Failure of the work-Hamiltonian connection for free energy calculations

Extensions of statistical mechanics are routinely being used to infer free energies from the work performed over single-molecule nonequilibrium trajectories. A key element of this approach is the ubiquitous expression dW/dt=\partial H(x,t)/ \partial t which connects the microscopic work W performed by a time-dependent force on the coordinate x with the corresponding Hamiltonian H(x,t) at time t. Here we show that this connection, as pivotal as it is, cannot be used to estimate free energy changes. We discuss the implications of this result for single-molecule experiments and atomistic molecular simulations and point out possible avenues to overcome these limitations

Divergências morfológicas e de caracteristicas qualitativas nas variedades de uva Itália e Italia melhorada no Submédio São Francisco.

As variedades de uva Italia e Italia Melhorada são amplamente difundidas no Vale do Submédio São Francisco. Porém, não se sabe a origem da Italia Melhorada. O presente trabalho teve como objetivo comparar morfologicamente as variedades Italia e Italia Melhorada, a fim de constatar as semelhanças e divergências entre elas. Os trabalhos foram realizados na coleção de videira da Embrapa Semi-Árido, localizada na Estação Experimental de Mandacaru, Juazeiro-BA. As avaliações levaram em consideração caracteres morfológicos de folhas e frutos. Para as características de folhas, foram coletadas amostras de quatro plantas das regiões apical, mediana e basal, medindo-se os comprimentos das nervuras denominadas nervura mediana (L1); lateral superior (L2); lateral inferior (L3) e nervura peciolada (L4). Avaliaram-se também as características qualitativas tais como pilosidade, cor, forma do limbo e dos ?dentes?, e número de lóbulos. Em relação às características de frutos, avaliaram-se o comprimento e o diâmetro dos cachos e das bagas, em 10 frutos/planta, coletados em cinco plantas de vinhedos comerciais. Para análise estatística, utilizou-se o delineamento de blocos inteiramente casualizados, onde as plantas foram consideradas repetições. Realizaram-se a análise de variância e a comparação de médias pelo teste de Tukey ao nível de 5% de probabilidade. Os resultados revelaram diferenças significativas apenas em relação aos comprimentos das nervuras L1 nas folhas medianas e L4 nas folhas basais, em que a Italia Melhorada apresentou médias superiores (9,8 e 3,4 cm, respectivamente) às da Italia (7,6 e 2,7 cm, respectivamente). Para a morfologia do cacho, houve diferença significativa em relação ao comprimento do cacho, largura e comprimento das bagas em que a Italia Melhorada apresentou médias superiores (24,7; 30,43 e 25,54 cm, respectivamente) às da Italia (16,1; 26,38 e 23 cm, respectivamente). Nas avaliações referentes aos caracteres qualitativos, não foram observadas diferenças entre as duas variedades

On the Renormalizability of Noncommutative U(1) Gauge Theory - an Algebraic Approach

We investigate the quantum effects of the nonlocal gauge invariant operator $\frac{1}{{}{D}^{2}}{F}_{\mu \nu}\ast \frac{1}{{}{D}^{2}}{F}^{\mu \nu}$ in the noncommutative U(1) action and its consequences to the infrared sector of the theory. Nonlocal operators of such kind were proposed to solve the infrared problem of the noncommutative gauge theories evading the questions on the explicit breaking of the Lorentz invariance. More recently, a first step in the localization of this operator was accomplished by means of the introduction of an extra tensorial matter field, and the first loop analysis was carried out $(Eur.Phys.J.\textbf{C62}:433-443,2009)$. We will complete this localization avoiding the introduction of new degrees of freedom beyond those of the original action by using only BRST doublets. This will allow us to make a complete BRST algebraic study of the renormalizability of the theory, following Zwanziger's method of localization of nonlocal operators in QFT.Comment: standard Latex no figures, version2 accepted in J. Phys A: Math Theo

