Prolonged Periods Of Inactivity Research Articles

I'll Be Back: On the Multiple Lives of Users of a Mobile Activity Tracking Application.

Mobile health applications that track activities, such as exercise, sleep, and diet, are becoming widely used. While these activity tracking applications have the potential to improve our health, user engagement and retention are critical factors for their success. However, long-term user engagement patterns in real-world activity tracking applications are not yet well understood. Here we study user engagement patterns within a mobile physical activity tracking application consisting of 115 million logged activities taken by over a million users over 31 months. Specifically, we show that over 75% of users return and re-engage with the application after prolonged periods of inactivity, no matter the duration of the inactivity. We find a surprising result that the re-engagement usage patterns resemble those of the start of the initial engagement period, rather than being a simple continuation of the end of the initial engagement period. This evidence points to a conceptual model of multiple lives of user engagement, extending the prevalent single life view of user activity. We demonstrate that these multiple lives occur because the users have a variety of different primary intents or goals for using the app. These primary intents are associated with how long each life lasts and how likely the user is to re-engage for a new life. We find evidence for users being more likely to stop using the app once they achieved their primary intent or goal (e.g., weight loss). However, these users might return once their original intent resurfaces (e.g., wanting to lose newly gained weight). We discuss implications of the multiple life paradigm and propose a novel prediction task of predicting the number of lives of a user. Based on insights developed in this work, including a marker of improved primary intent performance, our prediction models achieve 71% ROC AUC. Overall, our research has implications for modeling user re-engagement in health activity tracking applications and has consequences for how notifications, recommendations as well as gamification can be used to increase engagement.

All roads leading to Rome? The medium term outcomes of Australian youth’s transition pathways from education

ABSTRACTYoung people’s transition from education into the labour market are diverse: sometimes direct from school to work or inactivity, sometimes characterised by stop-starts and combinations of different activities. This paper explores the association between transition pathways of Australian youth and their outcomes, in terms of earnings, perceptions of employment opportunities and debt. It builds on analysis by Fry and Boulton [2013. Prevalence of Transition Pathways in Australia. Canberra: Productivity Commission Staff Working Paper] who identified five pathways most typically taken by 15–24 year old Australians over a 10 year period, including quasi linear transitions from education to work with and without study, combinations of work and study, multiple churning between labour market statuses, and transitions into prolonged periods of inactivity. The present study adds four more years of panel data that have since become available, and compares the labour market outcomes of the different pathways at age 29–38. Earnings and employment perception converged over time, but debt did not. Socio-demographics were most strongly associated with outcomes, but earnings were also greater for churners and for young people in extended education increasingly combined with work. Transitions that combined learning and work seemingly strategically or ‘flexibly’ appeared most rewarding in the medium term, although neither compensated for socio-economic difference.

“Stiction Syndrome”: Non-Operative Management of Patients With Difficult AMS 700 Series Inflation

IntroductionStatic friction (stiction) is a mechanical phenomenon in which a state of increased resistance exists across a control valve mechanism. AimTo present a strategy for non-operative management of inflatable penile prosthesis (IPP) cases with pump malfunction from pump valve stiction. MethodsAll patients had American Medical Systems (AMS; Minnetonka, MN, USA) 700 series Momentary Squeeze IPPs with transient pump malfunction owing to pump valve stiction after extended periods of device inactivity. Main Outcome MeasuresOur evolving non-operative management experience with the “forced deflation” maneuver is described. This technique has successfully prevented the need for surgical pump replacement. Of patients with IPP who were instructed to inflate and deflate daily to prevent stiction recurrence, none have re-presented with difficult inflation. ResultsOf 306 patients receiving the AMS 700 series IPP at our institution from 2007 through 2015, 6 (1.9%) presented with difficulty activating the Momentary Squeeze pump (from 2011 through 2015). Four additional patients were referred from outside institutions with the same complaint. All patients (10 of 10, 100%) presented after a prolonged period of inactivity (minimum = 6 weeks) during which the IPP was not cycled and remained stagnant. Although the initial four patients (40%) underwent surgical exploration with pump mobilization and replacement, the six most recent patients (60%) were successfully instructed in the forced deflation maneuver in the office, which enabled the device to cycle normally thereafter. ConclusionDevice inactivity, for as little as 6 weeks, can predispose to Momentary Squeeze pump valve malfunction; and a regimen of daily IPP cycling could prevent stiction-related malfunction. Our findings should encourage practitioners to attempt conservative management of patients with “stiction syndrome” whenever possible, thereby avoiding unnecessary surgery.Kavoussi NL, Viers BR, VanDyke ME, et al. “Stiction Syndrome”: Non-Operative Management of Patients With Difficult AMS 700 Series Inflation. J Sex Med 2017;14:1079–1083.

