The critical current of disordered superconductors near 0 K.

An increasing current through a superconductor can result in a discontinuous increase in the differential resistance at the critical current. This critical current is typically associated either with breaking of Cooper-pairs or with the onset of collective motion of vortices. Here we measure the current-voltage characteristics of superconducting films at low temperatures and high magnetic fields. Using heat-balance considerations we demonstrate that the current-voltage characteristics are well explained by electron overheating enhanced by the thermal decoupling of the electrons from the host phonons. By solving the heat-balance equation we are able to accurately predict the critical currents in a variety of experimental conditions. The heat-balance approach is universal and applies to diverse situations from critical currents to climate change. One disadvantage of the universality of this approach is its insensitivity to the details of the system, which limits our ability to draw conclusions regarding the initial departure from equilibrium.

Sensitivity of the superconducting state in thin films.

For more than two decades, there have been reports on an unexpected metallic state separating the established superconducting and insulating phases of thin-film superconductors. To date, no theoretical explanation has been able to fully capture the existence of such a state for the large variety of superconductors exhibiting it. Here, we show that for two very different thin-film superconductors, amorphous indium oxide and a single crystal of 2H-NbSe2, this metallic state can be eliminated by adequately filtering external radiation. Our results show that the appearance of temperature-independent, metallic-like transport at low temperatures is sufficiently described by the extreme sensitivity of these superconducting films to external perturbations. We relate this sensitivity to the theoretical observation that, in two dimensions, superconductivity is only marginally stable.

Absence of Cyclotron Resonance in the Anomalous Metallic Phase in InO_{x}.

It is observed that many thin superconducting films with not too high disorder level (generally R_{N}/□<2000 Ω) placed in magnetic field show an anomalous metallic phase where the resistance is low but still finite as temperature goes to zero. Here we report in weakly disordered amorphous InO_{x} thin films that this anomalous metal phase possesses no cyclotron resonance and hence non-Drude electrodynamics. The absence of a finite frequency resonant mode can be associated with a vanishing downstream component of the vortex current parallel to the supercurrent and an emergent particle-hole symmetry of this metal, which establishes its non-Fermi-liquid character.

Instability of Insulators near Quantum Phase Transitions.

Thin films of amorphous indium oxide undergo a magnetic field driven superconducting to insulator quantum phase transition. In the insulating phase, the current-voltage characteristics show large current discontinuities due to overheating of electrons. We show that the onset voltage for the discontinuities vanishes as we approach the quantum critical point. As a result, the insulating phase becomes unstable with respect to any applied voltage making it, at least experimentally, immeasurable. We emphasize that unlike previous reports of the absence of linear response near quantum phase transitions, in our system, the departure from equilibrium is discontinuous. Because the conditions for these discontinuities are satisfied in most insulators at low temperatures, and due to the decay of all characteristic energy scales near quantum phase transitions, we believe that this instability is general and should occur in various systems while approaching their quantum critical point. Accounting for this instability is crucial for determining the critical behavior of systems near the transition.

Differences in homeostatic model assessment (HOMA) values and insulin levels after vitamin D supplementation in healthy men: a double-blind randomized controlled trial.

Vitamin D is thought to play a role in glucose metabolism. The aim of the present study was to determine the effect of vitamin D supplementation on markers of insulin sensitivity and inflammation in men without diabetes with vitamin D deficiency/insufficiency. In this 1-year double-blind randomized controlled trial, 130 men aged 20-65 years (mean age 47.52 ± 11.84 years) with serum 25-hydroxyvitamin D levels <50 nmol/l (mean 38.89 ± 8.64 nmol/l) were randomized to treatment (100 000 IU vitamin D bimonthly) or placebo. Anthropometric measurements, demographic questionnaires, and blood indices (fasting glucose, insulin, high-sensitivity C-reactive protein, lipids) were collected and repeated after 6 and 12 months. The compliance rate was 98.5%. Multivariate models, adjusted for baseline levels, age, body mass index, sun exposure, physical activity and LDL, showed significant differences in insulin and homeostatic model assessment of insulin resistance (HOMA-IR) values between groups. Levels of insulin and HOMA-IR values remained steady during the study period in the treatment group but increased by 16% in the control group (p = 0.038 and p = 0.048, respectively). Vitamin D supplementation administered for 12 months in healthy men maintained insulin levels and HOMA-IR values relative to the increase in the control group. Further studies are needed to establish the long-term effect of vitamin D supplementation on the risk of diabetes.

