Quantum, cyclic and particle-exchange heat engines

Differences between the thermodynamic behavior of the three-level amplifier (a quantum heat engine based on a thermally pumped laser) and the classical Carnot cycle are usually attributed to the essentially quantum or discrete nature of the former. Here we provide examples of a number of classical and semiclassical heat engines, such as thermionic, thermoelectric and photovoltaic devices, which all utilize the same thermodynamic mechanism for achieving reversibility as the three-level amplifier, namely isentropic (but non-isothermal) particle transfer between hot and cold reservoirs. This mechanism is distinct from the isothermal heat transfer required to achieve reversibility in cyclic engines such as the Carnot, Otto or Brayton cycles. We point out that some of the qualitative differences previously uncovered between the three-level amplifier and the Carnot cycle may be attributed to the fact that they are not the same 'type' of heat engine, rather than to the quantum nature of the three-level amplifier per se.Comment: 9 pages. Proceedings of 'Frontiers of Quantum and Mesoscopic Thermodynamics', Prague 200

Time-independent approximations for periodically driven systems with friction

The classical dynamics of a particle that is driven by a rapidly oscillating potential (with frequency $\omega$) is studied. The motion is separated into a slow part and a fast part that oscillates around the slow part. The motion of the slow part is found to be described by a time-independent equation that is derived as an expansion in orders of $\omega^{-1}$ (in this paper terms to the order $\omega^{-3}$ are calculated explicitly). This time-independent equation is used to calculate the attracting fixed points and their basins of attraction. The results are found to be in excellent agreement with numerical solutions of the original time-dependent problem.Comment: 5 pages, 4 figures. Revised version. Minor change

Adaptive Models for Gene Networks

Biological systems are often treated as time-invariant by computational models that use fixed parameter values. In this study, we demonstrate that the behavior of the p53-MDM2 gene network in individual cells can be tracked using adaptive filtering algorithms and the resulting time-variant models can approximate experimental measurements more accurately than time-invariant models. Adaptive models with time-variant parameters can help reduce modeling complexity and can more realistically represent biological systems

beta-alanine supplementation improves tactical performance but not cognitive function in combat soldiers

Background: There are no known studies that have examined beta-alanine supplementation in military personnel. Considering the physiological and potential neurological effects that have been reported during sustained military operations, it appears that beta-alanine supplementation may have a potential benefit in maintaining physical and cognitive performance during high-intensity military activity under stressful conditions. The purpose of this study was to examine the effect of 28 days of beta-alanine ingestion in military personnel while fatigued on physical and cognitive performance. Methods: Twenty soldiers (20.1 +/- 0.9 years) from an elite combat unit were randomly assigned to either a beta-alanine ( BA) or placebo (PL) group. Soldiers were involved in advanced military training, including combat skill development, navigational training, self-defense/hand-to-hand combat and conditioning. All participants performed a 4-km run, 5-countermovement jumps using a linear position transducer, 120-m sprint, a 10-shot shooting protocol with assault rifle, including overcoming a misfire, and a 2-min serial subtraction test to assess cognitive function before (Pre) and after ( Post) 28 days of supplementation. Results: The training routine resulted in significant increases in 4-km run time for both groups, but no between group differences were seen (p = 0.597). Peak jump power at Post was greater for BA than PL (p = 0.034), while mean jump power for BA at Post was 10.2% greater (p = 0.139) than PL. BA had a significantly greater (p = 0.012) number of shots on target at Post (8.2 +/- 1.0) than PL (6.5 +/- 2.1), and their target engagement speed at Post was also significantly faster (p = 0.039). No difference in serial subtraction performance was seen between the groups (p = 0.844). Conclusion: Results of this study indicate that 4-weeks of beta-alanine ingestion in young, healthy soldiers did not impact cognitive performance, but did enhance power performance, marksmanship and target engagement speed from pre-ingestion levels

Land/Homeland, Story/History: the social landscapes of the Southern Levant from Alexander to Augustus

This material has been published in revised form in The Social Archaeology of the Levant from Prehistory to the Present edited by Assaf Yasur-Landau, Eric H. Cline, and Yorke Rowan https://doi.org/10.1017/9781316661468.024. This version is free to view and download for private research and study only. Not for re-distribution or re-use. © Cambridge University PressThe Hellenistic era opens with Alexander the Great’s triumph over Achaemenid Persia, an event that inaugurates a millennium of western political hegemony over the Levant and paves the way for an infusion of western cultural ideas. I examine the social repercussions of this juncture of politics and culture for five self-identifying ethnoi within the region: Phoenicians (meaning Tyrians and Sidonians), Samaritans, Judeans, Idumeans, and Nabateans. I consider physical and written evidence as reflections of agency, opportunity, status, and authority, in order to reconstruct how people defined and presented themselves, and how they jockeyed for position and security in a crowded region and a volatile world. Fortunes fluctuated along with changes in imperial rule. The Ptolemies instituted a rapacious system of resource extraction, under which only the most nimble or removed kept their footing (i.e., Phoenicians, Nabateans). The Seleucids followed in the more magnanimous footsteps of the Achaemenids, offering a measure of economic and legal autonomy, an approach that placated some (e.g., Samaritans) and empowered others (e.g., Judeans). As Seleucid control weakened, groups used various means to claim status and authority. Samaritans, Judeans, and Idumeans deployed history and geography; Phoenicians and Nabateans depended on economic connections and cultural currency. Waning imperial powers in the later second century BCE left the region’s ethnoi effectively autonomous. Phoenicians and Nabateans became wealthy cosmopolitans connected to Mediterranean markets. Judeans unleashed an aggressive program of territorial acquisition, first successfully against Idumeans and Samaritans, then less so against Tyrians and Nabateans. Contemporary writers turned these events into historical narratives – divinely countenanced (1 Maccabees, Dead Sea Scrolls) vs. opportunistic circumstance (2 Maccabees, Tacitus, Josephus). These accounts offered people differing templates by which to situate themselves in place and history – templates ill-suited for co-existence. By the time Roman authorities established their imperial presence here in the mid-first century BCE, the social landscape was mined and ready to erupt.Accepted manuscrip

