136 research outputs found

    Quantum memory: Write, read and reset

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    A model is presented for the quantum memory, the content of which is a pure quantum state. In this model, the fundamental operations of writing on, reading, and resetting the memory are performed through scattering from the memory. The requirement that the quantum memory must remain in a pure state after scattering implies that the scattering is of a special type, and only certain incident waves are admissible. An example, based on the Fermi pseudo-potential in one dimension, is used to demonstrate that the requirements on the scattering process are consistent and can be satisfied. This model is compared with the commonly used model for the quantum memory; the most important difference is that the spatial dimensions and interference play a central role in the present model.Comment: RevTeX4, 7 pages, no figure

    Hemodynamics After Glucose Loading in Hispanics With and Without Family History of Type 2 Diabetes

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    Type 2 Diabetes (T2D) increases cardiovascular mortality 4-fold. Although ~9% of Americans are diagnosed with T2D, T2D incidence is substantially higher in Hispanics and those with a have family history of T2D. Traditionally, T2D is diagnosed via oral glucose testing which has been shown to impair microvascular function. However, the effects of glucose loading on hemodynamics and arterial elasticity between healthy Hispanics with and without a family history of T2D are unclear. PURPOSE: To determine the effects of an oral glucose challenge (OGC) and a mixed meal challenge (MMC) on hemodynamics in healthy Hispanic individuals with and without family history of T2D. METHODS: Thirty-three healthy Hispanic individuals volunteered in this study, including 10 participants with a family history (FH+, 26 ± 7 yrs) of T2D and 23 participants without FH (FH-, 24 ± 5 yrs). Hemodynamics were assessed at rest and 60 minutes after consuming either an OGC or MMC. The OGC consisted of 50g of glucose solution while the MMC consisted of 30g of protein, 5g of fat, and 35g of carbohydrate. A 2x2x2 repeated measures ANOVA was used to evaluate the effects of family history on hemodynamics across conditions and time. RESULTS: FH+ had higher (p. CONCLUSIONS: Healthy Hispanic individuals with family history of type 2 diabetes have higher central and brachial pulse pressure compared to healthy Hispanic individuals without family history of type 2 diabetes. Moreover, glucose loading and mixed meal alter hemodynamics at 60 minutes in healthy Hispanics with and without family history of type 2 diabetes similarly

    Theory and application of Fermi pseudo-potential in one dimension

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    The theory of interaction at one point is developed for the one-dimensional Schrodinger equation. In analog with the three-dimensional case, the resulting interaction is referred to as the Fermi pseudo-potential. The dominant feature of this one-dimensional problem comes from the fact that the real line becomes disconnected when one point is removed. The general interaction at one point is found to be the sum of three terms, the well-known delta-function potential and two Fermi pseudo-potentials, one odd under space reflection and the other even. The odd one gives the proper interpretation for the delta'(x) potential, while the even one is unexpected and more interesting. Among the many applications of these Fermi pseudo-potentials, the simplest one is described. It consists of a superposition of the delta-function potential and the even pseudo-potential applied to two-channel scattering. This simplest application leads to a model of the quantum memory, an essential component of any quantum computer.Comment: RevTeX4, 32 pages, no figure

    Postprandial And Fasting Lipopolysaccharide Levels In Healthy Hispanic Residents Of Southeast Texas With Positive Family History Of Type 2 Diabetes

