Kelvin Wave Cascade and Decay of Superfluid Turbulence

Kelvin waves (kelvons)--the distortion waves on vortex lines--play a key part in the relaxation of superfluid turbulence at low temperatures. We present a weak-turbulence theory of kelvons. We show that non-trivial kinetics arises only beyond the local-induction approximation and is governed by three-kelvon collisions; corresponding kinetic equation is derived. On the basis of the kinetic equation, we prove the existence of Kolmogorov cascade and find its spectrum. The qualitative analysis is corroborated by numeric study of the kinetic equation. The application of the results to the theory of superfluid turbulence is discussed.Comment: 4 pages, RevTe

(Not) Advising Corporate Officers about Fiduciary Duties

This Article explores the intersection of an important, unresolved corporate law issue and an overlooked professional responsibility issue persistently arising in the corporate milieu. The corporate law question currently unaddressed in Delaware law is whether the fiduciary duties of corporate officers, as agents, are the same as, or different from, the fiduciary duties of corporate directors. A related question is whether, in reviewing officer conduct, courts will apply the business judgment rule in the same broad (and protective) manner in which it is applied to assessing director behavior. The professional responsibility issue concerns whether, and how well, lawyers are advising corporate officers about their fiduciary duties. In recent years, much attention has been given to the professional obligations of a corporate lawyer upon learning, ex post, of corporate wrongdoing, including director and officer breaches of fiduciary duty. Virtually no attention has been paid to whether, ex ante, lawyers are adequately helping to prevent such misconduct by fully and properly advising corporate officers as to the scope and thrust of their fiduciary duties. Fiduciary duties, as an element for shaping officer conduct to promote healthy corporate governance, are of little preventive value if not properly transmitted to officers, given that officers are unlikely on their own to understand those duties. As is the case with directors, lawyers are the obvious means by which such communications to officers would be expected to occur. How well are they fulfilling this vital role? We obtained information on this subject in two ways. First, as a pilot project we sent a survey questionnaire to corporate lawyers serving primarily as outside legal counsel in major U.S. metropolitan areas. We intend to later survey in-house counsel by means of a separate questionnaire. Second, we examined the websites of fifteen major law firms to learn what they say about themselves on the topic of advising corporate officers as to fiduciary duties. Overall, the results from our initial survey and website research suggest that many lawyers do not provide full-bodied fiduciary duty advice to officers in their capacity as officers at all, much less advising them as to the possibility that their duties might be stricter than those of directors or cautioning that the business judgment rule may not apply to officer conduct in the same way it applies to directors. The paper also offers several reasons why lawyers should advise corporate officers as to their fiduciary duties. Doing so serves to highlight the key governance role played by officers, thereby partially re-directing corporate law\u27s customary and inappropriately exclusive focus on directors. The paper closes by describing a proposed procedure for assuring directors that legal counsel is regularly providing fiduciary duty advice to senior officers

Lie group analysis of a generalized Krichever-Novikov differential-difference equation

The symmetry algebra of the differential--difference equation $$\dot u_n = [P(u_n)u_{n+1}u_{n-1} + Q(u_n)(u_{n+1}+u_{n-1})+ R(u_n)]/(u_{n+1}-u_{n-1}),$$ where $P$, $Q$ and $R$ are arbitrary analytic functions is shown to have the dimension 1 \le \mbox{dim}L \le 5. When $P$, $Q$ and $R$ are specific second order polynomials in $u_n$ (depending on 6 constants) this is the integrable discretization of the Krichever--Novikov equation. We find 3 cases when the arbitrary functions are not polynomials and the symmetry algebra satisfies \mbox{dim}L=2. These cases are shown not to be integrable. The symmetry algebras are used to reduce the equations to purely difference ones. The symmetry group is also used to impose periodicity $u_{n+N}=u_n$ and thus to reduce the differential--difference equation to a system of $N$ coupled ordinary three points difference equations

Pregnant women voice their concerns and birth expectations during the COVID-19 pandemic in Italy.

Background In March 2020, COVID-19 was declared to be a pandemic. While data suggests that COVID-19 is not associated with significant adverse health outcomes for pregnant women and newborns, the psychological impact on pregnant women is likely to be high. Aim The aim was to explore the psychological impact of the COVID-19 pandemic on Italian pregnant women, especially regarding concerns and birth expectations. Methods A cross-sectional online survey of pregnant women in Italy was conducted. Responses were analysed for all women and segregated into two groups depending on previous experience of pregnancy loss. Analysis of open text responses examined expectations and concerns before and after the onset of the pandemic. Findings Two hundred pregnant women responded to the first wave of the survey. Most (n = 157, 78.5%) had other children and 100 (50.0%) had a previous history of perinatal loss. ‘Joy’ was the most prevalent emotion expressed before COVID-19 (126, 63.0% before vs 34, 17.0% after; p < 0.05); fear was the most prevalent after (15, 7.5% before vs 98, 49.0% after; p < 0.05). Positive constructs were prevalent before COVID-19, while negative ones were dominant after (p < 0.05). Across the country, women were concerned about COVID-19 and a history of psychological disorders was significantly associated with higher concerns (p < 0.05). A previous pregnancy loss did not influence women’s concerns. Conclusions Women’s expectations and concerns regarding childbirth changed significantly as a result of the COVID-19 pandemic in Italy. Women with a history of psychological disorders need particular attention as they seem to experience higher levels of concern

