On-Site Potential Creates Complexity in Systems with Disordered Coupling

We calculate the average number of critical points N[over ¯] of the energy landscape of a many-body system with disordered two-body interactions and a weak on-site potential. We find that introducing a weak nonlinear on-site potential dramatically increases N[over ¯] to exponential in system size and give a complete picture of the organization of critical points. Our results extend solvable spin-glass models to physically more realistic models and are of relevance to glassy systems, nonlinear oscillator networks, and many-body interacting systems.

Dietary Changes and Anxiety during the Coronavirus Pandemic: Differences between the Sexes

The SARS-CoV-2 (COVID-19) pandemic has been associated with both increased anxiety, deterioration in diet and weight gain. These associations may differ by sex. The present report examines differences by sex in diet quality in order to determine whether associations between diet and psychological stress during the initial phase of the COVID-19 pandemic differed by sex. This online study is available internationally in seven languages. The Mediterranean Diet Score was used to measure diet quality, while the General Anxiety Disorder 7-point scale (GAD-7) was used to measure anxiety. Findings were compared by self-reported sex (male vs. female). A total of 3797 respondents provided informed consent and met eligibility criteria, of whom 526 women were omitted due to being pregnant or six months or less post-partum, or due to reproductive status not being reported. Thus, 3271 individuals are included in the present report, of whom 71.2% were women. The median age of women was 30 (interquartile range (IQR) = 16) years vs. 31 (IQR = 19) years, p = 0.079. The median diet quality score was 9 (IQ = 3) in both women and men (p = 0.75). Despite the overall similarity in diet score, several components of the score differed significantly by sex. Women reported consuming significantly more olive oil, daily servings of vegetables, and weekly servings of sweet baked goods. Men reported consuming significantly more sweetened/carbonated drinks, red meat, alcohol, legumes, and hummus/tahini. Women reported a GAD-7 score of 6 (IQR = 8), while men reported 3 (6), p < 0.001. An inverse association was detected between the Mediterranean diet score and the GAD-7 score in both women (rho = −0.166, p < 0.001) and men (rho = −0.154, p < 0.001), and the correlation coefficients did not differ by sex (p = 0.76). Mediterranean diet score and age both reduced the odds of elevated anxiety (GAD-7 ≥ 10), while female sex, deterioration of diet quality during the outbreak, unemployment, and completing the survey in English increased the odds of this outcome. During the COVID-19 lockdowns, overall diet quality did not differ by sex; however, some differences by sex in components of the total score were detected. Moderate to severe anxiety was positively associated with female sex and poorer diet quality even after controlling for age, employment status, and the language in which the survey was performed.

Multinational dietary changes and anxiety during the coronavirus pandemic-findings from Israel

BACKGROUND

Increased anxiety was frequently reported during the 2020 global COVID-19 pandemic. An association between anxiety and increased body weight has been documented. Identifying associations between diet quality and anxiety may facilitate the development of preventive dietary policy, particularly relevant since obesity appears to increase the risk of adverse COVID-19 outcomes. In this study we aim to examine associations between changes in diet pattern and body weight and anxiety levels during the COVID-19 pandemic among Israeli respondents to an international online survey.

METHODS

Conducted between March 30-April 252,020, this was cross-sectional, international and online study. The questionnaire was developed and tested in Hebrew and translated into six other languages: English, Arabic, Spanish, French, Italian, and Russian. The survey was conducted on a Google Survey platform, the link to which was posted on several social media platforms. Adults aged 18 or older who saw and responded to the link on a social media site comprised the study population.