Perturbing Topological Field Theories

The abelian Chern-Simons theory is perturbed by introducing local gauge-invariant interaction terms depending on the curvature. The computation of the correlation function of two Wilson lines for two smooth closed nonintersecting curves is reported up to four loops and is shown to be unaffected by radiative corrections. This result ensures the stability of the linking number of the two curves with respect to the local perturbations which may be added to the Chern-Simons action.Comment: 13 pages, 5 figures, corrected some typo

Breastfeeding media coverage and beliefs during the COVID-19 pandemic in Mexico: implications for breastfeeding equity

Background: Because breastfeeding offers short- and long- term health benefits to mothers and children, breastfeeding promotion and support is a public health priority. Evidence shows that SARS-CoV-2 is not likely to be transmitted via breastmilk. Moreover, antibodies against SARS-CoV-2 are thought to be contained in breastmilk of mothers with history of COVID-19 infection or vaccination. WHO recommends direct breastfeeding as the preferred infant feeding option during the COVID-19 pandemic, even among women with COVID-19; but conflicting practices have been adopted, which could widen existing inequities in breastfeeding. This study aims to describe how information about breastfeeding was communicated in Mexican media during the pandemic and assess Mexican adults’ beliefs regarding breastfeeding among mothers infected with COVID-19. Methods: We conducted a retrospective content analysis of media coverage on breastfeeding in Mexico between March 1 and September 24, 2020, excluding advertisements. For the content analysis, we performed both a sentiment analysis and an analysis based on strengths, weaknesses, opportunities, and threats (SWOT) for breastfeeding promotion. Additionally, we conducted a descriptive analysis of nationally representative data on adults’ beliefs about breastfeeding from the July 2020 round of the ENCOVID-19 survey in Mexico and stratified the results by gender, age, and socioeconomic status. Results: A total of 1014 publications on breastfeeding were identified on the internet and television and in newspapers and magazines. Most information was published during World Breastfeeding Week, celebrated in August. The sentiment analysis showed that 57.2% of all information was classified as positive. The SWOT analysis indicated that most information focused on current actions, messages, policies, or programs that enable breastfeeding (i.e., strengths) or those not currently in place but that may enable breastfeeding (i.e., opportunities) for breastfeeding promotion. However, ENCOVID-19 survey results showed that 67.3% of adults living in households with children under 3 years of age believe that mothers with COVID-19 should not breastfeed, and 19.8% do not know whether these mothers should breastfeed. These beliefs showed differences both by gender and by socioeconomic status. Conclusions: While the Mexican government endorsed the recommendation on breastfeeding during the COVID-19 pandemic, communication was sporadic, inconstant and unequal across types of media. There was a widespread notion that mothers with COVID-19 should not breastfeed and due to differences on beliefs by socioeconomic status, health inequities could be exacerbated by increasing the risk of poorer breastfeeding practices and preventing vulnerable groups from reaping the short and long-term benefits of breastfeeding

An Algebraic Criterion for the Ultraviolet Finiteness of Quantum Field Theories

An algebraic criterion for the vanishing of the beta function for renormalizable quantum field theories is presented. Use is made of the descent equations following from the Wess-Zumino consistency condition. In some cases, these equations relate the fully quantized action to a local gauge invariant polynomial. The vanishing of the anomalous dimension of this polynomial enables us to establish a nonrenormalization theorem for the beta function $\beta_g$, stating that if the one-loop order contribution vanishes, then $\beta_g$ will vanish to all orders of perturbation theory. As a by-product, the special case in which $\beta_g$ is only of one-loop order, without further corrections, is also covered. The examples of the N=2,4 supersymmetric Yang-Mills theories are worked out in detail.Comment: 1+32 pages, LaTeX2e, typos correcte

A BRST Characterization of the Broken Phase Observables of the Confining Complex Theory

Some time ago we have introduced a route to provide confinement in the sense that particle excitations would appear from condensates of fields that do not have physical asymptotic states. We envisaged this mechanism in an asymmetric vacuum phase of a complex gauge field theory. More recently, we showed how to define a BRST operator to the broken phase of a generic spontaneous broken field theory. Our intention here is to apply these late concepts to the previous complex field theory in order to give a cohomological characterization of those condensed states as actual physical observables of this theory in its broken phase.Comment: 2 figures, 12 page