Aggression, Impulsivity and Suicidal Behavior in Depressive Disorders: A Comparison Study between New York City (US), Madrid (Spain) and Florence (Italy)

The association of aggression and impulsivity with suicidal behavior (SB) in depression may vary across countries. This study aimed (i) to compare aggression and impulsivity levels, measured with the Brown-Goodwin Scale (BGS) and the Barratt Impulsivity Scale (BIS), respectively, between New York City (NYC) (US), Madrid (Spain) and Florence (Italy) (ANOVA); and (ii) to investigate between-site differences in the association of aggression and impulsivity with previous SB (binary logistic regression). Aggression scores were higher in NYC, followed by Florence and Madrid. Impulsivity levels were higher in Florence than in Madrid or NYC. Aggression and impulsivity scores were higher in suicide attempters than in non-attempters in NYC and in Madrid. SB was associated with aggression in NYC (OR 1.12, 95% CI 1.07–1.16; p p = 0.032). Impulsivity was linked with SB in NYC (OR 1.01, 95% CI 1.00–1.02; p p < 0.001). The higher suicide rates in NYC, compared to Madrid or Florence, may be, in part, explained by these cross-cultural differences in the contribution of aggression-impulsivity to SB, which should be considered by future research on SB prevention

The methodology of investigation on red- and black-figured pottery of unknown provenance

This contribution is concerned with the archaeometric study of seven red- and black-figured potteries, kindly provided by the Carabinieri Corps for Protection of Cultural Heritage, Cosenza Unit (Calabria, Italy). The study was aimed to establish the authenticity of the archaeological artifacts and for this purpose an analytical approach, based on mineropetrographic and geochemical investigations, was applied. Petrographic analysis (OM), scanning electron microscopy (SEM) coupled with EDS microanalysis and X-ray diffraction (XRD) studies were carried out with the aim of identifying technological features, microstructure and to obtain information on the technological features of each sample. Finally, Fourier transform infrared spectroscopy (FT-IR) was used to detect possible surface coatings

Stability of the selfsimilar dynamics of a vortex filament

In this paper we continue our investigation about selfsimilar solutions of the vortex filament equation, also known as the binormal flow (BF) or the localized induction equation (LIE). Our main result is the stability of the selfsimilar dynamics of small pertubations of a given selfsimilar solution. The proof relies on finding precise asymptotics in space and time for the tangent and the normal vectors of the perturbations. A main ingredient in the proof is the control of the evolution of weighted norms for a cubic 1-D Schr\"odinger equation, connected to the binormal flow by Hasimoto's transform.Comment: revised version, 36 page

Constraints on anomalous Higgs boson couplings using production and decay information in the four-lepton final state

A search is performed for anomalous interactions of the recently discovered Higgs boson using matrix element techniques with the information from its decay to four leptons and from associated Higgs boson production with two quark jets in either vector boson fusion or associated production with a vector boson. The data were recorded by the CMS experiment at the LHC at a center-of-mass energy of and correspond to an integrated luminosity of . They are combined with the data collected at center-of-mass energies of 7 and , corresponding to integrated luminosities of 5.1 and , respectively. All observations are consistent with the expectations for the standard model Higgs boson

Search for new phenomena in final states with two opposite-charge, same-flavor leptons, jets, and missing transverse momentum in pp collisions at sqrt(s) = 13 TeV

Search results are presented for physics beyond the standard model in final states with two opposite-charge, same-flavor leptons, jets, and missing transverse momentum. The data sample corresponds to an integrated luminosity of 35.9 fb 121 of proton-proton collisions at s 1a=13 TeV collected with the CMS detector at the LHC in 2016. The analysis uses the invariant mass of the lepton pair, searching for a kinematic edge or a resonant-like excess compatible with the Z boson mass. The search for a kinematic edge targets production of particles sensitive to the strong force, while the resonance search targets both strongly and electroweakly produced new physics. The observed yields are consistent with the expectations from the standard model, and the results are interpreted in the context of simplified models of supersymmetry. In a gauge mediated supersymmetry breaking (GMSB) model of gluino pair production with decay chains including Z bosons, gluino masses up to 1500\u20131770 GeV are excluded at the 95% confidence level depending on the lightest neutralino mass. In a model of electroweak chargino-neutralino production, chargino masses as high as 610 GeV are excluded when the lightest neutralino is massless. In GMSB models of electroweak neutralino-neutralino production, neutralino masses up to 500-650 GeV are excluded depending on the decay mode assumed. Finally, in a model with bottom squark pair production and decay chains resulting in a kinematic edge in the dilepton invariant mass distribution, bottom squark masses up to 980\u20131200 GeV are excluded depending on the mass of the next-to-lightest neutralino