RESULTS

Of the 3979 eligible respondents, 1895 indicated their current location as Israel. Most Israeli respondents completed the survey in Hebrew (83.2%) followed by Arabic (9.4%), though responses were recorded in all seven of the survey languages. The median age was 33 (IQ = 22) years, and 75.7% were female. Almost 60% indicated that their pre-pandemic diet was healthier than their current diet, and 25.2% indicated they had gained weight during the pandemic. The median Mediterranean diet score was 9 (IQ = 3). While the median General Anxiety Disorder (GAD-7) score was 5 (IQ = 8), only 37.3% of participants reported at least mild anxiety (a GAD-7 score of 5 or more), while 10.7% reported moderate anxiety or greater (a GAD-7 score of 10 or more). In a multivariate logistic regression model of at least mild anxiety, being male and completing the survey in Hebrew significantly reduced odds of at least mild anxiety, while a worsening of diet quality during the pandemic, weight gain, and isolation significantly increased odds of at least mild anxiety.

CONCLUSIONS

During the COVID pandemic, changes in nutrition quality and habits were associated with greater anxiety. These findings suggest the need for routine and continuous surveillance of the nutritional and psychological consequences of outbreaks as part of healthcare preparedness efforts. Organizations responsible for community-based health services (such as Israeli health plans) should adopt specific interventions to improve case finding and support individuals at increased risk of anxiety and declining nutrition status within primary healthcare settings. These interventions should include the provision of appropriate diagnostic instruments, training of medical staff, feedback to physicians and nurses, and raising awareness among the relevant patient population and their caregivers. Primary care physicians should refer people with high anxiety or substantial weight gain during the pandemic to appropriate mental health and dietetic treatment, as needed.

TRIAL REGISTRATION

NCT04353934 .

Gut microbiota determines the social behavior of mice and induces metabolic and inflammatory changes in their adipose tissue

The link between the gut microbiota and social behavior has been demonstrated, however the translational impact of a certain microbiota composition on stable behavioral patterns is yet to be elucidated. Here we employed an established social behavior mouse model of dominance (Dom) or submissiveness (Sub). A comprehensive 16S rRNA gene sequence analysis of Dom and Sub mice revealed a significantly different gut microbiota composition that clearly distinguishes between the two behavioral modes. Sub mice gut microbiota is significantly less diverse than that of Dom mice, and their taxa composition uniquely comprised the genera Mycoplasma and Anaeroplasma of the Tenericutes phylum, in addition to the Rikenellaceae and Clostridiaceae families. Conversely, the gut microbiota of Dom mice includes the genus Prevotella of the Bacteriodetes phylum, significantly less abundant in Sub mice. In addition, Sub mice show lower body weight from the age of 2 weeks and throughout their life span, accompanied with lower epididymis white adipose tissue (eWAT) mass and smaller adipocytes together with substantially elevated expression of inflammation and metabolic-related eWAT adipokines. Finally, fecal microbiota transplantation into germ-free mice show that Sub-transplanted mice acquired Sub microbiota and adopted their behavioral and physiological features, including depressive-like and anti-social behaviors alongside reduced eWAT mass, smaller adipocytes, and a Sub-like eWAT adipokine profile. Our findings demonstrate the critical role of the gut microbiome in determining dominance vs. submissiveness and suggest an association between gut microbiota, the eWAT metabolic and inflammatory profile, and the social behavior mode.

Mpemba effect in driven granular Maxwell gases

A Mpemba effect refers to the counterintuitive result that, when quenched to a low temperature, a system at higher temperature may equilibrate faster than one at intermediate temperatures. This effect has recently been demonstrated in driven granular gases, both for smooth as well as rough hard-sphere systems based on a perturbative analysis. In this paper, we consider the inelastic driven Maxwell gas, a simplified model for a granular gas, where the rate of collision is assumed to be independent of the relative velocity. Through an exact analysis, we determine the conditions under which the Mpemba effect is present in this model. For monodispersed gases, we show that the Mpemba effect is present only when the initial states are allowed to be nonstationary, while for bidispersed gases, it is present for some steady-state initial states. We also demonstrate the existence of the strong Mpemba effect for bidispersed Maxwell gas, wherein the system at higher temperature relaxes to a final steady state at an exponentially faster rate leading to smaller equilibration time.