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    PURPOSE: Healthy people with a family history (FH+) of type 2 diabetes (T2D) display impaired metabolic and microvascular function prior to glucose intolerance, and are at greater risk for developing T2D. While mechanisms to explain this disparity are lacking, it is possible that intestinal permeability plays a role, as it is also linked with insulin resistance, glucose intolerance, and chronic inflammation. Lipopolysaccharides (LPS) act as an outer membrane component of gram-negative bacteria in intestines and play a role in inflammation and chronic disease when in circulation, thus serving as a surrogate measure of intestinal permeability. However, the link between FH+ health disparities and intestinal permeability has not been studied. Thus, the purpose of this study was to quantify circulating plasma LPS in healthy FH+ and FH-. METHODS: In this cross-sectional study, FH- (n=14) and FH+ (n=18) participants matched for age (24.4 ± 1.6 and 25.0 ± 2.3 respectively) and BMI (25.0 ± 1.1 and 25.0 ± 1.1 years respectively) had blood drawn while fasting, and 60-min after consuming a mixed composition meal to quantify changes in plasma LPS, and had body composition determined via iDXA. Other anthropogenic data were collected. RESULTS: Fasting LPS was lower in FH- than FH+ (p \u3c 0.5, 42.3ng/ml ± 5.3 and 48.1ng/ml ± 6.8 respectively) with postprandial LPS increasing more in FH- than FH+ (p\u3c0.05, +10.3ng/ml ± 3.1 and + 1.4ng/ml ± 3.1 respectively). No group differences (p\u3e0.5) were noted in blood pressure (115/69 and 116/69mmHG) LDL-c (4.3mmol/L and 4.4mmol/L), HDL-c (2.2mmol/L and 2.3mmol/L), body fat (29% and 28%), or android fat (30.4% and 30.7%) between FH- and FH+ groups respectively. CONCLUSION: Disparities noted for increase T2D risk in FH+ have been linked to microvascular and metabolic function, with mechanisms for these remaining elusive. However, differences in circulating LPS suggest varying intestinal permeability in these groups, which may help explain the varying risk for T2D. Further work to characterize intestinal microbiota may advance our understanding of health disparities in this and other high-risk populations

    Cardiovascular Responses Differ Between Different Orders of Upper- and Lower-Body Resistance Exercise

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    Upper-body resistance exercise (RE) induces different cardiovascular responses compared to lower-body RE. However, combination of upper- and lower-body RE with different orders on cardiovascular responses are unclear. PURPOSE: To evaluate the effects of different orders of upper-and lower-body RE on cardiovascular responses in active men. METHODS: Thirteen active men (22±2 years old) participated in the study. Heart rate (HR), systolic and diastolic blood pressure (BP), cardiac output (CO), stroke volume (SV), and total peripheral resistance (TPR) were assessed at rest, 15-20 (R1), and 25-30 (R2) minutes after performing upper- and lower-body RE (UL) or lower- and upper-body RE (LU) for 3 sets of 10 repetitions at 75% 1-repetition maximum with 90-second and 2-minute rests between sets and exercises, respectively. The upper-body RE consisted of pulldown and chest press while lower-body RE consisted of knee extension and knee flexion. A repeated measures ANOVA was used to evaluate the conditions (UL, LU) across time (rest, R1, R2) on cardiovascular responses. RESULTS: There were time-by-condition interactions (p\u3c0.05) for CO and SV such that CO was significantly elevated at R1 and R2 after UL and LU compared to rest while UL had higher CO compared to LU at R1 (UL: rest: 5.68±0.99 L/min; R1: 9.09±1.44 L/min; R2: 7.65±1.87 L/min; and LU: rest: 5.55±0.78 L/min; R1: 8.14±1.65 L/min; R2: 7.23±1.76 L/min). SV was significantly increased after UL at R1 compared to rest and LU (UL: rest: 85.2±16.5 ml/beat; R1: 90.9±14.3 ml/beat; R2: 81.8±18.8 ml/beat; and LU: rest: 84.7±12.7 ml/beat; R1: 83.0±13.9 ml/beat; R2: 78.6±16.2 ml/beat). TPR was significantly (p\u3c0.001) reduced at R1 and R2 compared to rest after UL and LU with greater reduction after UL compared to LU (UL: rest: 0.96±0.27 mmHg•min/L; R1: 0.53±0.16 mmHg•min/L; R2: 0.68±0.22 mmHg•min/L; and LU: rest: 1.03±0.33 mmHg•min/L; R1: 00.67±0.26 mmHg•min/L; R2: 0.77±0.26 mmHg•min/L). HR was significantly (p\u3c0.001) increased at R1 and R2 after UL and LU compared to rest. Systolic BP was significantly (p=0.026) decreased after LU at R1 compared to rest and R2. However, there was no change for diastolic BP. CONCLUSION: These data suggest that UL significantly increases cardiac output and stroke volume than LU which means different orders of RE change cardiovascular responses

    Autonomic modulation in older women: using resistance exercise as a countermeasure

