Broad Histogram Method for Continuous Systems: the XY-Model

We propose a way of implementing the Broad Histogram Monte Carlo method to systems with continuous degrees of freedom, and we apply these ideas to investigate the three-dimensional XY-model with periodic boundary conditions. We have found an excellent agreement between our method and traditional Metropolis results for the energy, the magnetization, the specific heat and the magnetic susceptibility on a very large temperature range. For the calculation of these quantities in the temperature range 0.7<T<4.7 our method took less CPU time than the Metropolis simulations for 16 temperature points in that temperature range. Furthermore, it calculates the whole temperature range 1.2<T<4.7 using only 2.2 times more computer effort than the Histogram Monte Carlo method for the range 2.1<T<2.2. Our way of treatment is general, it can also be applied to other systems with continuous degrees of freedom.Comment: 23 pages, 10 Postscript figures, to be published in Int. J. Mod. Phys.

Percepções de pacientes sobre catarata

OBJECTIVE: To identify in adult patients suffering from cataract the perceptions regarding the disease and its surgical treatment. MATERIALS AND METHODS: An exploratory survey was conducted among adult patients suffering from cataract and participating in a large-scale cataract management program at the University of São Paulo General Hospital in 2004. The interviews were conducted by research assistants previously trained to pose questions and record answers. RESULTS: The sample consisted of 170 men and women (43.5% and 56.5%, respectively), aged between 40 and 88 years. Of the 170 participants, 43.5% were from the State of São Paulo, 14.7% from the State of Bahia, 12.4% from the State of Minas Gerais, 5.9% from the State of Pernambuco, 1.8% from other countries, and the remaining 21.7% were from other Brazilian states. Of those who were actively working (n = 87), 43.7% had an occupational level corresponding to nonspecialized manual labor, 27.6% were in specialized manual labor jobs, 25.3% had routine nonmanual occupations, 1.1% supervised manual labor, and 2.3% had low-ranking supervision or inspection jobs over nonmanual occupations. Of those who were not actively working (n = 82), 53.6% were retired, 45.2% were housewives, and 1.2% were unemployed. Concerning conceptions about cataract, 79.0% referred to it as "a small skin fold that gradually covers the eye" and 32.4% mentioned, in addition, other conceptions. Concerning the cause, of the alternatives presented to them, 80% reported aging, 47.1% blamed "overusing the eyes in the workplace or at home", 7.1% believed they had cataract due to some kind of "spell." Of the associated answers, 94.1% referred to "blurred vision" in people suffering from cataract, 72.4% thought the person may become blind, and 66.5% believed that the patients suffering from cataract are depressed because they cannot see. Regarding surgery, 28.8% were afraid of undergoing surgery; of those, 16.3% cited with the fear of dying during surgery, 55.1% thought they might become blind, 40.8% believed the surgery would be painful, and 8.2% followed religious practices that do not permit surgery. CONCLUSION: Some misconceptions were identified, and the fear of blindness was the most mentioned reason for not seeking cataract surgery, which indicates the need for orientation.OBJETIVO: Identificar percepções de adultos portadores de catarata em relação à doença e ao tratamento cirúrgico. MATERIAIS E MÉTODOS: Foi realizada uma pesquisa exploratória entre pacientes adultos portadores de catarata presentes em mutirão em hospital universitário no ano de 2004. Auxiliares de pesquisa previamente treinados para formulação das questões e registros das respostas, encarregaram-se das entrevistas. RESULTADOS: A amostra foi composta por 170 sujeitos de ambos os sexos (43,5% do sexo masculino e 56,5% do sexo feminino) com idade entre 40 e 88 anos. Dos 170 participantes, 43,5% eram nascidos no estado de São Paulo, 14,7% na Bahia, 12,4% em Minas Gerais, 1,8% nasceram em outros paises e os demais sujeitos, em outros estados brasileiros.Da população ativa no mercado de trabalho (n=87), encontravam-se em nível de ocupação manual não especializada 43,7%; ocupação manual especializada 27,6%; ocupação de rotina não manual 25,3%; supervisão de trabalho manual 1,1%; posição baixa de supervisão ou inspeção , considerando ocupações não manuais,2,3 %. Entre a população inativa no mercado de trabalho (n=82), 53,6% eram aposentados, 45,2% donas de casa e 1,2% desempregados. Em relação a concepção sobre catarata, 79,0% referiram ser uma "pelezinha que vai cobrindo os olhos" e 32,4% além da "pelezinha", mencionaram outras concepções. Em relação a causa , entre as opções fornecidas, 80% relacionam a velhice; 47,1% "por usar muito as vistas no serviço ou em casa"; 7,1% acreditam que tem catarata devido a "mau olhado". Dentre as respostas associadas, 94,1% referiram que a "visão fica embaçada" na pessoa que tem catarata, 72,4% acham que a pessoa pode ficar cega e 66,5% acham que os portadores de catarata ficam com depressão por não enxergarem. Vinte e oito por cento tem medo de se submeter a cirurgia, desses, 16,3% atribuem ao fato de poderem morrer na cirurgia; 55,1% acham que podem ficar cego; 40,8% crêem que a cirurgia dói e 8,2% tem medo de operar pois a religião não permite. CONCLUSÃO: Foram evidenciados alguns conhecimentos incorretos, o medo de ficar cego se fez presente entre as razões para não operar a catarata, indicando necessidade de provimento de orientação