Precooling Strategy Allows Exponentially Faster Heating

What is the fastest way to heat a system which is coupled to a temperature controlled oven? The intuitive answer is to use only the hottest temperature available. However, we show that often it is possible to achieve an exponentially faster heating protocol. Surprisingly, this protocol can have a precooling stage-cooling the system before heating it shortens the heating time significantly. To demonstrate such improvements in many-body systems, we developed a projection-based method with which such protocols can be found in large systems, as we demonstrate on the 2D antiferromagnet Ising model.

Rapid laser solver for the phase retrieval problem

Tailored physical systems were recently exploited to rapidly solve hard computational challenges, such as spin simulators, combinatorial optimization, and focusing through scattering media. Here, we address the phase retrieval problem where an object is reconstructed from its scattered intensity distribution. This is a key problem in many applications, ranging from x-ray imaging to astrophysics, and currently, it lacks efficient direct reconstruction methods: The widely used indirect iterative algorithms are inherently slow. We present an optical approach based on a digital degenerate cavity laser, whose most probable lasing mode rapidly and efficiently reconstructs the object. Our experimental results suggest that the gain competition between the many lasing modes acts as a highly parallel computer that could rapidly solve the phase retrieval problem. Our approach applies to most two-dimensional objects with known compact support, including complex-valued objects, and can be generalized to imaging through scattering media and other hard computational tasks.

Functional Foods in fad diets: A review

Background: Fad diets can be defined as any diet making claims that are unrealistic and not supported by evidence-based data. Having been developed since the early 19th century, fad diets promise drastic weight loss and/or other unsubstantiated health claims, often omitting entire food groups. Their popularity with the public makes them an important topic for nutritionists and clinicians, especially in the framework of the obesity epidemic. Additionally, it is conceivable that components of fad diets can indeed facilitate weight loss, even if the diet overall is without merit. The grapefruit diet, the cabbage soup diet, and the human chorionic gonadotropin (hCG) diet are among the most popular fad diets and are reviewed within this study not only in terms of the diet plan itself, but also in terms of possible and known weight loss and health benefits provided by the foods on which the diets are based. Bioflavonoids in grapefruit, including naringin, hesperidin, and bergamottin, may benefit glucose homeostasis. Cabbage contains lutein, zeaxanthin, kaempferol, quercetin, and apigenin, which have anti-inflammatory properties and improve both glucose homeostasis and fat metabolism. The hCG diet is frequently supplemented with non-hCG preparations, which often  contains African mango, which has been shown to enhance weight loss by an unspecified mechanism; astragalus root, which has antioxidant, anti-inflammatory, and peroxisome proliferator-activated receptor-gamma receptor agonistic properties; arginine, which stimulates lipolysis; glutamine, which has been shown to enhance weight loss, perhaps by altering the gut microbiome; carnitine, which appears to facilitate weight loss; B12, which improves insulin resistance; and niacin, which improves the dyslipidemia associated with overweight/obesity. Presently, high quality clinical trials suggest that fad diets reduce weight in the short term due to drastic caloric restriction rather than functional food properties. However, the proof of principle has been demonstrated, and clinical trials of the functional foods utilized in fad diets are much needed.Keywords: functional foods, Fad diet, weight loss, naringin, hesperidin, and bergamottin

Geometric Heat Engines Featuring Power that Grows with Efficiency

Thermodynamics places a limit on the efficiency of heat engines, but not on their output power or on how the power and efficiency change with the engine's cycle time. In this Letter, we develop a geometrical description of the power and efficiency as a function of the cycle time, applicable to an important class of heat engine models. This geometrical description is used to design engine protocols that attain both the maximal power and maximal efficiency at the fast driving limit. Furthermore, using this method, we also prove that no protocol can exactly attain the Carnot efficiency at nonzero power.