Β-Alanine Ingestion Increases Muscle Carnosine Content And Combat Specific Performance In Soldiers

The purpose of this study was to examine the effect of β-alanine (BA) ingestion on tissue carnosine levels and the impact such changes would have on combat specific activity. Eighteen soldiers (19.9 ± 0.8 year) from an elite combat unit were randomly assigned to either a BA or placebo (PL) group. Before and following a 30-day supplementation period carnosine content of the gastrocnemius muscle and brain was determined by proton magnetic resonance spectroscopy. During each testing session, participants performed military relevant tasks that included a 2.5 km run, a 1-min sprint, 50-m casualty carry, repeated 30-m sprints with target shooting, and a 2-min serial subtraction test (SST) to assess cognitive function under stressful conditions. A significant elevation (p = 0.048) in muscle carnosine content was noted in BA compared to PL. Changes in muscle carnosine content was correlated to changes in fatigue rate (r = 0.633, p = 0.06). No changes (p = 0.607) were observed in brain carnosine content. Following supplementation, no differences were noted in 2.5 km run, 1-min sprint, repeated sprint, or marksmanship performance, but participants in BA significantly (p = 0.044) improved their time for the 50-m casualty carry and increased their performance (p = 0.022) in the SST compared to PL. In summary, 30-days of BA ingestion can increase muscle carnosine content and improve aspects of military specific performance. Although cognitive performance was significantly greater in participants consuming BA compared to placebo, current study methods were unable to detect any change in brain carnosine levels, thus, the precise mechanism underlying these effects remains elusive

Bariatric surgery in patients with type 1 diabetes: special considerations are warranted

Objective: We examined short and long-term outcomes of bariatric surgery in patients with obesity and type 1 diabetes mellitus (T1DM). Methods: We reviewed the records of all adults insured by Maccabi Healthcare Services during 2010 -2015, with body mass index (BMI) ⩾30 kg/m2 and T1DM; and compared weight reduction and glucose control according to the performance of bariatric surgery. BMI and glycated hemoglobin (HbA1c) levels were extracted for baseline and every 6 months, for a mean 3.5 years. Results: Of 52 patients, 26(50%) underwent bariatric surgery. Those who underwent surgery were more often female and with a longer duration of diabetes. Immediately postoperative, 4(15%) developed diabetic ketoacidosis, while 6(23%) experienced severe hypoglycemic episodes. The mean BMI decreased among surgery patients: from 39.5±4.4 to 30.1±5.0 kg/m2 ( p < 0.0001); and increased among those who did not undergo surgery: from 33.6±3.9 to 35.1±4.4 kg/m2 ( p = 0.49). The mean HbA1c level decreased during the first 6 months postoperative: from 8.5±0.9% to 7.9±0.9%; however, at the end of follow-up, was similar to baseline, 8.6±2.0% (p = 0.87). For patients who did not undergo surgery, the mean HbA1c increased from 7.9±1.9% to 8.6±1.5% ( p = 0.09). Conclusions: Among individuals with obesity and T1DM, weight loss was successful after bariatric surgery, but glucose control did not improve. The postoperative risks of diabetic ketoacidosis and severe hypoglycemic episodes should be considering when performing bariatric surgery in this population

beta-alanine supplementation improves tactical performance but not cognitive function in combat soldiers

Background: There are no known studies that have examined beta-alanine supplementation in military personnel. Considering the physiological and potential neurological effects that have been reported during sustained military operations, it appears that beta-alanine supplementation may have a potential benefit in maintaining physical and cognitive performance during high-intensity military activity under stressful conditions. The purpose of this study was to examine the effect of 28 days of beta-alanine ingestion in military personnel while fatigued on physical and cognitive performance. Methods: Twenty soldiers (20.1 +/- 0.9 years) from an elite combat unit were randomly assigned to either a beta-alanine ( BA) or placebo (PL) group. Soldiers were involved in advanced military training, including combat skill development, navigational training, self-defense/hand-to-hand combat and conditioning. All participants performed a 4-km run, 5-countermovement jumps using a linear position transducer, 120-m sprint, a 10-shot shooting protocol with assault rifle, including overcoming a misfire, and a 2-min serial subtraction test to assess cognitive function before (Pre) and after ( Post) 28 days of supplementation. Results: The training routine resulted in significant increases in 4-km run time for both groups, but no between group differences were seen (p = 0.597). Peak jump power at Post was greater for BA than PL (p = 0.034), while mean jump power for BA at Post was 10.2% greater (p = 0.139) than PL. BA had a significantly greater (p = 0.012) number of shots on target at Post (8.2 +/- 1.0) than PL (6.5 +/- 2.1), and their target engagement speed at Post was also significantly faster (p = 0.039). No difference in serial subtraction performance was seen between the groups (p = 0.844). Conclusion: Results of this study indicate that 4-weeks of beta-alanine ingestion in young, healthy soldiers did not impact cognitive performance, but did enhance power performance, marksmanship and target engagement speed from pre-ingestion levels