Inédit 1 (1964): Réflexions sur les possibilités d’une description de l’histoire de la linguistique

AbstractThe Wenner-Gren Foundation symposium “Revolution vs. Continuity in the Study of Language” invites speakers to discuss the applicability of Thomas Kuhn’s 1962 essay to linguistics. Kuhn does well to posit an autonomous epistemological plane, to take account of the sociology of knowledge, and to focus on the history of structures rather than of fleeting events. On the other hand, he presents each science as essentially stagnant throughout most of time, and offers an atemporal and harmonious view of how one “paradigm” replaces its predecessor; Kuhnian history emerges as a succession of synchronies. The portrayal ignores that if paradigms emerge at successive moments, old and new overlap and coexist in tension. Constructing each science as an independent system, it also neglects dynamics that cross or connect disciplines, including generalized systems of thought, and outlooks common to an entire society at a given era.Whereas sciences today are familiar with synchronic systems, effective models of those structures’ diachronic transformation are lacking. Rather than Kuhn’s or Hegel’s a priori and overly general schemas, inductive approaches based on the linguistic analysis of scholarship or researchers’ autobiographical testimonies could provide better results. In the interim, adopting Braudel’s concept of history as encompassing events belonging to three distinct chronological orders ranging from quotidian to multi-secular, we can see that a Kuhnian revolution alters views characteristic of a discipline during a given period, but only changes portions of the overall field as it has developed throughout time. This conception reconciles synchrony and diachrony. Rather than prolonged periods of inactivity, we observe a constant scientific praxis which transforms paradigms defined as open, their possibilities always exceeding their extant realizations. Such paradigmatic variations cannot account for exceptional scientific revolutions which exceed their scale, such as the invention of writing, and which represent instead breakthroughs in a model’s effectiveness, in its ability to transform reality and human experience. The contemporary project for a structural semantics aims to achieve a second linguistic revolution by constructing a new language which can serve as the science of humanity, an anthropology comparable to the mathematics used in the life sciences.

Wireless power transfer system for a human motion energy harvester

Human motion energy harvesting as an alternative to battery powering in body worn and implanted devices is challenging during prolonged periods of inactivity. Even a buffer energy storage system will run out of power eventually if there is no external acceleration to the harvester. This paper presents a method to actuate the rotor inside a previously presented rotational piezoelectric energy harvester wirelessly via a magnetic reluctance coupling to an external driving rotor with one or more permanent magnet stacks attached. This makes it possible to recharge a battery or super-capacitor even if a patient is not moving. The use of a permanent magnet coupling has potential advantages compared to traditional inductive or ultrasonic methods, e.g. in terms of tissue damage and transmission depth. Simulation results show the achievable coupling torque for different configurations of magnet geometries and relative positions between the driving magnet stack(s) and the harvester. It is shown that using a single magnet stack yields better results than using two diametrically opposite stacks. Measurements are performed with different magnets, driving frequencies and orientations of the harvester. The results are discussed and successful energy transfer was achieved regardless of the orientation of the device with respect to gravity, which is desirable for real world applications. Lateral misalignment between the harvester and the driving magnet can also be overcome. The largest distance of power transfer reached was 32mm with the largest magnets tested, and the optimal power output into a resistive load was over 100μW at a frequency of 25Hz. The functional volume of the harvester is 1.85cm3 – similar to the size of a wristwatch.

Skeletal muscle mass and composition during mammalian hibernation.