The effect of two iso-caloric meals containing equal amounts of fats with a different fat composition on the inflammatory and metabolic markers in apparently healthy volunteers

Background

Little is known about the time-course of the postprandial appearance of macronutrient-induced inflammatory response. Our aim was to investigate the postprandial inflammatory and metabolic response following high fat, high caloric popular meals in apparently healthy participants.

Methods

Fifty four apparently healthy normal weight volunteers (BMI of 25.9±0.9) were given two iso-caloric meals with similar amounts but different composition of fats: a meal high in monounsaturated fats (MUFA), and a meal high in saturated fat (SFA). Three main effects and the interactions between them were analyzed: the time (before and 2 and 4 hours following the meals), the meal (MUFA or SFA) and the gender.

Results

The effect of time from the meal on hs-CRP level was highly significant (p=0.004). The highest responses were observed 2 hours after the meal (p=0.002). A statistically significant interaction was found between the time and the meal (p≤0.0001), which reflects the higher increase in hs-CRP values 2 hours after the SFA meal, with no effect by the MUFA meal. The white blood cell counts were affected significantly by the time (p≤0.0001) however, other inflammatory markers (fibrinogen, IL-6, TNFα, ICAM and VICAM) were not. All the metabolic markers (insulin, glucose, HOMA-R, QUICKI and triglycerides) were affected by the time (p≤0.0001), with no interactions observed.

Conclusions

Metabolic and modest inflammatory changes occur within a few hours after the ingestion of a high SFA meal in apparently healthy adults.

Stress among healthcare students--a cross disciplinary perspective

BACKGROUND AND PURPOSES

Perceived stress (PS) among healthcare students worldwide is a recognized problem. To address the paucity of data about the actual degree of PS, this study aimed to: 1) evaluate and compare PS across three healthcare programs (Physical Therapy [PT], Communication Disorders [CD], and Nutrition Sciences [NS]) in one university; 2) evaluate changes in PS across study years; 3) identify the contribution of academic- and socio-demographic-related variables to PS; and 4) determine whether the Israeli students' PS levels differ from those of their peers in other countries.

METHODS

A cross-sectional survey was performed among all undergraduate PT, CD, and NS students from one university. Data were collected using anonymous questionnaires. Instruments included the Perceived Stress Scale 10 (PSS) and the Undergraduate Sources of Stress (USOS). ANOVA was used to evaluate the differences between the three programs, and regression analysis to evaluate the contribution of socio-demographic factors to PS and USOS.

RESULTS

A total of 312 students (PT--154; CD--92; NS--66) participated in the study. Mean PSS (range: 13.5-13.6) was similar in the three programs. The USOS academic factor was the most reported source of stress in all programs. Most socio-demographic variables were not related to either PS or USOS.

CONCLUSIONS

Students from PT, CD, and NS programs perceived similar levels of stress. The academic factor was perceived as the most important source of stress by students from the three departments, despite differences in the academic educational programs. Further studies are needed to generalize these results and enable a comparison between healthcare students and other students' stress perceptions.

Passive InP regenerator integrated on SOI for the support of broadband silicon modulators

Passive signal regeneration based on the Membrane InP Switch (MIPS) is demonstrated. Because of the high confinement of light in the active region of the MIPS, the device acts as a saturable absorber with a highly non-linear response. Using this effect, the extinction ratio (ER) of low-ER signals can be tripled and a receiver sensitivity enhancement of 4.5dB is demonstrated using an input signal at 1Gb/s with an ER of 2dB. Regenerator operation up to 5Gb/s is demonstrated and using a device simulator a strategy to reach higher bitrate operation is proposed.

