause occurred in 52â72% of women after chemotherapy. An 86% reduction in vertebral density was reported following RâCHOPâlike chemotherapy. Sarcopenia and metabolic syndrome were reported in 37.9% and 60% of patients, respectively. No validated screening protocols were found for the early diagnosis of longâterm treatmentârelated endocrine and metabolic sequelae, thus the authors finally suggest the execution of screening exams according to the risk category which were identified in the epidemiologic studies
Modeling andsimulationofspeedselectiononleftventricular assist devices
The control problem for LVADs is to set pump speed such that cardiac output and pressure perfusion are within acceptable physiological ranges. However, current technology of LVADs cannot provide for a closed-loop control scheme that can make adjustments based on the patient\u27s level of activity. In this context, the SensorART Speed Selection Module (SSM) integrates various hardware and software components in order to improve the quality of the patients\u27 treatment and the workflow of the specialists. It enables specialists to better understand the patient-device interactions, and improve their knowledge. The SensorART SSM includes two tools of the Specialist Decision Support System (SDSS); namely the Suction Detection Tool and the Speed Selection Tool. A VAD Heart Simulation Platform (VHSP) is also part of the system. The VHSP enables specialists to simulate the behavior of a patient?s circulatory system, using different LVAD types and functional parameters. The SDSS is a web-based application that offers specialists with a plethora of tools for monitoring, designing the best therapy plan, analyzing data, extracting new knowledge and making informative decisions. In this paper, two of these tools, the Suction Detection Tool and Speed Selection Tool are presented. The former allows the analysis of the simulations sessions from the VHSP and the identification of issues related to suction phenomenon with high accuracy 93%. The latter provides the specialists with a powerful support in their attempt to effectively plan the treatment strategy. It allows them to draw conclusions about the most appropriate pump speed settings. Preliminary assessments connecting the Suction Detection Tool to the VHSP are presented in this paper
Viscoelastic gels of guar and xanthan gum mixtures provide long-term stabilization of iron micro- and nanoparticles
Iron micro- and nanoparticles used for groundwater remediation and medical applications are prone to fast aggregation and sedimentation. Diluted single biopolymer water solutions of guar gum (GG) or xanthan gum (XG) can stabilize these particles for few hours providing steric repulsion and by increasing the viscosity of the suspension. The goal of the study is to demonstrate that amending GG solutions with small amounts of XG (XG/GG weight ratio 1:19; 3 g/L of total biopolymer concentration) can significantly improve the capability of the biopolymer to stabilize highly concentrated iron micro- and nanoparticle suspensions. The synergistic effect between GG and XG generates a viscoelastic gel that can maintain 20 g/L iron particles suspended for over 24 h. This is attributed to (i) an increase in the static viscosity, (ii) a combined polymer structure the yield stress of which contrasts the downward stress exerted by the iron particles, and (iii) the adsorption of the polymers to the iron surface having an anchoring effect on the particles. The XG/GG viscoelastic gel is characterized by a marked shear thinning behavior. This property, coupled with the low biopolymer concentration, determines small viscosity values at high shear rates, facilitating the injection in porous media. Furthermore, the thermosensitivity of the soft elastic polymeric network promotes higher stability and longer storage times at low temperatures and rapid decrease of viscosity at higher temperatures. This feature can be exploited in order to improve the flowability and the delivery of the suspensions to the target as well as to effectively tune and control the release of the iron particle
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