Hibernation is characterized by prolonged periods of inactivity with concomitantly low nutrient intake, conditions that would typically result in muscle atrophy combined with a loss of oxidative fibers. Yet, hibernators consistently emerge from winter with very little atrophy, frequently accompanied by a slight shift in fiber ratios to more oxidative fiber types. Preservation of muscle morphology is combined with down-regulation of glycolytic pathways and increased reliance on lipid metabolism instead. Furthermore, while rates of protein synthesis are reduced during hibernation, balance is maintained by correspondingly low rates of protein degradation. Proposed mechanisms include a number of signaling pathways and transcription factors that lead to increased oxidative fiber expression, enhanced protein synthesis and reduced protein degradation, ultimately resulting in minimal loss of skeletal muscle protein and oxidative capacity. The functional significance of these outcomes is maintenance of skeletal muscle strength and fatigue resistance, which enables hibernating animals to resume active behaviors such as predator avoidance, foraging and mating immediately following terminal arousal in the spring.

Using Multiple Imputations to Accommodate Time-Outs in Online Interventions

BackgroundAccurately estimating the period of time that individuals are exposed to online intervention content is important for understanding program engagement. This can be calculated from time-stamped data reflecting navigation to and from individual webpages. Prolonged periods of inactivity are commonly handled with a time-out feature and assigned a prespecified exposure duration. Unfortunately, this practice can lead to biased results describing program exposure.ObjectiveThe aim of the study was to describe how multiple imputations can be used to better account for the time spent viewing webpages that result in a prolonged period of inactivity or a time-out.MethodsTo illustrate this method, we present data on time-outs collected from the Q2 randomized smoking cessation trial. For this analysis, we evaluate the effects on intervention exposure of receiving content written in a prescriptive versus motivational tone. Using multiple imputations, we created five complete datasets in which the time spent viewing webpages that resulted in a time-out were replaced with values estimated with imputation models. We calculated standard errors using Rubin’s formulas to account for the variability due to the imputations. We also illustrate how current methods of accounting for time-outs (excluding timed-out page views or assigning an arbitrary viewing time) can influence conclusions about participant engagement.ResultsA total of 63.00% (1175/1865) of participants accessed the online intervention in the Q2 trial. Of the 6592 unique page views, 683 (10.36%, 683/6592) resulted in a time-out. The median time spent viewing webpages that did not result in a time-out was 1.07 minutes. Assuming participants did not spend any time viewing a webpage that resulted in a time-out, no difference between the two message tones was observed (ratio of mean time online: 0.87, 95% CI 0.75-1.02). Assigning 30 minutes of viewing time to all page views that resulted in a time-out concludes that participants who received content in a motivational tone spent less time viewing content (ratio of mean time online: 0.86, 95% CI 0.77-0.98) than those participants who received content in a prescriptive tone. Using multiple imputations to account for time-outs concludes that there is no difference in participant engagement between the two message tones (ratio of mean time online: 0.87; 95% CI 0.75-1.01).ConclusionsThe analytic technique chosen can significantly affect conclusions about online intervention engagement. We propose a standardized methodology in which time spent viewing webpages that result in a time-out is treated as missing information and corrected with multiple imputations.Trial RegistrationClinicaltrials.gov NCT00992264; http://clinicaltrials.gov/ct2/show/NCT00992264 (Archived by WebCite at http://www.webcitation.org/6Kw5m8EkP).

CrossTalk proposal: Mechanical ventilation‐induced diaphragm atrophy is primarily due to inactivity

CrossTalk proposal: Mechanical ventilation‐induced diaphragm atrophy is primarily due to inactivity

Hip pain while using lower extremity joints and sleep disturbances in elderly white women: Results from a cross‐sectional analysis

