Fermion- and spin-counting in strongly correlated systems in and out of thermal equilibrium

Atom counting theory can be used to study the role of thermal noise in quantum phase transitions and to monitor the dynamics of a quantum system. We illustrate this for a strongly correlated fermionic system, which is equivalent to an anisotropic quantum XY chain in a transverse field, and can be realized with cold fermionic atoms in an optical lattice. We analyze the counting statistics across the phase diagram in the presence of thermal fluctuations, and during its thermalization when the system is coupled to a heat bath. At zero temperature, the quantum phase transition is reflected in the cumulants of the counting distribution. We find that the signatures of the crossover remain visible at low temperature and are obscured with increasing thermal fluctuations. We find that the same quantities may be used to scan the dynamics during the thermalization of the system.Comment: 10 pages, 7 figure

How Best (Not) to Address the Ukraine Crisis

Russia's invasion of Ukraine has disrupted global wheat, corn, and other markets. Given relatively low global stocks for major staple foodstuffs, many analysts predict that food insecurity will increase among poor households in low-income countries. Understandably, many world leaders, including the Biden administration, are concerned about how to best address a potential global hunger crisis. However, in the rush to "do something," leaders need to consider the most efficient policies to address the crisis and avoid ill-considered policies that may do little to address the actual problems and could result in unintended consequences that may linger well past the crisis itself.The most effective way of addressing global food supply concerns would be an immediate end to the war and rebuilding critical infrastructures such as rail lines, storage facilities, and port facilities to allow Ukraine's agricultural sector access to global markets. To that end, the UN secretary general's efforts to end the blockade of Ukraine grain shipping and support the establishment of a blue corridor by sea or a green corridor overland to move foodstuffs from Ukraine should be supported. Unfortunately, the likelihood of a quick end to the war looks increasingly faint, and Russia has given no signs that it would consider granting safe passage of Ukraine food exports through the Black Sea.The Biden administration has recently put forward a set of proposals aimed at increasing US agricultural production, lowering fertilizer costs, and providing humanitarian food aid to those hurt by the sharp increase in agricultural prices. Here we consider these proposals and other questionable policies such as opening the Conservation Reserve Program (CRP) and conclude by discussing policies that could provide more immediate relief by addressing and mitigating constraints in the vegetable oil market

Effective radii of deuteron induced reactions

The continuum-discretized coupled-channels method (CDCC) for exclusive reactions and the eikonal reaction theory (ERT) as an extension of CDCC to inclusive reactions are applied to deuteron induced reactions. The CDCC result reproduces experimental data on the reaction cross section for $d+^{58}$Ni scattering at 200 MeV/nucleon and ERT does data on the neutron-stripping cross section for inclusive $^7$Li$(d,n)$ reaction at 40 MeV. For deuteron induced reactions at 200 MeV/nucleon, target-dependence of the reaction, elastic-breakup, nucleon-stripping, nucleon-removal, complete- and incomplete-fusion cross sections is clearly explained by simple formulae. Accuracy of the Glauber model is also investigated.Comment: 11 pages, 11 figures, 2 table

Nuclear transparencies for nucleons, knocked-out under various semi-inclusive conditions

Using hadron dynamics we calculate nuclear transparencies for protons, knocked-out in high-$Q^2$, semi-inclusive reactions. Predicted transparencies are, roughly half a standard deviation above the NE18 data. The latter contain the effects of binned proton missing momenta and mass, and of finite detector acceptances. In order to test sensitivity we compare computed transparencies without restrictions and the same with maximal cuts for missing momenta and the electron energy loss. We find hardly any variation, enabling a meaningful comparison with data and predictions based on hadron dynamics. Should discrepancies persist in high-statistics data, the above may with greater confidence be attributed to exotic components in the description of the outgoing proton.Comment: 13 pages + 3 figsin appended PS file, report # WIS-94/43/Oct-P

Low energy onset of nuclear shadowing in photoabsorption

The early onset of nuclear shadowing in photoabsorption at low photon energies has recently been interpreted as a possible signature of a decrease of the rho meson mass in nuclei. We show that one can understand this early onset within simple Glauber theory if one takes the negative real part of the rho N scattering amplitudes into account, corresponding to a higher effective mass of the rho meson in nuclear medium.Comment: REVTEX, 9 pages, including 4 eps figure

Optical realization of a quantum beam splitter

We show how the quantum process of splitting light may be modelled in classical optics. A second result is the possibility to engineer specific forms of a classical field.Comment: 5 page

Aspects of psychiatric care for obese patients under bariatric treatment: a review

