Critical behavior of ion mobilities near the superfluid transition

Measurements are reported of the mobilities of helium ions in superfluid helium very close to the λ transition. The mobilities of both positive and negative ions appear to be singular in the sense of having infinite slope at the transition. The measurements are made by a new differential technique, based on the space-charge-limited method, which makes possible a sensitivity to changes in mobility of the order of parts in 104. This allows mobility measurements into the range |ε|<10-4, where ε=(T/Tλ)-1. Most of the reported measurements are taken along isotherms which cross the λ line at elevated pressures, although a series at saturated vapor pressure is also reported. Means of transforming the data between various thermodynamic paths are discussed. Uncertainty as to which thermodynamic path should be considered fundamental together with experimental problems in the technique at this stage in its development make quantitative assessment of the singularity difficult. However, if we assume a limiting form (μ-μλ)/μλ∼(-ε)ρ′, where μ is the mobility and μλ its value at the transition, we find for the exponent ρ′=0.94±0.02

A variational technique for the computation of the vibration frequencies of mechanical systems governed by nonsymmetric matrices

AbstractIn this paper an algorithm for the solution of linear eigenvalue problems governed by ill-conditioned nonsymmetric matrices that are typical in dynamic structural analysis in the presence of nonconservative loads is proposed. The real eigenpairs (x,λ) are formulated as the minimizers of a suitable non-negative functional, which plays a role analogous to that of the Raleigh quotient for positive definite matrices. The proposed method, which is similar to a Rayleigh iterative scheme, has proven itself to be substancially unaffected by extremely high dispersions of the real eigenvalues. The method is illustrated by means of examples that correspond to beams subject to nonconservative loads

The challenge of perioperative pain management in opioid-tolerant patients

The increasing number of opioid users among chronic pain patients, and opioid abusers among the general population, makes perioperative pain management challenging for health care professionals. Anesthesiologists, surgeons, and nurses should be familiar with some pharmacological phenomena which are typical of opioid users and abusers, such as tolerance, physical dependence, hyperalgesia, and addiction. Inadequate pain management is very common in these patients, due to common prejudices and fears. The target of preoperative evaluation is to identify comorbidities and risk factors and recognize signs and symptoms of opioid abuse and opioid withdrawal. Clinicians are encouraged to plan perioperative pain medications and to refer these patients to psychiatrists and addiction specialists for their evaluation. The aim of this review was to give practical suggestions for perioperative management of surgical opioid-tolerant patients, together with schemes of opioid conversion for chronic pain patients assuming oral or transdermal opioids, and patients under maintenance programs with methadone, buprenorphine, or naltrexone

Federico Cesi's Mycological Codex and its copies

n/

Secukinumab for Psoriasis in Obese Patients: Minireview and Clinical Experience

Psoriasis (PsO) has been associated with obesity, and its severity increases in obese subjects. The link between psoriatic condition and obesity is based on shared pathophysiological pathways where local and systemic inflammation promote each other; PsO is an inflammatory, immune-mediated disease, and the adipose tissue is the source of proinflammatory adipokines. Moreover, psoriatic arthritis (PsA) is an important comorbidity of PsO that reduces quality of life and makes difficult the patient's management. Treatment of obese subjects with moderate to severe PsO, even more if PsA is present, is challenging because of reduced efficacy of several systemic drugs and increased risk of adverse events. Secukinumab, a monoclonal antibody that selectively binds to and neutralizes interleukin 17A, shows efficacy on PsO in all body weight groups, even in the highest, whose response has a slight downward trend. Clinical features of two obese subjects, affected by PsO and PsA, successfully treated with secukinumab, are described

Efficacy of topical imiquimod 3.75% in the treatment of actinic keratosis of the scalp in immunosuppressed patients: our case series

AbstractBackground: Actinic keratoses (AK) represent common cutaneous lesions, appearing in 'Field cancerization areas' and potentially evolving toward invasive neoplasm. Immunosuppressed patients ..

Effects of Thermal Variations on the Tensile Behavior of FRCM Strengthening Systems

Use of fabric-reinforced cementitious matrices (FRCM) is a very efficient strengthening solution for improving the structural behavior of existing masonry elements. FRCM are capable of improving the load-bearing capacity of masonry panels, at the same time providing more ductile behavior. However, the mechanical performances of these materials could be significantly affected by environmental conditions, such as exposure to thermal variations. This aspect should be properly assessed by guidelines and standards devoted to the design of strengthening interventions. Within this framework, the objective of the present research was to evaluate the effect of a temperature increase on the tensile behavior of various FRCM systems, composed of steel, basalt, or aramid-glass fibers and lime-based or cement-based mortar matrices. Tensile tests were performed for each system under different thermal conditioning protocols, comprising different target temperatures, exposure periods, test conditions, and adopted heating sources. The test results showed that the effect of temperature is more evident in the first phases of the tensile tests, that is, during the uncracked phase and the mortar matrix cracking phase, whereas it is less significant in the final phase, which was more related to fiber behavior. Comparisons between the different thermal conditioning procedures are critically discussed within the paper and, in light of the results obtained, recommendations are included to optimize the testing procedures for future research and qualification procedures

Polar catastrophe and electronic reconstructions at the LaAlO3/SrTiO3 interface: evidence from optical second harmonic generation

The so-called "polar catastrophe", a sudden electronic reconstruction taking place to compensate for the interfacial ionic polar discontinuity, is currently considered as a likely factor to explain the surprising conductivity of the interface between the insulators LaAlO3 and SrTiO3. We applied optical second harmonic generation, a technique that a priori can detect both mobile and localized interfacial electrons, to investigating the electronic polar reconstructions taking place at the interface. As the LaAlO3 film thickness is increased, we identify two abrupt electronic rearrangements: the first takes place at a thickness of 3 unit cells, in the insulating state; the second occurs at a thickness of 4-6 unit cells, i.e., just above the threshold for which the samples become conducting. Two possible physical scenarios behind these observations are proposed. The first is based on an electronic transfer into localized electronic states at the interface that acts as a precursor of the conductivity onset. In the second scenario, the signal variations are attributed to the strong ionic relaxations taking place in the LaAlO3 layer