Nonequilibrium Second-Order Phase Transition in a Cooper-Pair Insulator.

In certain disordered superconductors, upon increasing the magnetic field, superconductivity terminates with a direct transition into an insulating phase. This phase is comprised of localized Cooper pairs and is termed a Cooper-pair insulator. The current-voltage characteristics measured in this insulating phase are highly nonlinear and, at low temperatures, exhibit abrupt current jumps. Increasing the temperature diminishes the jumps until the current-voltage characteristics become continuous. We show that a direct correspondence exists between our system and systems that undergo an equilibrium, second-order, phase transition. We illustrate this correspondence by comparing our results to the van der Waals equation of state for the liquid-gas mixture. We use the similarities to identify a critical point where an out of equilibrium second-order-like phase transition occurs in our system. Approaching the critical point, we find a power-law behavior with critical exponents that characterizes the transition.

Evidence for a Finite-Temperature Insulator.

In superconductors the zero-resistance current-flow is protected from dissipation at finite temperatures (T) by virtue of the short-circuit condition maintained by the electrons that remain in the condensed state. The recently suggested finite-T insulator and the "superinsulating" phase are different because any residual mechanism of conduction will eventually become dominant as the finite-T insulator sets-in. If the residual conduction is small it may be possible to observe the transition to these intriguing states. We show that the conductivity of the high magnetic-field insulator terminating superconductivity in amorphous indium-oxide exhibits an abrupt drop, and seem to approach a zero conductance at T < 0.04 K. We discuss our results in the light of theories that lead to a finite-T insulator.

Mediterranean diet and functional indicators among older adults in non-Mediterranean and Mediterranean countries.

BACKGROUND/OBJECTIVES: The Mediterranean diet (MEDDIET) has been shown to be related to longevity. This study aimed to determine the association between adherence to MEDDIET and physical function of older adults in the United-States and Israel. METHODS: Data from the US National Health and Nutrition Survey (NHANES) 1999-2002 and from the Israeli National Health and Nutrition Survey (MABAT ZAHAV) 2005-2006 were used. Participants with nutritional and functional data were included. Adherence to the MEDDIET was assessed by a 9-unit score (MDS). RESULTS: Among 2791 NHANES and 1786 MABAT ZAHAV participants, mean age=71.2 y and 74.9 y, 20% and 27% had low MDS (0-2), 66% and 62% had a medium score (3-5), and 14% and 11% had a high score (6-9), respectively. Higher MDS was associated with higher education and better lifestyle behaviors. Cognitive and physical functions were significantly better in NHANES and MABAT ZAHAV among the highest MDS. In NHANES, MDS (high vs. low) was associated with faster walking speed after adjusting for confounders in a logistic regression model [Odds Ratio (OR)=0.71, P=0.034, Cl 95% 0.511-0.974]. When cognitive function was added, the association was attenuated (OR=0.75, P=0.093, Cl 95% 0.540-1.049). In MABAT ZAHAV, in a logistic regression model adjusted among other to cognitive function, MDS (high vs. low) was associated with fewer disabilities (OR=0.51, P=0.029, Cl 95% 0.276-0.934). CONCLUSIONS: Adherence to the MEDDIET is associated with better health characteristics and better functioning. Further cohort and intervention studies may shed light on temporal and causal relationships between MEDDIET and these parameters.