CONTEXTO: Nas últimas décadas, diversos estudos longitudinais têm demonstrado a eficácia da cirurgia bariátrica no controle de peso em longo prazo e na redução da mortalidade resultante de complicações clínicas associadas à obesidade. Contudo, os estudos também revelam aumento significativo da mortalidade devida a suicídio e comportamento impulsivo, por razões largamente desconhecidas, o que demonstra a escassez de informações relativas ao manejo clínico de pacientes bariátricos. O presente estudo tem como objetivo sintetizar o estado atual de conhecimentos referentes ao acompanhamento psiquiátrico de pacientes bariátricos. MÉTODO: Revisão seletiva da literatura envolvendo artigos indexados no Medline e PubMed até junho de 2010, utilizando-se os termos: "bariatric surgery", "psychiatry", "binge eating", "follow-up" e "outcome". RESULTADOS: Há relativo consenso na literatura de que não haja contraindicação psiquiátrica absoluta para a cirurgia bariátrica, embora a avaliação pré-operatória seja de extrema importância para o diagnóstico e tratamento de eventuais transtornos psiquiátricos, objetivando assegurar aderência ao tratamento multidisciplinar, melhor qualidade de vida e, possivelmente, melhor prognóstico pós-cirúrgico. Entre os transtornos mais prevalentes nessa população, encontra-se o transtorno da compulsão alimentar periódica (TCAP), que está relacionado com menor perda ponderal e pior qualidade de vida, especialmente quando presente no pós-operatório. No acompanhamento pós-operatório, também se deve atentar para o surgimento de sintomas impulsivos, incluindo abuso de álcool e outras substâncias. CONCLUSÃO: Diversos estudos indicam elevada prevalência de transtornos mentais e alterações psicopatológicas na população de pacientes bariátricos. Embora a maioria dos pacientes apresente adequado controle ponderal e melhora na qualidade de vida em médio e longo prazo, alguns pacientes desenvolvem alterações relativas ao comportamento alimentar, abuso de álcool e outras substâncias e complicações associadas a comportamento impulsivo, o que remete a hipóteses etiológicas que vão desde modelos neuroquímicos até teorias psicossociais. Por todas essas razões, é de fundamental importância que os profissionais de saúde mental integrem as equipes que avaliam e acompanham os pacientes bariátricos.BACKGROUND: In recent decades, several longitudinal studies show the efficacy of bariatric surgery on long-term weight control and reductions in mortality due to clinical complications associated with obesity. However, studies also show significantly increased mortality due to suicide and impulsive behavior, for reasons largely unknown, which demonstrates the paucity of information concerning the clinical management of bariatric patients. This study aims to synthesize the current state of knowledge regarding the psychiatric care of bariatric patients. METHOD: A selective review of literature involving articles indexed on Medline and PubMed up to June 2010, using the terms: "bariatric surgery", "psychiatry", "binge eating", "follow-up", and "outcome". RESULTS: The literature is somehow consensual in which there is no absolute psychiatric contraindication for bariatric surgery, although the preoperative evaluation is of extreme importance for the diagnosis and treatment of any psychiatric disorder, to assure adherence to the multidisciplinary approach, improved quality of life and possibly a better prognosis after surgery. Among the most prevalent disorders in this population is the binge-eating disorder (BED), which is associated with lower weight loss and poor quality of life, especially when present in the postoperative period. In the postoperative follow-up one should also be alert to the emergence of impulsive symptoms, including abuse of alcohol and other substances. DISCUSSION: Several studies indicate high prevalence of mental disorders and psychopathology in the population of bariatric patients. Although most patients experience adequate weight control and improved quality of life in the medium and long term, some patients develop abnormal behavior relating to dysfunctional eating patterns, abuse of alcohol and other substances, and complications associated with impulsive behavior, which suggests etiological hypotheses involving from neurochemistry to psychosocial theories. For all these reasons, it is of fundamental importance that mental health professionals to integrate the teams that evaluate and monitor the bariatric patients

Quantum interference by two temporally distinguishable pulses

We report a two-photon interference effect, in which the entangled photon pairs are generated from two laser pulses well-separated in time. In a single pump pulse case, interference effects did not occur in our experimental scheme. However, by introducing a second pump pulse delayed in time, quantum interference was then observed. The visibility of the interference fringes shows dependence on the delay time between two laser pulses. The results are explained in terms of indistinguishability of biphoton amplitudes which originated from two temporally separated laser pulses.Comment: two-column, 4pages, submitted to PRA, minor change

Coherent analysis of quantum optical sideband modes

We demonstrate a device that allows for the coherent analysis of a pair of optical frequency sidebands in an arbitrary basis. We show that our device is quantum noise limited and hence applications for this scheme may be found in discrete and continuous variable optical quantum information experiments.Comment: 3 pages, 3 figures, submitted to Optics Letter

Observation of a Cooperative Radiation Force in the Presence of Disorder

Cooperative scattering of light by an extended object such as an atomic ensemble or a dielectric sphere is fundamentally different from scattering from many point-like scatterers such as single atoms. Homogeneous distributions tend to scatter cooperatively, whereas fluctuations of the density distribution increase the disorder and suppress cooperativity. In an atomic cloud, the amount of disorder can be tuned via the optical thickness, and its role can be studied via the radiation force exerted by the light on the atomic cloud. Monitoring cold $^{87}\text{Rb}$ atoms released from a magneto-optical trap, we present the first experimental signatures of radiation force reduction due to cooperative scattering. The results are in agreement with an analytical expression interpolating between the disorder and the cooperativity-dominated regimes