A general interpolation scheme for thermal fluctuations in superconductors

We present a general interpolation theory for the phenomenological effects of thermal fluctuations in superconductors. Fluctuations are described by a simple gauge invariant extension of the gaussian effective potential for the Ginzburg-Landau static model. The approach is shown to be a genuine variational method, and to be stationary for infinitesimal gauge variations around the Landau gauge. Correlation and penetration lengths are shown to depart from the mean field behaviour in a more or less wide range of temperature below the critical regime, depending on the class of material considered. The method is quite general and yields a very good interpolation of the experimental data for very different materials.Comment: some misprints have been corrected in Eq.(15),(19); more references and comments have been adde

Gaussian Effective Potential and superconductivity

The Gaussian Effective Potential in a fixed transverse unitarity gauge is studied for the static three-dimensional U(1) scalar electrodynamics (Ginzburg-Landau phenomenological theory of superconductivity). In the broken-symmetry phase the mass of the electromagnetic field (inverse penetration depth) and the mass of the scalar field (inverse correlation length) are both determined by solution of the coupled variational equations. At variance with previous calculations, the choice of a fixed unitarity gauge prevents from the occurrence of any unphysical degree of freedom. The theory provides a nice interpolation of the experimental data when approaching the critical region, where the standard mean-field method is doomed to failure

Three Dimensional Distorted Black Holes

We present three-dimensional, {\it non-axisymmetric} distorted black hole initial data which generalizes the axisymmetric, distorted, non-rotating [Bernstein93a] and rotating [Brandt94a] single black hole data developed by Bernstein, Brandt, and Seidel. These initial data should be useful for studying the dynamics of fully 3D, distorted black holes, such as those created by the spiraling coalescence of two black holes. We describe the mathematical construction of several families of such data sets, and show how to construct numerical solutions. We survey quantities associated with the numerically constructed solutions, such as ADM masses, apparent horizons, measurements of the horizon distortion, and the maximum possible radiation loss ($MRL$).Comment: 23 pages, 12 figures, accepted for publication in Classical and Quantum Gravit

Static performances of timber-and bamboo-concrete composite beams: A critical review of experimental results

The use of composite beams made with traditional concrete and bio-based materials (such as timber and bamboo) is a valuable solution to reduce the environmental impact of the building sector. Timber-Concrete Composite (TCC) beams have been used for decades in structural applications such as new buildings, refurbishment of old timber structures, and bridges. Recently, different researchers suggested composite beams based on engineered bamboo, commonly named Bamboo-Concrete Composite (BCC) beams. This study presents a systematic comparison of structural performances and connection behavior of TCC and BCC beams under short-term static load. TCCs beams are compared to BCC ones using similar shear connectors. The most important aspects of the two composite systems are compared: mechanical behavior of connectors and structural behaviors of full-scale composite beams (e.g., failure modes, connection stiffness, connection shear strength, ultimate load-carrying capacity, maximum deflection and composite efficiency). This comprehensive review indicates that BCC beams have similar or even better structural performances compared with TCC

Modelling trends in digit preference patterns

Digit preference is the habit of reporting certain end digits more often than others. If such a misreporting pattern is a concern, then measures to reduce digit preference can be taken and monitoring changes in digit preference becomes important. We propose a two-dimensional penalized composite link model to estimate the true distributions unaffected by misreporting, the digit preference pattern and a trend in the preference pattern simultaneously. A transfer pattern is superimposed on a series of smooth latent distributions and is modulated along a second dimension. Smoothness of the latent distributions is enforced by a roughness penalty. Ridge regression with an L1-penalty is used to extract the misreporting pattern, and an additional weighted least squares regression estimates the modulating trend vector. Smoothing parameters are selected by the Akaike information criterion. We present a simulation study and apply the model to data on birth weight and on self-reported weight of adults