Bias-free, low power and optically driven membrane InP switch on SOI for remotely configurable photonic packet switches

A small footprint integrated Membrane InP Switch (MIPS) on Silicon-On-Insulator (SOI) is demonstrated for use in all-optical packet switching. The device consists of an optically pumped III-V membrane waveguide of only 100 nm thick, coupled to the underlying SOI waveguide circuit. Because of its limited thickness, the optical confinement in the active layers is maximized, allowing for high extinction ratio of over 30 dB when applying a low power optical pump signal, over the entire C-band. The switch has 400/1300 ps on/off switching times and no measurable pattern dependence or switching related power penalties for a bitrate up to 40 Gb/s, using a switching power of only 2 dBm.

Vectorial phase retrieval for linear characterization of attosecond pulses

The waveforms of attosecond pulses produced by high-harmonic generation carry information on the electronic structure and dynamics in atomic and molecular systems. Current methods for the temporal characterization of such pulses have limited sensitivity and impose significant experimental complexity. We propose a new linear and all-optical method inspired by widely used multidimensional phase retrieval algorithms. Our new scheme is based on the spectral measurement of two attosecond sources and their interference. As an example, we focus on the case of spectral polarization measurements of attosecond pulses, relying on their most fundamental property-being well confined in time. We demonstrate this method numerically by reconstructing the temporal profiles of attosecond pulses generated from aligned CO(2) molecules.

Near-threshold high-order harmonic spectroscopy with aligned molecules

We study high-order harmonic generation in aligned molecules close to the ionization threshold. Two distinct contributions to the harmonic signal are observed, which show very different responses to molecular alignment and ellipticity of the driving field. We perform a classical electron trajectory analysis, taking into account the significant influence of the Coulomb potential on the strong-field-driven electron dynamics. The two contributions are related to primary ionization and excitation processes, offering a deeper understanding of the origin of high harmonics near the ionization threshold. This Letter shows that high-harmonic spectroscopy can be extended to the near-threshold spectral range, which is in general spectroscopically rich.

Enhanced 40 and 80 Gb/s wavelength conversion using a rectangular shaped optical filter for both red and blue spectral slicing

By using a tunable filter with tunability of both bandwidth and wavelength and a very sharp filter roll-off, considerable improvement of all optical Wavelength Conversion, based on Cross Gain and Phase Modulation effects in a Semiconductor Optical Amplifier and spectral slicing, is shown. At 40 Gb/s slicing of blue spectral components is shown to result in a small penalty of 0.7 dB, with a minimal eye broadening, and at 80 Gb/s the low demonstrated 0.5 dB penalty is a dramatic improvement over previously reported wavelength converters using the same principal. Additionally, we give for the first time quantitative results for the case of red spectral slicing at 40 Gb/s which we found to have only 0.5 dB penalty and a narrower time response, as anticipated by previously published theoretical papers. Numerical simulations for the dependence of the eye opening on the filter characteristics highlight the importance of the combination of a sharp filter roll-off and a broad passband.

Efficiency of cargo towing by a microswimmer

We study the properties of an arbitrary microswimmer towing a passive load through a viscous liquid. The simple close-form expression for the dragging efficiency of a microswimmer dragging a distant load is found, and the approximation for finite mutual proximity is derived. We show that, while the swimmer can be arbitrarily efficient, the dragging efficiency is always bounded from above. It is also demonstrated, that opposite to Purcell's assumption [E. M. Purcell, Proc. Natl. Acad. Sci. U.S.A. 94, 11307 (1997)], the hydrodynamic coupling can "help" the propeller to tow the load. We support our conclusions by rigorous numerical calculations for the rotary swimmer, towing a spherical cargo positioned at a finite distance.