Identifying the threshold for vitamin D insufficiency in relation to cardiometabolic markers.

BACKGROUND AND AIMS: To determine the association between vitamin D status and cardiometabolic indicators, and to determine the vitamin threshold that affects these parameters. METHODS AND RESULTS: High-tech employees were recruited from a periodic occupational health examination clinic and via the study's website. Diastolic and systolic blood pressure (DBP, SBP), body mass index (BMI), and waist circumference were measured. Serum concentrations of 25(OH)D, fasting plasma insulin (FPI), fasting plasma glucose (FPG), triglycerides (TG), and high sensitive C-Reactive Protein (hs-CRP) were measured in fasting blood samples. Of the 400 men who agreed to participate, 358 (90%) completed the study. Mean age was 48.8 ± 10.2 y, BMI 27.0 ± 3.8 k/m(2), serum 25(OH)D 22.1 ± 7.9 ng/l. Deficiency (defined as serum 25(OH)D < 12 ng/ml) was observed among 10.6%, 29.9% were insufficient (12 < 25(OH)D < 20 ng/ml), and 59.5% had sufficient levels (25(OH)D > 20 ng/ml). BMI, waist circumference, FPI, HOMA-IR, TG, hs-CRP levels, DBP, and SBP were negatively associated with serum 25(OH)D. A curved linear association was found with insulin and HOMA-IR with a significant spline knot at 11 ng/ml. For hs-CRP a spline knot at 14 ng/ml was observed. TG, SBP, and DBP exhibited linear associations with 25(OH)D. CONCLUSIONS: Vitamin D status is related to cardiometabolic indicators in healthy men. We suggest a 25(OH)D threshold of 11-14 ng/ml for these outcomes. Future studies are required to address temporal relationships and the impact of vitamin D supplementation.

Little-Parks oscillations in an insulator.

We present the results of a magnetoresistance study of the disorder-induced superconductor-insulator transition in an amorphous indium-oxide thin film patterned by a nanoscale periodic array of holes. We observed Little-Parks-like oscillations over our entire range of disorder spanning the transition. The period of oscillations was unchanged and corresponded to the superconducting flux quantum in the superconducting as well as in the insulating phases. Our results provide direct evidence for electron pairing in the insulator bordering with superconductivity.

Measurement of a superconducting energy gap in a homogeneously amorphous insulator.

We present tunneling spectroscopy measurements that directly reveal the existence of a superconducting gap in the insulating state of homogenously disordered amorphous indium oxide films. Two films on both sides of the disorder induced superconductor to insulator transition show the same energy gap scale. This energy gap persists up to relatively high magnetic fields and is observed across the magnetoresistance peak typical of disordered superconductors. The results provide useful information for understanding the nature of the insulating state in the disorder induced superconductor to insulator transition.

Coherent quantum phase slip.

A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology.

Maternal weight misperceptions and smoking are associated with overweight and obesity in low SES preschoolers.

OBJECTIVES: To identify modifiable risk factors for obesity among low socioeconomic status (LSES) children. METHODS: Cross-sectional data were obtained from 238 4-7-year-old children and 224 mothers from LSES preschools. Anthropometric measurements were obtained; mothers were interviewed about sociodemographic characteristics, health behaviors, perceptions and beliefs. RESULTS: The combined prevalence of overweight and obesity (OWOB) among children was 29.8% based on the new World Health Organization (WHO) growth standard. Prevalence of OWOB (body mass index ≥25) among mothers was 51.8%. Mean age, sleeping hours, gender distribution and poverty level were similar between normal and OWOB children. Over 82% of mothers underestimated their child's weight status. Of the 62 OWOB children, 74.2% were perceived by their mothers as having 'normal weight' (NW) and 8% were perceived as 'thin'. Mothers perceived 67 out of 158 NW children (42.4%) as 'thin' (P<0.001). Mediation analysis indicated that 10% of the effect of maternal underestimation on child's OWOB may be mediated through child's daily sedentary hours (P=0.06). In a multivariable logistic-regression analysis controlling for maternal obesity, knowledge regarding breakfast's importance and child's daily sedentary hours, maternal underestimation of the child's weight status (odds ratio=7.33; 95% confidence interval (CI):2.41-22.37; P<0.0001) and parental smoking (odds ratio=3.25; 95% CI: 1.26-8.40; P=0.015) were the only significant factors associated with OWOB in LSES children. CONCLUSIONS: Maternal perception of child's weight status and parental smoking are associated with childhood OWOB among LSES children. These parameters can help identify children at risk for obesity. Maternal perception may be amenable to intervention.