Single use instruments for total knee arthroplasty

Aim Total knee arthroplasty represents a procedure that is successfully performed to relieve functional limitation and pain in advanced stages of osteoarthritis. In the next 20 years the number of these procedures will be increased about four times. Patient specific instrumentation (PSI) has been introduced in the past years. The aim of this study was to evaluate whether SUI are more useful in clinical, organizational and economic terms. Methods A database search about single use instrumentation (SUI) was conducted on PubMed and Google Scholar for the period 2010-2020 using the following key “total knee replacement”, “total knee arthroplasty”, “single use instruments”, and “disposable instruments”. The results of the selected studies were classified according to clinical, economic and organizational criteria. Results The main advantage of SUI has been reported to reduce costs, timely turnover of operating rooms, maximizing the operating room utilization and patient throughput, improving the number of outpatient total joint replacements. No difference has been found other than with regard to conventional instruments in terms of clinical outcome such as hip-knee-ankle angle and other radio-graphic parameters, Oxford Knee Score, while a decreased infection rate has been demonstrated. Regarding the economic aspect, a reduction of direct and indirect reduction of costs has been shown for the cost of instruments reprocessing, tray sterilization, 90-day infection rate. Conclusion The SUI can be an alternative to conventional instruments, but there are still few studies in the literature regarding clinical outcomes

Fractional order hereditariness of knee human ligament and tendon

Anterior Cruciate Ligament (ACL) is one of the four major ligaments in the knee, playing a critical role in stabilizing the joint. ACL is highly susceptible to injury, overall during sport activities, often precipitating catastrophic long-term joint outcomes. The ideal replacement graft for a torn ACL would restore native anatomy and function to the knee. Most commonly used autograft and allograft, including patellar tendon (P) and hamstring tendon (H) graft, or bioengineered synthetic grafts, may substantially alter the biomechanics of the knee, permitting a return to only moderate physical activities [1]. Main issues are the sub-optimal graft properties [2] and a still incomplete biomechanics characterization [1]. The goal of the present work is to fully characterize and compare the viscoelastic behavior of the ACL and natural/artificial grafts in order to highlight the differences that should be overcome to achieve a successful biomechanical performance and an ideal graft design

Detection of possible factors favouring the evolution of migraine without aura into chronic migraine

In a minority of cases, the natural history of migraine without aura (MO) is characterised over time by its evolution into a form of chronic migraine (CM). In order to detect the possible factors predicting this negative evolution of MO, we searched in our Headache Centre files for all clinical records that met the following criteria: (a) first visit between 1976 and 1998; (b) diagnosis of MO or of common migraine at the first observation, with or without association with other primary headache types; (c) <15 days per month of migraine at the first observation; and (d) at least one follow-up visit at least 10 years after the first visit. The patients thus identified were then divided into two groups based on a favourable/steady evolution (Group A: n = 243, 195 women and 48 men) or an unfavourable evolution (Group B: n = 72, 62 women and 10 men) of their migraine over time. In the two groups, we compared various clinical parameters that were present at the first observation or emerged at the subsequent follow-up visits. The parameters that were statistically significantly more frequent in Group B--and can therefore be considered possible negative prognostic factors--were: (a) ≥ 10 days per month of migraine at the first observation; (b) presence of depression at the first visit in males; and (c) onset of depression or arterial hypertension after the first observation but before transformation to CM in females. Based on these findings, in MO patients the high frequency of migraine attacks, comorbidity with depression, and the tendency to develop arterial hypertension should require particular attention and careful management to prevent evolution into CM

Frequency dependence of the microwave surface resistance of MgB2 by coaxial cavity resonator

We report on the microwave (mw) properties of a cylindrical MgB2 rod prepared by the reactive liquid Mg infiltration technology. The MgB2 rod, 94.3 mm long, is used as inner conductor of a coaxial cavity having a Cu tube as external conductor. By analyzing the resonance curves of the cavity in the different resonant modes and at different temperatures, we have determined the temperature dependence of the mw surface resistance, Rs, of the MgB2 material, at fixed frequencies, and the frequency dependence of Rs, at fixed temperatures. Our results show that the Rs(f) curves follow a f^n law, where n decreases on increasing the temperature, starting from n=2, at T=4.2 K, down to n=0.7 at T>Tc. The double gap nature of MgB2 manifests itself in the presence of a wide low-T tail in the R(T) curves, which can be ascribed to the quasiparticles thermally excited through the pi gap even at relatively low temperatures