To evaluate sleep quality in women with hip pain due to daily activities involving the lower extremity joints. We evaluated the association of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) hip pain severity score with objective sleep measures obtained by wrist actigraphy in 2,225 white women ≥ 65 years of age enrolled in the Study of Osteoporotic Fractures. Women had an increased odds of spending ≥ 90 minutes awake after sleep onset (odds ratio [OR] 1.28, 95% confidence interval [95% CI] 1.11-1.50) for every 5-point increase in hip pain score after adjustment for all covariates. Hip pain when sitting or lying was the strongest predictor of sleep fragmentation (OR 2.0, 95% CI 1.47-2.73); however, standing pain was associated with a higher number of awake minutes in bed scored from sleep onset to the end of the last sleep episode, independent of pain while in bed (OR 1.41, 95% CI 1.07-2.01). Sleep disturbances increased significantly after the first 2 hours of sleep in women with severe hip pain compared to those without hip pain (mean ± SD 1.4 ± 0.47 minutes per hour of sleep; P < 0.003). Similar associations were observed for long wake episodes >5 minutes. There were no associations between daytime napping, sleep latency, sleep efficiency, and total sleep minutes and WOMAC hip pain. Fragmented sleep was greater in women with hip pain compared to those without hip pain; however, fragmented sleep in women with severe hip pain compared to those without hip pain was unchanged until after the first 2 hours of sleep. Further investigations into pain medications wearing off over time or the prolonged periods of inactivity decreasing the pain threshold are warranted.

Neuroprotectin D1 Attenuates Epileptogenesis (IN5-1.001)

Objective: We determined the role of NPD1 in the development of recurrent seizures in a post status epilepticus model of epileptogenesis. Background Epileptogenesis involves neuroinflammatory signaling that contributes to synaptic activity dysfunction that leads to neuronal network rearrangement and fosters recurrent seizures. Neuroprotectin D1 (NPD1) a derivative of the omega 3 fatty acid, docosahexaenoic acid, limits seizures susceptibility and induces neuroprotection after brain injury. Design/Methods: Multi-microelectrodes were implanted in the dorsal hippocampus in adult male mice after status epilepticus (SE) induced by pilocarpine. NPD1 or Vehicle was administered systemically during the 5 days after SE. Local field potentials and spike units from hippocampal regions were recorded using data acquisition systems at different time points. Time-dependent changes of the oscillatory activity of hippocampal networks were analyzed, including interictal spikes (IS), microseizures, high frequency oscillations, and spike unit activity. Recurrent seizure activity was video-recorded during the 3 weeks after SE. Brains were dissected and dendrites of principal cells from hippocampal regions were analyzed using Golgi staining. Results: Microseizures were observed during epileptogenesis in different hippocampal layers at frequencies of 4-8 microseizures/min. Frequencies above 150 Hz (high-frequency oscillations; HFOs) were observed in all hippocampal fields but were increased only in the dentate gyrus. The interictal period showed burst-like neuronal activity with a prolonged period of inactivity (a sustained firing pattern in control animals) and were correlated with a loss of dendritic spines. NPD1-treated mice had less recurrent seizure frequency and duration. During epileptogenesis, NPD1 attenuates pathological HFO and microseizures, and increases the power of theta activity. Conclusions: We suggest that microseizures are modifications of the existent neuronal network within inter-connected microdomains, and bursting neurons could act as a kindling-like mechanism that synchronizes HFOs with other microdomains. The NPD1 bioactivity in epileptogenesis suggests protection of neuronal circuitry at the post synaptic levels. Supported by: NIH P20RR016816. Disclosure: Dr. Musto has nothing to disclose. Dr. Khoobehi has nothing to disclose. Dr. Walker has nothing to disclose. Dr. Bazan has nothing to disclose.

Mitochondrial signaling contributes to disuse muscle atrophy

It is well established that long durations of bed rest, limb immobilization, or reduced activity in respiratory muscles during mechanical ventilation results in skeletal muscle atrophy in humans and other animals. The idea that mitochondrial damage/dysfunction contributes to disuse muscle atrophy originated over 40 years ago. These early studies were largely descriptive and did not provide unequivocal evidence that mitochondria play a primary role in disuse muscle atrophy. However, recent experiments have provided direct evidence connecting mitochondrial dysfunction to muscle atrophy. Numerous studies have described changes in mitochondria shape, number, and function in skeletal muscles exposed to prolonged periods of inactivity. Furthermore, recent evidence indicates that increased mitochondrial ROS production plays a key signaling role in both immobilization-induced limb muscle atrophy and diaphragmatic atrophy occurring during prolonged mechanical ventilation. Moreover, new evidence reveals that, during denervation-induced muscle atrophy, increased mitochondrial fragmentation due to fission is a required signaling event that activates the AMPK-FoxO3 signaling axis, which induces the expression of atrophy genes, protein breakdown, and ultimately muscle atrophy. Collectively, these findings highlight the importance of future research to better understand the mitochondrial signaling mechanisms that contribute to disuse muscle atrophy and to develop novel therapeutic interventions for prevention of inactivity-induced skeletal muscle atrophy.

