Topics concerning state variable feedback in automatic control systems. Part 1 - Specification. Part 2 - Sensitivity. Part 3 - Intentional nonlinearities. Part 4 - Unavailable states

Specifications, sensitivity, intentional nonlinearities, and unavailable states concerned with state variable feedback in automatic control system

Effects of Time-Restricted Exercise on Training Induced Adaptations in Mice

Recent studies have shown that the time of day that exercise is performed can alter the physiological and molecular response. However, very few studies have investigated the longitudinal effects of time-of-day dependent training. Identification of an optimal exercise timing could lead to subsequent exercise prescriptions to elicit specific adaptations based on desired outcomes in healthy or disease populations. PURPOSE: The purpose of this study was to determine if voluntary exercise performed at different times of day would alter the physiological response to training. METHODS: Male C57BL/6 mice (Jackson Labs) housed on a strict 12:12 light dark cycle performed 4 weeks of voluntary exercise training on a wireless running wheel, in a time-of-day dependent manner. Mice were allocated to three groups (n = 10/group): 1) Sedentary (locked wheel), 2) Early Active Phase exercise (EAP; wheel unlocked during the first half of the dark/active phase), or 3) Late Active Phase exercise (LAP; wheel unlocked during the second half of the dark/active phase). Endurance capacity was tested via graded exercise tests (GXTs) at baseline, 2- and 4-weeks. Body weight was recorded at the same times. RESULTS: We found the EAP mice accrued significantly more voluntary exercise compared to LAP mice (7.34 ± 0.55 km/session vs 4.70 ± 0.38 km/session, p \u3c 0.001). Interestingly, EAP and LAP mice both improved on the GXT to a similar extent, and both performed significantly better than SED mice (537.2 ± 68.3 m, vs 467.6 ± 27.7 m, vs 262.7 ± 15.3 m, respectively; p \u3c 0.05). Throughout the training period, SED and EAP mice gained similar amounts of weight, while LAP mice gained less weight (1.4 ± 0.2 g, vs 0.4 ± 0.4 g, vs 1.3 ± 0.3 g, respectively). CONCLUSION: Based on these findings, mice preferentially perform nearly 50% more exercise during the early active phase compared to the late active phase. However, no significant difference exists in the GXT performance between EAP and LAP mice. These findings suggest that LAP exercise may confer similar adaptations with substantially lower volume

Effects of Social Jetlag on Exercise-Induced Adaptations in Skeletal Muscle Mitochondrial Content in Mice

Social jetlag (SJL) occurs when the sleep/wake schedule differs on work days (weekdays) and free days (weekends). Previous studies have shown that individuals with SJL have lower physical fitness and are prone to obesity. While exercise reverses this phenotype (i.e. - via increasing skeletal muscle mitochondrial content), the effects of social jetlag on exercise training adaptations have yet to be shown. PURPOSE: To determine how social jetlag impacts skeletal muscle adaptations to exercise training in mice. METHODS: Male C57BL/6J mice aged 10-weeks (n=40) were assigned to four groups, with experimental conditions persisting for 6-weeks; control sedentary (C-SED), control with voluntary wheel exercise (C-EX), social jetlag sedentary (SJL-SED), and social jetlag with exercise (SJL-EX). SJL was introduced weekly via 4h shifts in light/dark cycles on weekends. Skeletal muscles (quad, gas, sol) were collected for gravimetric analysis, and assessment of circadian clock gene expression and mitochondrial content. RESULTS: Mice with SJL had larger quadriceps (ME-SJL, p\u3c0.05), but this effect was lost when normalized to BW. Exercised mice had smaller quadriceps (ME-EX, p\u3c0.05), and larger solei (ME-EX, p\u3c0.05). No effects of SJL were seen in solei. SJL led to alterations in PER1, PER2, and CRY2 expression (ME-SJL, p\u3c0.05 all), while exercise led to reductions in PER2 and CRY2 expression (ME-EX, p\u3c0.05), with no interactions reaching significance. Exercise increased OXPHOS complex expression (ME Exercise; C-V, C-III, C-I, all p\u3c0.05), which was attenuated by SJL (ME SJL; C-II, C-I, p\u3c0.05). We found an interaction in C-IV expression where the exercise-induced increase was blunted in SJL-EX mice (p\u3c0.05). CONCLUSION: These data suggest that, while exercise has a beneficial impact on mitochondrial content in skeletal muscle, social jetlag prevents some of the exercise-induced improvements, potentially via disruption of the muscle circadian clock