Study of the Fully Frustrated Clock Model using the Wang-Landau Algorithm

Monte Carlo simulations using the newly proposed Wang-Landau algorithm together with the broad histogram relation are performed to study the antiferromagnetic six-state clock model on the triangular lattice, which is fully frustrated. We confirm the existence of the magnetic ordering belonging to the Kosterlitz-Thouless (KT) type phase transition followed by the chiral ordering which occurs at slightly higher temperature. We also observe the lower temperature phase transition of KT type due to the discrete symmetry of the clock model. By using finite-size scaling analysis, the higher KT temperature $T_2$ and the chiral critical temperature $T_c$ are respectively estimated as $T_2=0.5154(8)$ and $T_c=0.5194(4)$. The results are in favor of the double transition scenario. The lower KT temperature is estimated as $T_1=0.496(2)$. Two decay exponents of KT transitions corresponding to higher and lower temperatures are respectively estimated as $\eta_2=0.25(1)$ and $\eta_1=0.13(1)$, which suggests that the exponents associated with the KT transitions are universal even for the frustrated model.Comment: 7 pages including 9 eps figures, RevTeX, to appear in J. Phys.

Quality assessment of systematic reviews regarding dental implant placement on diabetic patients : an overview of systematic reviews

Since implant placement on diabetic patients still is a controversial topic and systematic reviews are at the top of scientific evidence hierarchy, a thorough assessment of the methodological quality of these reviews must be performed to inform clinicians if their conclusions and recommendations can be followed on clinical practice. An overview of systematic reviews was performed with the purpose to assess the methodological quality of systematic reviews regarding dental implant placement on diabetic patients. In addition, we presented a synthesis of clinical outcomes about the focused theme. An online search was performed on MEDLINE via PubMed, EMBASE, DARE-Cochrane, Scopus, Web of Science, LILACS, and SIGLE via Open Grey. Searches were conducted from database inception to May 2018. Systematic review articles with or without meta-analysis about the placement of dental implants on diabetic patients were included. Exclusion criteria were: articles whose primary outcome was not the survival/success rate of dental implants on diabetic patients; studies that do not relate the survival/success rate of dental implants with diabetes; duplicated papers. Methodological quality assessment was performed with AMSTAR. A descriptive synthesis of clinical outcomes was performed. We identified 1.661 initial hits and eight articles were selected for overview (kappa=0.83; strong agreement). Six studies presented moderate methodological quality and two showed high methodological quality. Implant survival rate ranged from 31.8% to 100% and data from four meta-analysis showed that diabetes does not affect implant survival rate. On the other hand, data from two meta-analysis for marginal bone loss showed that diabetes statistically affects this outcome. Two of the eight included studies presented high methodological quality and their meta-analysis showed that implant placement on diabetic patients does not affect implant survival rate and statistically affects marginal bone loss. However, clinicians must be aware that marginal bone loss values were not clinically relevant and may not be safe to follow the conclusions and recommendations of these studies