High Levels of Calsequestrin in Some Snake Muscles. Why?

Calsequestrin (CSQ) is the most abundant Ca2+ binding protein in sarcoplasmic reticulum (SR) of skeletal and cardiac muscle. It is characterized by a high capacity and a moderate affinity for Ca2+ and thus it maintains luminal free Ca2+ in the junctional SR cisternae (jSR) at the physiological concentration of 1mM, while storing up to 20mM total calcium. Thin-section TEMs of superficial epaxial muscles from Nerodia sipedon and Boa constrictor show at least two structurally distinguishable types of fibers, probably twitch and tonic. Twitch fibers have unusually wide jSR cisternae completely filled with a finely granular matrix of CSQ polymers. The visible luminal content also extends far from the triads into the longitudinal SR. This is also the case in anterior intermandibular muscles from the same snakes. The percentage of fiber volume occupied by SR in twitch fibers from superficial epaxial muscles was calculated, from morphometry of thin sections, to be 9.5% in Nerodia, 10.6% in Boa and 7.5% in leg muscles from the lizard Anolis carolinensis, another lepidosaur. Comparable data from the literature for mouse indicate 5.5% in EDL and 2.5% in soleus. So, overall, the snake muscles have considerably higher Ca2+ storage capacity than lizard and mouse, two species that move frequently. We suggest that this may be related to prolonged periods of inactivity of these snakes, interrupted by the very infrequent use of muscles during prey capture and locomotion.Supported by NIH HL048093 (CFA)

Mitochondrial-targeted antioxidants protect skeletal muscle against immobilization-induced muscle atrophy

Prolonged periods of muscular inactivity (e.g., limb immobilization) result in skeletal muscle atrophy. Although it is established that reactive oxygen species (ROS) play a role in inactivity-induced skeletal muscle atrophy, the cellular pathway(s) responsible for inactivity-induced ROS production remain(s) unclear. To investigate this important issue, we tested the hypothesis that elevated mitochondrial ROS production contributes to immobilization-induced increases in oxidative stress, protease activation, and myofiber atrophy in skeletal muscle. Cause-and-effect was determined by administration of a novel mitochondrial-targeted antioxidant (SS-31) to prevent immobilization-induced mitochondrial ROS production in skeletal muscle fibers. Compared with ambulatory controls, 14 days of muscle immobilization resulted in significant muscle atrophy, along with increased mitochondrial ROS production, muscle oxidative damage, and protease activation. Importantly, treatment with a mitochondrial-targeted antioxidant attenuated the inactivity-induced increase in mitochondrial ROS production and prevented oxidative stress, protease activation, and myofiber atrophy. These results support the hypothesis that redox disturbances contribute to immobilization-induced skeletal muscle atrophy and that mitochondria are an important source of ROS production in muscle fibers during prolonged periods of inactivity.