Intensive dietary intervention by a dietitian as a case manager among community dwelling older adults: the EDIT study.

BACKGROUND: Clinical trials that have assessed the best approach for treating under-nutrition in old age are scarce. OBJECTIVE: To determine the impact of an intensive nutritional intervention program led by a dietitian on the health and nutritional status of malnourished community dwelling older adults. METHODS: Sixty-eight eligible participants (age<75) were randomly assigned to a Dietetic Intervention Treatment (DIT), an intensive nutritional intervention led by a dietitian, or a Medical Treatment (MT), a physician-led standard care group, with an educational booklet regarding dietary requirements and recommendations for older adults. An additional 59 eligible participants who were unable to participate in the randomization were included as a non-randomized "untreated nutrition" group (UNG). RESULTS: Over the 6-month follow-up, the DIT group showed significant improvement in cognitive function (from 25.8±4.5 to 26.8±4, p=0.04), and depression score (from 7.3±3.9 to 5.4±3.9, p=0.04) compared with the change in the other 2 groups. The DIT group showed a significant improvement in intake of carbohydrates (+15% vs. +1% in the MT and +3% in the UNG), protein (+8% vs. +2% in the MT and -3% in the UNG), vitamin B6 (+20% vs. +7% in the MT and +8% in the UNG), and vitamin B1 (+22% vs. +11% in the MT and 0% in the UNG). The DIT group had a significantly lower cost of physician visits than the other 2 groups ($172.1±232.0 vs. $417.2±368.0 in the MT and $428.1±382.3 in the UNG, p=0.005). CONCLUSION: Intensive dietary intervention was moderately effective in lowering cost of services used and improving medical and nutritional status among community dwelling older adults.

Probiotics improve bowel movements in hospitalized elderly patients--the PROAGE study.

OBJECTIVE: To determine the impact of probiotics on the prevention of problems with bowel movements malnutrition and infection. DESIGN: A randomized, double-blind, placebo-controlled trial. SETTING: Peripheral Geriatric Hospital. PARTICIPANTS: 243 elderly patients age ≥ 65 y who were hospitalized in a Geriatric Orthopedic Rehabilitation Department. INTERVENTION: Participants were randomized into treatment or control groups (daily probiotics or placebo for 45 consecutive days, respectively). MEASUREMENTS: The main outcomes were: number of days of constipation or diarrhea and the number of days of laxative use. Secondary measures were nutritional status and blood measurements. RESULTS: Of 599 patients admitted to the Geriatric Rehabilitation ward, 345 were eligible and agreed to participate. During a 7-day pre-trial period, 102 patients dropped out (45 and 57 in the probiotic and placebo groups respectively). Out of the 243 patients who entered the study, 28 dropped out during the study (11.5%), leaving 215 patients. Throughout the 45 days of follow-up, the incidence of diarrhea was significantly lower among the study group (HR=0.42, p=0.04) with a more pronounced difference among participants aged ≥ 80 y (HR=0.32, p=0.026). Laxative use (as an indicator of constipation severity) was significantly lower in the study group compared with the control group (HR=0.74, p=0.032). Serum albumin, prealbumin and protein increased significantly more in the treatment group compared with the control group among participants age ≥ 80 y (P=0.047, p=0.07, p=0.03 respectively) but not in the younger age group. CONCLUSION: We showed that probiotic supplements may have a positive effect on bowel movements among orthopedic rehabilitation elderly patients.