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    International Journal of Exercise Science 10(2): 178-187, 2017 It is unclear if resistance training (RT) can be used to alter declines in autonomic modulation associated with aging. Young women (YW; range 18-25 yrs) and older women (OW; range 50-72 yrs) were compared at baseline. Only OW underwent supervised RT 2 days a week for 12-weeks. Baseline and post-training measurements included heart rate variability (HRV) and complexity (Sample Entropy) to assess autonomic modulation. The 12-weeks of RT consisted of 9 exercises performing 3 sets of 8-12 repetitions. At baseline, group differences in maximal strength, and autonomic modulation were evaluated with a one-way ANOVA with BMI as a covariate. In the OW, the effects of RT were evaluated with repeated-measures ANOVA in order to compare baseline to after RT. The YW had significantly (p≤0.05) lower diastolic, but not systolic blood pressure. The YW also had significantly (p≤0.05) greater absolute Ln (natural logarithm) high-frequency (HF) power and normalized HF power compared to the OW. In addition, there were significantly (p≤0.05) greater levels of normalized low-frequency power (LF) (and the LF/HF ratio) in the OW compared to the YW before RT. However, no difference was found for Sample Entropy. After RT, OW significantly (p≤0.05) increased the chest press (28%) and leg extension (33%). RT had no significant effect on any autonomic parameter suggesting that it may not be a sufficient stimulus to alter the effects of aging

    The Effects of Machine-Weight and Free-Weight Resistance Exercise on Hemodynamics and Vascular Function

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    International Journal of Exercise Science 13(2): 526-538, 2020. The purpose of this study was to examine hemodynamic and vascular responses between machine-weight and free-weight exercise. Resistance-trained individuals were assigned to a machine-weight (n= 13) or free-weight (n= 15) group. Groups completed two visits consisting of their assigned exercise condition and a control (CON). A 2 x 2 x 3 repeated measures ANOVA was used to test the effects of group across condition and time on the hemodynamic parameters [cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), mean arterial pressure (MAP), and stroke volume (SV)]. A 2 x 2 x 2 repeated measures ANOVA was used to test the effects of group across condition and time on the hemodynamic variable, forearm vascular conductance (FVC), as well as on vascular measures [forearm blood flow (FBF), blood flow peak, and total reactive hyperemia (RH)]. Main effects were analyzed using pairwise comparisons. The results of the present study demonstrate that both machine-weight and free-weight exerciseproduce similar (p \u3e 0.05)alterations in hemodynamics and vascular function. Specifically, during recovery both groups demonstrated significant (p ≤ 0.05) increases in measures of hemodynamics such as CO, HR and FVC, as well as significant (p ≤ 0.05) decreases in TPR, MAP, and SV. Measures of vascular function such as FBF, blood flow peak, and total RH were also significantly (p ≤ 0.05) increased during recovery.Therefore, this study suggests that either machine weight or free-weight exercise may induce acute hemodynamic and vascular benefits, which may reduce the risk of cardiovascular disease (CVD) and CVD events

    Vascular Insulin Resistance May Contribute to Health Disparities in People from the Rio Grande Valley

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    Microvascular blood flow (MBF) increases postprandially in skeletal muscle in response to insulin to aid in myocyte glucose delivery. This MBF response is considered a measure of vascular insulin resistance and can be impaired with altered meal composition, obesity, type 2 diabetes mellitus (T2DM), and insulin resistance. Current studies indicate this MBF response to a mixed meal challenge (MMC) may identify vascular insulin resistance before typically-presenting serum biomarkers of insulin resistance, as it displays more sensitivity than when using an oral glucose challenge (OGC). However, it is unknown if healthy adults residing in the Rio Grande Valley (RGV), an area with a 3x higher prevalence of T2DM vs the national average, demonstrate impaired MBF responses similar to those seen in overt insulin resistance. PURPOSE: To determine microvascular responses in apparently healthy individuals of the RGV between OGC and MMC. METHODS: 17 healthy participants from the RGV (age 25±6 yrs, BMI 25±3 kg/m2, fat mass % 29±9%, and android fat % 31±10.4%) without hypertension, T2DM, or dyslipidemia were administered a MMC and OGC on two separate occasions. Forearm skeletal muscle MBF (measured as acoustic intensity/second (AI/s)) was recorded pre- and 1-hour postprandial via contrast-enhanced ultrasound (CEU). RESULTS: MMC pre- vs. post-prandial demonstrated a 0.59 fold reduction (1.6101 vs. 0.6548 AI/s, 95% CI [-.2871, 3.5073] and [0.887, 1.2209], respectively). OGC pre- vs. post-prandial MBF had a 0.18 fold reduction (1.6734 vs. 1.3693 AI/s, 95% CI [.3755, 2.9714] and [.4725, 2.2661], respectively). MBF in skeletal muscle demonstrated no significant difference between MMC and OGC groups (Mean square= 2.378, F(1, 48) = .320, p = 0.574). CONCLUSION: Unlike healthy Caucasians, apparently healthy residents of the RGV display impaired microvascular responses to MMC, similar to using an OGC, suggesting early vascular insulin resistance. As this population displays significant health disparities for chronic diseases such as T2DM, obesity, and Alzheimer’s, it is plausible that early vascular insulin resistance noted in this population significantly contributes to the increased incidence of these chronic diseases. Additional research is needed to identify mechanisms explaining this population\u27s etiology of impaired MBF responses and vascular insulin resistance