Exercise for preventing and treating osteoporosis in postmenopausal women

Osteoporosis is a condition resulting in an increased risk of skeletal fractures due to a reduction in the density of bone tissue. Treatment of osteoporosis typically involves the use of pharmacological agents. In general it is thought that disuse (prolonged periods of inactivity) and unloading of the skeleton promotes reduced bone mass, whereas mechanical loading through exercise increases bone mass. To examine the effectiveness of exercise interventions in preventing bone loss and fractures in postmenopausal women. During the update of this review we updated the original search strategy by searching up to December 2010 the following electronic databases: the Cochrane Musculoskeletal Group's Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2010 Issue 12); MEDLINE; EMBASE; HealthSTAR; Sports Discus; CINAHL; PEDro; Web of Science; Controlled Clinical Trials; and AMED. We attempted to identify other studies by contacting experts, searching reference lists and searching trial registers. All randomised controlled trials (RCTs) that met our predetermined inclusion criteria. Pairs of members of the review team extracted the data and assessed trial quality using predetermined forms. For dichotomous outcomes (fractures), we calculated risk ratios (RRs) using a fixed-effect model. For continuous data, we calculated mean differences (MDs) of the percentage change from baseline. Where heterogeneity existed (determined by the I(2) statistic), we used a random-effects model. Forty-three RCTs (27 new in this update) with 4320 participants met the inclusion criteria. The most effective type of exercise intervention on bone mineral density (BMD) for the neck of femur appears to be non-weight bearing high force exercise such as progressive resistance strength training for the lower limbs (MD 1.03; 95% confidence interval (CI) 0.24 to 1.82). The most effective intervention for BMD at the spine was combination exercise programmes (MD 3.22; 95% CI 1.80 to 4.64) compared with control groups. Fractures and falls were reported as adverse events in some studies. There was no effect on numbers of fractures (odds ratio (OR) 0.61; 95% CI 0.23 to 1.64). Overall, the quality of the reporting of studies in the meta-analyses was low, in particular in the areas of sequence generation, allocation concealment, blinding and loss to follow-up. Our results suggest a relatively small statistically significant, but possibly important, effect of exercise on bone density compared with control groups. Exercise has the potential to be a safe and effective way to avert bone loss in postmenopausal women.

Sports Hernia

Groin injuries are a common occurrence in elite-level athletes. These injuries can cause significant pain and disability, leading to prolonged periods of inactivity and consternation among athletes, coaches, athletic trainers, and physicians alike. The differential diagnosis for groin pain is vast and spans multiple disciplines, including orthopaedics, general surgery, urology, gynecology, and neurology. Sports hernias are one cause of chronic groin pain in athletes and are distinct entities from classic hernias. They are often caused by a deficient posterior wall of the inguinal canal, but may also involve concurrent injuries, such as conjoint and adductor tendinopathies and nerve entrapment. Understanding the complex lower abdominal, pelvic, and hip anatomy and pathophysiology of sports hernias is crucial to making an accurate diagnosis and providing appropriate treatment options. Newer, less invasive surgical repair techniques show promising early results in improving pain and decreasing recovery time.

Mitochondrial‐targeted antioxidants attenuate immobilization‐induced skeletal muscle atrophy

Prolonged periods of muscular inactivity (e.g., limb immobilization) result in skeletal muscle atrophy. Although is established that reactive oxygen species (ROS) play a role in inactivity‐induced skeletal muscle atrophy, the pathway(s) responsible for inactivity‐induced ROS production remain unclear. To investigate this important issue we tested the hypothesis that elevated mitochondrial ROS emission is essential for immobilization‐induced increases in oxidative stress and proteolysis in skeletal muscle. Cause and effect was determined by administering a novel mitochondrial‐targeted antioxidant (SS‐31) to prevent immobilization‐induced mitochondrial ROS emission in skeletal muscle fibers. Compared to ambulatory controls, 14‐days of immobilization resulted in decreased skeletal muscle mass along with increased mitochondrial ROS production, muscle oxidative damage, and protease activation. Importantly, treatment with SS‐31 attenuated the inactivity‐induced increase in mitochondrial ROS emission and prevented oxidative stress, protease activation, and fiber atrophy. These results support the hypothesis that redox disturbances are required for immobilization‐induced skeletal muscle atrophy and that mitochondria are a major source of ROS production in muscle fibers during prolonged periods of inactivity. Supported by NIH R01 HL087839 awarded to SKP

Youth and Adolescent Physical Activity Lapsers

The present study examined whether self-efficacy mediates the relationship between family social influence and physical activity among youth who have experienced a recent lapse in their physical activity participation. Using a prospective, longitudinal design, participants completed measures of social influence, self-regulatory efficacy and physical activity. Only those participants whose physical activity declined were retained for further analysis. Self-regulatory efficacy partially mediated the relationship between family social influence and physical activity, with self-efficacy mediating 36 percent of the total effect. The results provide support for self-regulatory efficacy as a mediator and provide preliminary insight into the potential mechanisms for preventing lapses in activity from developing into prolonged periods of inactivity within this population.