Opioids, sex and gender

JUSTIFICATIVA E OBJETIVOS: Sexo é um fator importante na modulação da experiência dolorosa. Evidências significativas têm demonstrado que a experiência à dor difere entre homens e mulheres, bem como na resposta à ativação do sistema opioide e seus efeitos analgésicos. Há evidências que as mulheres têm menor limiar que os homens para alguns estímulos álgicos. Os neurotransmissores opioides e seus receptores estão centralmente envolvidos na resposta ao estresse, na supressão à dor e na ação dos analgésicos opioides. O objetivo deste estudo foi analisar a relação entre sexo, gênero e sistema opioide e discutir a relevância de um dos aspectos mais intrigantes da fisiologia da dor: a presença da diferença entre sexo e gênero, sistema opioide e as respostas da analgesia por opioides. CONTEÚDO: Uma revisão da literatura sobre opioides, sexo e gênero, cujo objetivo foi mostrar dados atuais sobre a experiência dolorosa entre homens e mulheres, a ativação opioide central e a resposta aos analgésicos opioides. CONCLUSÃO: Os dados disponíveis na literatura, e os trabalhos em andamento indicam que o sexo provavelmente seja responsável pelas diferenças à analgesia opioide em homens e mulheres, mas a direção e a magnitude destas diferenças dependem de variáveis que se interagem. Como fatores importantes que interagem na percepção dolorosa e na resposta analgésica opioide, devem ser levados em consideração os fatores socioculturais e biológicos, incluindo as variações hormonais em mulheres e a presença do hormônio masculino nos homens.BACKGROUND AND OBJECTIVES: Sex is a major factor for pain modulation. Significant evidences have shown that pain experience is different between men and women, as well as the response to opioid system activation and its analgesic effects. There are evidences that women have lower pain threshold compared to men. Opioid neurotransmitters and their receptors are centrally involved with stress response, pain suppression and opioids analgesic action. This study aimed to illustrate the relationship between sex, gender and the opioid system and to discuss the relevance of one of the most intriguing aspects of pain physiology: differences between sex and gender, opioid system and opioids analgesic response. CONTENTS: A literature review on opioids, sex and gender, aiming to show current data on pain experience between men and women, central opioid activation and response to opioids. CONCLUSION: Data in the literature and ongoing studies indicate that sex is probably responsible for differences in opioid analgesia between men and women, but the direction and magnitude of such differences depend on interacting variables. Socio-cultural and biological factors, including hormonal variations in women and the presence of male hormone in men are important factors interacting with pain perception and opioid analgesic response

Ethyl 2-[(carbamoyl­amino)­imino]­propano­ate hemihydrate

The title compound, C6H11N3O3·0.5H2O, has two independent mol­ecules and one mol­ecule of water in the asymmetric unit. The crystal packing is stabilized by inter­molecular N—H⋯N, O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds. These inter­actions form a two-dimensional array in the ab plane with a zigzag motif which has an angle close to 35° between the zigzag planes. The hydrogen bonding can be best described using the graph-set notation as N 1 = C(10)R 2 2(10)R 2 2(8) and N 2 = R 6 4(20)R 2 2(8)

Ethyl 2-[(carbamothioyl­amino)­imino]­propano­ate

The title compound, C6H11N3O2S, consists of a roughly planar mol­ecule (r.m.s deviation from planarity = 0.077 Å for the non-H atoms) and has the S atom in an anti position to the imine N atom. This N atom is the acceptor of a strongly bent inter­nal N—H⋯N hydrogen bond donated by the amino group. In the crystal, mol­ecules are arranged in undulating layers parallel to (010). The mol­ecules are linked via inter­molecular amino–carboxyl N—H⋯O hydrogen bonds, forming chains parallel to [001]. The chains are cross-linked by Ncarbazone—H⋯S and C—H⋯S inter­actions, forming infinite sheets