Depressive symptoms are associated with food insufficiency and nutritional deficiencies in poor community-dwelling elderly people.

UNLABELLED: Depression is associated with nutritional deterioration in older persons and is highly prevalent among people of low socioeconomic status (LSES). OBJECTIVES: To determine the prevalence of depressive symptoms and food insufficiency, and to examine the relationship between dietary intake, food insufficiency and depression, in LSES community dwelling elderly. DESIGN: Cross-sectional study. SETTING: Lod, a town in the central Israel. PARTICIPANTS: Community-dwelling welfare recipients aged 60 to 92. MEASUREMENTS: Depression was assessed by 15-item Geriatric Depression Scale (GDS-short version), using a score ≥ 10 as the cut off point for clinically important depressive symptoms. Dietary intake was evaluated using a 24-hour dietary recall. Food insufficiency was defined by participants reporting that they did not have enough food to eat " sometimes " or " often " . RESULTS: This study reports on 112 persons aged 60 years and above (27.1% men). The prevalence of depression in this population was 47%; 25% of the study sample was classified as " food insufficient " . Macronutrients intake was similar for depressed and non-depressed persons, except for polyunsaturated fats which was lower among the depressed group (7.9 ± 4.9 vs.11.0 ± 7.5 g/day in the non-depressed, p=0.03). Vitamins and minerals intake was lower than recommended for both groups; vitamin E intake was associated with depression. In regression models controlling for confounding variables, an increase of 1 mg in vitamin E intake and 1 gram in polyunsaturated fatty acids (PUFA) intake was associated with lower risk for depression (OR=0.73, p=0.008 and OR=0.86, p=0.007 respectively) Participants who reported food insufficiency were 10 times more likely to be depressed compared with those who reported sufficient food. CONCLUSIONS: Given the evaluated adverse association between depressive symptoms and food insufficiency, more efforts are needed to guarantee adequate food intake, particularly foods rich in vitamin E and PUFA, in poor elderly people. Further studies are needed to clarify the temporal relationship between the emotional and nutritional domains in this vulnerable population.

New food composition data on selected ethnic foods consumed in Europe.

BACKGROUND: Reliable data on the composition of foods is needed to better understand individual diets, measure nutrient intakes and provide nutritional guidance for improving the health of the populations. Ethnic foods are becoming increasingly popular among all European consumers, and are the main source of nutrients in the diets of ethnic groups. However, there is limited information on the nutrient composition of ethnic foods in Europe. The objective of this study therefore was to generate new and reliable data on ethnic foods using harmonised methods for chemical analyses. METHODS: New data on 128 ethnic foods were generated for inclusion in the national databases within the European Food Information Resource Network of Excellence through participants from France, Israel, Spain, Denmark, Italy, The Netherlands, Belgium and the United Kingdom. In each selected country, the list of prioritized foods and key nutrients, methods of analyses and quality assurance procedure were harmonised. RESULTS: This paper presents the nutrient composition of 40 ethnic foods consumed in Europe. The nutrient composition of the foods varied widely because of the nature and variety of foods analysed, with energy content (kcal) ranging between 24 (biteku-teku, Blegium) and 495 (nachos, Italy) per 100 g of edible food. Polyunsaturated and monounsaturated fatty acids were generally higher in most ethnic foods consumed in Italy and Spain compared with ethnic foods of other countries. CONCLUSIONS: The new data were scrutinised and fully documented for inclusion in the national food composition databases. The data will aid effective diet and disease interventions, and enhance the provision of dietary advice, in all European consumers.

Importance of ethnic foods as predictors of and contributors to nutrient intake levels in a minority population.