Social Jetlag Inhibits Exercise-Induced Adaptations in the Heart and Alters Markers of Mitochondrial Dynamics

Social jetlag (SJL), or the shifting of behavior and sleep times between weekdays and weekends, is a pervasive form of circadian rhythm disruption that affects nearly 70% of the population to some extent. The magnitude of SJL can be determined by the difference in the mid-sleep phase between weekends and weekdays. Higher levels of SJL have been associated with lower levels of cardiorespiratory fitness, and increased incidence of cardiometabolic disease, which may be due, in part, to mitochondrial dysfunction. However, no studies to date have evaluated the effects of long term SJL on cardiac mitochondrial dynamics. PURPOSE: To determine the effect of SJL on mitochondrial fission and fusion signaling in the heart, and if exercise protects the heart against SJL. METHODS: Male C57BL/6 mice (n = 40) were allocated to four groups (n = 10/group): 1) Control Light:Dark cycle, Sedentary (CON-SED), 2) Control Light:Dark cycle, Exercise (CON-EX), 3) SJL, sedentary (SJL-SED), or SJL, exercise (SJL-EX). SJL was implemented by delaying the LD cycle 4 hours on ‘Fridays,’ and advancing the LD cycle on Mondays. Exercise was provided ad libitum with a disc. Conditions persisted for 6 weeks at which point hearts were harvested for gravimetric analysis and western blotting of markers of mitochondrial dynamics. RESULTS: Exercise caused myocardial hypertrophy in both control and SJL LD conditions (Main Effect – EX, p \u3c 0.05), with no difference between CON and SJL conditions. We did not observe any significant differences in mitochondrial content (OXPHOS antibody cocktail, p \u3e 0.05), SJL decreased expression of mitochondrial fusion proteins MFN1 and OPA1 (Main Effect – SJL, p \u3c 0.05). Importantly, SJL inhibited exercise-induced increases in MFN2 (p \u3c 0.05), suggesting that SJL specifically ameliorates some exercise-induced adaptations in mitochondrial dynamics in the heart. CONCLUSION: These findings suggest that exercise induces adaptations in mitochondrial dynamics, potentially increasing mitochondrial function, and SJL may disrupt mitochondrial dynamics both in the sedentary and exercise trained states

The association between histamine 2 receptor antagonist use and Clostridium difficile infection: a systematic review and meta-analysis.

Background Clostridium difficile infection (CDI) is a major health problem. Epidemiological evidence suggests that there is an association between acid suppression therapy and development of CDI. Purpose We sought to systematically review the literature that examined the association between histamine 2 receptor antagonists (H2RAs) and CDI. Data source We searched Medline, Current Contents, Embase, ISI Web of Science and Elsevier Scopus from 1990 to 2012 for all analytical studies that examined the association between H2RAs and CDI. Study selection Two authors independently reviewed the studies for eligibility. Data extraction Data about studies characteristics, adjusted effect estimates and quality were extracted. Data synthesis Thirty-five observations from 33 eligible studies that included 201834 participants were analyzed. Studies were performed in 6 countries and nine of them were multicenter. Most studies did not specify the type or duration of H2RAs therapy. The pooled effect estimate was 1.44, 95% CI (1.22–1.7), I2 = 70.5%. This association was consistent across different subgroups (by study design and country) and there was no evidence of publication bias. The pooled effect estimate for high quality studies was 1.39 (1.15–1.68), I2 = 72.3%. Meta-regression analysis of 10 study-level variables did not identify sources of heterogeneity. In a speculative analysis, the number needed to harm (NNH) with H2RAs at 14 days after hospital admission in patients receiving antibiotics or not was 58, 95% CI (37, 115) and 425, 95% CI (267, 848), respectively. For the general population, the NNH at 1 year was 4549, 95% CI (2860, 9097). Conclusion In this rigorous systematic review and meta-analysis, we observed an association between H2RAs and CDI. The absolute risk of CDI associated with H2RAs is highest in hospitalized patients receiving antibiotics

Effect of Oscillating Landau Bandwidth on the Integer Quantum Hall Effect in a Unidirectional Lateral Superlattice