RESISTANCE TO DEHYDRATION BETWEEN BOUTS OF BLOOD FEEDING IN THE BED BUG, CIMEX LECTULARIUS, IS ENHANCED BY WATER CONSERVATION, AGGREGATION, AND QUIESCENCE

To determine how the bed bug, Cimex lectularius, survives in a dry environment for many months without feeding, water-balance characteristics were compared for all stages from first-instar nymphs to adults. This species is characterized by a low net transpiration rate averaging < 0.2%/h, high tolerance for dehydration (30-40% loss in body water), and an impermeable cuticle as indicated by a high critical transition temperature (CTT) in the 35-40 degrees C range, implying that this insect is adapted for desiccation-hardiness. The capacity of adults to survive for 2 weeks at 0.00a(v) (a(v) = % RH/100) with no access to food or water exemplifies this trait. In contrast to more mature stages, first-instar nymphs contain more water, lose water at a faster rate, experience abrupt water loss at a lower temperature, and survive less time in dry air, suggesting that this stage is the most sensitive to water stress. This insect relies on blood to replenish water stores; none of the stages examined have the capacity to absorb water vapor (critical equilibrium activity, CEA > or = 0.99a(v)), and they drank only sparingly when offered free water. As the bed bugs progress through their development, they gradually reduce their water requirements while increasing their desiccation resistance. Surviving water stress is considerably enhanced behaviorally by quiescence, characterized by prolonged periods of inactivity, and by the formation of clusters that generate a water-conserving group effect.

Features of great minima in solar activity during the last 1000 years

Deep minima in solar activity, the so-called “reat minima” or “rand minima” occurred several times during the last 1000 years. Such prolonged periods of inactivity are confirmed by the past solar activity recorded in sunspot and auroral observations or tree rings and ice cores. These records show that such deep minima are fairly common in the long-term solar behavior, and are expected to occur again in the future. In this paper, we use the sunspot and auroral records of ancient Korea and China, and cosmogenic isotopes to examine the features of great minima in solar activity during the last 1000 years. The existence of great minima is clearly seen in the time distribution of historical data, in agreement with the variation of Δ 14C content that increases during periods of great minima. Also, the sunspot and auroral records indicate that numerous auroral activities existed between the Spörer minimum and the Maunder minimum, and that the Spörer minimum occurred between ∼1410 and ∼1510 implying the duration of ∼100 years. In addition, we find that the longest period of solar inactivity during the last 1000 years occurred during the Spörer minimum where both sunspot and auroral records are scarcest among the great minima.

Effects of 10 days of bedrest on body composition and the rate of muscle protein synthesis in older men and women

The effects of bed rest are well described in younger subjects but have not been evaluated in older adults. The objective of this study was to examine the effects of 10 days of bed rest on body composition changes and muscle protein synthesis in healthy older people. Eight subjects (68 ± 5 yo, M/F: 2/6) remained in bed, except for toileting, for 10 consecutive days. All subjects consumed a eucaloric diet providing 0.8 g protein·kg−1·d−1. Body composition (DEXA), and muscle protein synthesis (24-hr infusion of 13C6-phenylalanine) were assessed before and immediately after bed rest. On average, there was a 7% loss of lower extremity lean tissue in these subjects (14454 g to 13511 g, p<0.05), and the fractional muscle protein synthetic rate declined 44% (n=4, 0.086 %·hr−1 to 0.048 %·hr−1, p<0.05). These results indicate that there is a significant loss of muscle, with a more pronounced decline in muscle protein synthesis as a result of 10 days of bed rest. This loss of muscle in these older people after 10 days is greater than that seen in previous studies in young subjects after 28 days of bed rest. These data are of particular significance given the number of older adults that experience prolonged bed rest during hospitalization or institutionalization. Prophylactic measures to prevent loss of skeletal muscle in elderly people during prolonged periods of inactivity should be given a high priority. NIH PO1 AG023591, M01 RR14288