    Hemodynamic response and pulse wave analysis after upper- and lower-body resistance exercise with and without blood flow restriction

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    Resistance exercise (RE) has been shown to elevate hemodynamics and pulse wave reflection. However, the effects of acute RE with blood flow restriction (BFR) on hemodynamics and pulse wave reflection are unclear. The purpose of this study was to evaluate the differences between upper- and lower-body RE with and without BFR on hemodynamics and pulse wave reflection. Twenty-three young resistance-trained individuals volunteered for the study. Hemodynamics and pulse wave reflection were assessed at rest, 10, 25, 40, and 55 minutes after either upper- or lower-body with or without BFR. The upper-body RE (URE) consisted of the latissimus dorsi pulldown and chest press; the lower-body RE (LRE) consisted of knee extension and knee flexion. The BFR condition consisted of four sets of 30, 15, 15, and 15 repetitions at 30% 1-repetition maximum (1RM) while the without BFR condition consisted of four sets of 8 repetitions at 70% 1RM. Heart rate, rate pressure product, and subendocardial viability ratio significantly (p\u3c0.05) increased after all exercises. Brachial and aortic systolic blood pressure (BP) significantly (p\u3c0.05) elevated after LRE while brachial and aortic diastolic BP significantly (p\u3c0.05) reduced after URE. Augmentation pressure, augmentation index (AIx), AIx normalized at 75 bpm, and wasted left ventricular pressure energy significantly (p\u3c0.05) increased after URE while transit time of reflected wave significantly (p\u3c0.05) decreased after LRE. URE places greater stress on pulse wave reflection while LRE results in greater responses in BP. Regardless of URE or LRE, the cardiovascular responses between BFR and without BFR are similar

    The Effects of Machine-Weight and Free-Weight Resistance Exercise on Hemodynamics and Vascular Function

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    The purpose of this study was to examine hemodynamic and vascular responses between machine-weight and free-weight exercise. Resistance-trained individuals were assigned to a machine-weight (n = 13) or free-weight (n = 15) group. Groups completed two visits consisting of their assigned exercise condition and a control (CON). A 2 × 2 × 3 repeated measures ANOVA was used to test the effects of group across condition and time on the hemodynamic parameters [cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), mean arterial pressure (MAP), and stroke volume (SV)]. A 2 × 2 × 2 repeated measures ANOVA was used to test the effects of group across condition and time on the hemodynamic variable, forearm vascular conductance (FVC), as well as on vascular measures [forearm blood flow (FBF), blood flow peak, and total reactive hyperemia (RH)]. Main effects were analyzed using pairwise comparisons. The results of the present study demonstrate that both machine-weight and free-weight exercise produce similar (p \u3e 0.05) alterations in hemodynamics and vascular function. Specifically, during recovery both groups demonstrated significant (p ≤ 0.05) increases in measures of hemodynamics such as CO, HR and FVC, as well as significant (p ≤ 0.05) decreases in TPR, MAP, and SV. Measures of vascular function such as FBF, blood flow peak, and total RH were also significantly (p ≤ 0.05) increased during recovery. Therefore, this study suggests that either machine weight or free-weight exercise may induce acute hemodynamic and vascular benefits, which may reduce the risk of cardiovascular disease (CVD) and CVD events
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