OBJECTIVES: To evaluate the role of ethnic foods as predictors of intake levels of selected nutrients that are important during pregnancy among the Bedouin Arab minority population in southern Israel, and to compare the main food predictors for Bedouin intakes of the selected nutrients with those for the region's Jewish majority population. SUBJECTS/METHODS: Ethnic foods/recipes (n=122) reported in the Bedouin Nutrition Study (BNS) were added to a preexisting, validated Israeli food composition table using European Food Information Resource standard criteria. Food items reported by the 519 BNS participants were combined into 146 food groups that distinguished between existing foods and new ethnic recipes and were entered into a stepwise multiple regression model to identify the main predictors of intake levels of the selected nutrients. The results were compared with those of an identical analysis for the selected nutrients using 24 h recall data from the majority Jewish population. RESULTS: Over 80% of the BNS between-person variability in the intake of all selected nutrients was explained by 34 food groups, of which 13 (38.2%) were ethnic foods. Homemade whole wheat bread was a main predictor of intake levels for five of the eight selected nutrients, and other ethnic foods/recipes (for example, za'atar, leafy dark green vegetables and camel milk) emerged as predictors of iron, folate, calcium and ω-3 fatty acid intakes. Breads explained 60 and 44% of the between-person variation, and 38 and 36% of the total intakes of iron and zinc intakes in the BNS sample, respectively, whereas for the Jewish population, animal sources and fortified foods predominated as main predictors and contributors of these nutrients. CONCLUSIONS: The addition of ethnic foods to food composition databases is important, as some of these foods are main predictors of nutrient intake levels in ethnic minority populations. In turn, this should facilitate the development of more sensitive dietary assessment tools and more effective diet-based health interventions for ethnic minorities.

Electron-phonon decoupling in disordered insulators.

The current-voltage characteristics measured in the insulating state terminating the superconducting phase in disordered superconductors exhibit sharp threshold voltages, where the current abruptly changes by as much as 5 orders of magnitude. We analyze the current-voltage characteristics of an amorphous indium oxide film in the field-tuned insulating state, and show that they are consistent with a bistability of the electron temperature, and with a significant overheating of the electron system above the lattice temperature. An analysis of these current jumps indicates that, in the insulating state, the electrons are thermally decoupled from the phonon bath.

Dietary factors in relation to daily activity energy expenditure and mortality among older adults.

OBJECTIVES: To examine the association between dietary factors to daily activity energy expenditure (DAEE) and mortality among older adults. DESIGN AND SETTING: A sub-study of Health, Aging, and Body Composition study. PARTICIPANTS: 298 older participants (aged 70-82 years) in the Health, Aging, and Body Composition Energy Expenditure sub-study. MEASUREMENTS: Dietary factors, DAEE, and all-cause mortality were measured in 298 older participants. Dietary factors include dietary intake assessed by the Block Food Frequency Questionnaire (FFQ), Healthy Eating Index (HEI), and self-reported appetite and enjoyment of eating. DAEE was assessed using doubly labeled water. All-cause mortality was evaluated over a 9 year period. RESULTS: Participants in the highest tertile of DAEE were more likely to be men and to report having a 'good' appetite; BMI among men, proportion married, IL-6 and CRP levels and energy intake were also higher. Fewer black participants were in the 'good' HEI category. Participants in the 'good' HEI category had higher cognitive scores and a higher education level. Participants who reported improvement in their appetite as well as participants who reported a 'good' appetite were at lower risk for mortality (HR (95% CI): 0.42 (0.24-0.74) and 0.50 (0.26-0.88), respectively) even after adjusting for DAEE, demographic, nutritional and health indices. CONCLUSIONS: We showed an association between DAEE and appetite and mortality among well-functioning, community-dwelling older adults. These findings may have some practical use for the health providers. Inclusion of a question regarding appetite of an elderly patient may provide important information regarding risk for health deterioration and mortality.