Dissociated effects of physical activity and weight loss on fibrinogen concentrations and markers of red blood cell aggregation. Relevance for life style modification in atherothrombosis

It has been shown that weight loss and physical activity contribute to a better biorheological profile. Yet, the concentrations of fibrinogen are not always reduced following life style modification. We evaluated the inter-relations between fibrinogen's pro red cell aggregation potential and reduced inflammation and improved lipid profile as anti-aggregating forces in a group of 20 apparently healthy obese volunteers following 4 and 8 months of intensive life modification program which included diet and strenuous physical activity. A significant (p=0.005) weight loss (from a mean+/-SD of 121.4+/-20.9 to 98.0+/-21.3 kg) and decrease in body mass index (from 40.8+/-4.3 to 32.9+/-5.3 kg/m(2), p=0.005) was noted in fourteen individuals who completed the 8-month program. The concentrations of clottable fibrinogen rose from 318+/-96 to 387+/-72 mg/dl (p=0.012) while there was a significant reduction in the erythrocyte sedimentation rate (ESR) (from 19.0+/-12.6 to 10.8+/-7.5 mm/h, p=0.018), triglycerides (from 143+/-80 to 80+/-44 mg/dl, p=0.005), LDL cholesterol (from 128+/-34 to 103+/-17 mg/dl, p=0.005) and total cholesterol (from 211+/-40 to 171+/-17 mg/dl, p=0.007), as well as decrease in insulin concentration (from 36.1+/-21.3 to 20.6+/-8.0 microu/ml, p=0.01) and the insulin resistance index (HOMA-R, from 9.1+/-6.4 to 4.9+/-2.1 glu*ins/405, p=0.008). Despite a significant increment in the concentrations of clottable fibrinogen, a significant reduction was noted in the degree of red cell aggregation as measured by using a slide test and direct visualization of the aggregates. Our conclusion is that the pro-aggregating properties of fibrinogen following intense physical activity are probable counterbalanced by the anti-aggregatory properties of an improved lipid profile and an attenuated acute phase response.

Food preferences, body weight, and platelet-poor plasma serotonin and catecholamines

The possible relationship between body weight, food preferences, and plasma neurotransmitters was investigated in 96 healthy volunteers. The volunteers were divided into groups according to sex, body mass index, and food preferences. In all groups fasting platelet-poor plasma (PPP) norepinephrine and serotonin (5-HT) were examined. PPP-5-HT was low in obese individuals (mean +/- SD: 51.7 +/- 34.6 nmol/L) in comparison with lean individuals (94.31 +/- 85.2 nmol/L; P < 0.01), in lean male carbohydrate cravers (22.7 +/- 16.4 nmol/L) in comparison with protein cravers (132.9 +/- 80.6 nmol/L; P < 0.005) and noncravers (64.7 +/- 51.7 nmol/L; P < 0.05), and in obese male carbohydrate cravers (34 +/- 22.7 nmol/L) in comparison with obese male protein cravers (98.8 +/- 28.4 nmol/L; P < 0.001). In conclusion, PPP-5-HT might be seen as a peripheral indicator of processes linked with food consumption and food preferences.

The influence of meal composition on plasma serotonin and norepinephrine concentrations

Reports concerning changes in plasma neurotransmitter values that result from dietary manipulations have not been published so far. The influence of various meal compositions on platelet-poor plasma (PPP) serotonin (5-HT) and norepinephrine (NE) levels was investigated. Healthy volunteers were subjected to three test meals: a carbohydrate-rich meal (86% carbohydrates), a protein-rich meal (70% protein), and a fat-rich meal (92% fat). After a carbohydrate-rich meal, PPP 5-HT values increased significantly (4.47-fold, P less than .02), whereas a smaller increase (1.66-fold, P = NS) was observed after a fat-rich meal. These effects on PPP 5-HT values could be correlated with insulin plasma levels. A protein-rich meal significantly reduced (P = 0.0011) PPP 5-HT to 28% of initial values, despite an increase in plasma insulin levels. This study has shown that (1) changes in meal compositions influence PPP 5-HT and, to a lesser extent, NE values; (2) the resulting changes in PPP 5-HT levels parallel those reported for brain neurotransmitters; and (3) these results seem to indicate that PPP 5-HT levels may be a model for brain synthesis and release of 5-HT.