We have measured activation gaps for odd-integer quantum Hall states in a unidirectional lateral superlattice (ULSL) -- a two-dimensional electron gas (2DEG) subjected to a unidirectional periodic modulation of the electrostatic potential. By comparing the activation gaps with those simultaneously measured in the adjacent section of the same 2DEG sample without modulation, we find that the gaps are reduced in the ULSL by an amount corresponding to the width acquired by the Landau levels through the introduction of the modulation. The decrement of the activation gap varies with the magnetic field following the variation of the Landau bandwidth due to the commensurability effect. Notably, the decrement vanishes at the flat band conditions.Comment: 7 pages, 6 figures, minor revisio

Surface Production Fuels Deep Heterotrophic Respiration in Northern Peatlands

Multiple analyses of dissolved organic carbon (DOC) from pore waters were conducted to define the processes that govern carbon balance in peatlands: (1) source, reactivity, and transport of DOC with respect to vegetation, peat, and age of carbon substrate, (2) reactivity of DOC with respect to molecular size, and (3) lability to photoxidation of surficial DOC. We found that surface organic production fuels heterotrophic respiration at depth in advection-dominated peatlands, especially in fens. Fen DOC was Δ14Cenriched relative to the surrounding fen peat, and fen respiration products were similar to this enriched DOC indicating that DOC was the main microbial substrate. Bog DOC was more variable showing either enrichment in Δ14C at depth or Δ14C values that follow peat values. This variability in bogs is probably controlled by the relative importance of vertical transport of labile carbon substrates within the peat profile versus DOC production from bog peat. These results extended our set of observations to 10 years at one bog-fen pair and add two additional bog-fen pairs to our series of observations. Anaerobic incubations of peat, rinsed free of residual DOC, produced DOC and respiration products that were strikingly similar to the peat values in a bog and two fens. This result demonstrated conclusively that downward advection is the process responsible for the presence of modern DOC found at depth in the peat column. Fen DOC has lower C/N values and up to twice as much LMW (kDa) DOC as bogs due to differences in organic inputs and greater microbial processing. Fluorescence irradiation experiments showed that fen DOC is more photolabile than bog DOC

HI, FRB, what's your z: The first FRB host galaxy redshift from radio observations

Identification and follow up observations of the host galaxies of fast radio bursts (FRBs) not only help us understand the environments in which the FRB progenitors reside, but also provide a unique way of probing the cosmological parameters using the dispersion measures of FRBs and distances to their origin. A fundamental requirement is an accurate distance measurement to the FRB host galaxy, but for some sources viewed through the Galactic plane, optical/NIR spectroscopic redshifts are extremely difficult to obtain due to dust extinction. Here we report the first radio-based spectroscopic redshift measurement for an FRB host galaxy, through detection of its neutral hydrogen (HI) 21-cm emission using MeerKAT observations. We obtain an HI-based redshift of z = 0.0357 for the host galaxy of FRB 20230718A, an apparently non-repeating FRB detected in the CRAFT survey and localized at a Galactic latitude of -0.367 deg. Our observations also reveal that the FRB host galaxy is interacting with a nearby companion, which is evident from the detection of an HI bridge connecting the two galaxies. A subsequent optical spectroscopic observation confirmed an FRB host galaxy redshift of 0.0359 +- 0.0004. This result demonstrates the value of HI to obtain redshifts of FRBs at low Galactic latitudes and redshifts. Such nearby FRBs whose dispersion measures are dominated by the Milky Way can be used to characterise these components and thus better calibrate the remaining cosmological contribution to dispersion for more distant FRBs that provide a strong lever arm to examine the Macquart relation between cosmological DM and redshift.Comment: 13 pages, 3 figures. Accepted to ApJ Letter

The effect of oscillating Fermi energy on the line shape of the Shubnikov-de Haas oscillation in a two dimensional electron gas

The line shape of the Shubnikov-de Haas (SdH) oscillation has been analyzed in detail for a GaAs/AlGaAs two-dimensional electron gas. The line shape, or equivalently the behavior of the Fourier components, of the experimentally observed SdH oscillation is well reproduced by the sinusoidal density of states at the Fermi energy that oscillates with a magnetic field in a saw-tooth shape to keep the electron density constant. This suggests that the broadening of each Landau level by disorder is better described by a Gaussian than by a Lorentzian.Comment: 7 pages,6 figures, minor revision

Scaling properties of protein family phylogenies

One of the classical questions in evolutionary biology is how evolutionary processes are coupled at the gene and species level. With this motivation, we compare the topological properties (mainly the depth scaling, as a characterization of balance) of a large set of protein phylogenies with a set of species phylogenies. The comparative analysis shows that both sets of phylogenies share remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees. Thus, the rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level.Comment: Replaced with final published versio