318 research outputs found
Selection-rule blockade and rectification in quantum heat transport
We introduce a new thermal transport phenomenon, a unidirectional
selection-rule blockade, and show how it produces unprecedented rectification
of bosonic heat flow through molecular or mesoscopic quantum systems.
Rectification arises from the quantization of energy levels of the conduction
element and selection rules of reservoir coupling operators. The simplest
system exhibiting the selection-rule blockade is an appropriately coupled
three-level system, providing a candidate for a high-performance heat diode. We
present an analytical treatment of the transport problem and discuss how the
phenomenon generalizes to multilevel systems.Comment: 4 pages, 3 Fig
Photon heat transport in low-dimensional nanostructures
At low temperatures when the phonon modes are effectively frozen, photon
transport is the dominating mechanism of thermal relaxation in metallic
systems. Starting from a microscopic many-body Hamiltonian, we develop a
nonequilibrium Green's function method to study energy transport by photons in
nanostructures. A formally exact expression for the energy current between a
metallic island and a one-dimensional electromagnetic field is obtained. From
this expression we derive the quantized thermal conductance as well as show how
the results can be generalized to nonequilibrium situations. Generally, the
frequency-dependent current noise of the island electrons determines the energy
transfer rate.Comment: 4 pages, 3 Fig
Detection of aphid migrations in Finland
Our insect immigration warning system was built on the atmospheric dispersion model that has been used in predicting long-range transport of airborne pollen. We observed immigrations with a trap network consisting of rotating tow-nets, yellow sticky traps, and suction traps.
Based on our studies the aphids can be detected with radars when they occur in large numbers
Physiological and physical performance changes during a 20-day winter military training course and its subsequent 10-day recovery period
The present study investigated physiological, mental and physical performance changes during
a 20-day winter military training course and the following 10-day recovery period. Fifty-eight (age
19 ± 1 years, height 182 ± 6 cm, body mass 78.5 ± 7.2 kg) male soldiers volunteered. Body compo sition, serum biomarker levels and performance tests were measured four times during the study.
In addition, questionnaires were collected daily for subjective stress and rate of perceived
exertion. The course induced significant declines in body (−3.9%, p < 0.05) and fat mass
(−31.6%, p < 0.05) as well as in all assessed physical performance variables (−9.2 - −20.2%, p <
0.05), testosterone (−73.7%, p < 0.001) and IGF-1 concentrations (−43.6%, p < 0.001). At the same
time, the sex hormone-binding globulin, creatine kinase, and C-reactive protein values increased
significantly (46.3–1952.7%, p < 0.05). After the 10-day recovery period, the body composition and
hormonal values returned to the baseline (p < 0.05), as did some physical performance variables,
such as 2 min sit-ups and the evacuation test (p < 0.05). However, explosive force production in
the upper and lower bodies remained unrecovered. The 20-day winter military training caused
significant physiological and mental stress, as well as a drastic decline in physical performance
even for highly physically fit soldiers, and the 10-day recovery period did not establish full
recovery
Equivalent qubit dynamics under classical and quantum noise
We study the dynamics of quantum systems under classical and quantum noise,
focusing on decoherence in qubit systems. Classical noise is described by a
random process leading to a stochastic temporal evolution of a closed quantum
system, whereas quantum noise originates from the coupling of the microscopic
quantum system to its macroscopic environment. We derive deterministic master
equations describing the average evolution of the quantum system under
classical continuous-time Markovian noise and two sets of master equations
under quantum noise. Strikingly, these three equations of motion are shown to
be equivalent in the case of classical random telegraph noise and proper
quantum environments. Hence fully quantum-mechanical models within the Born
approximation can be mapped to a quantum system under classical noise.
Furthermore, we apply the derived equations together with pulse optimization
techniques to achieve high-fidelity one-qubit operations under random telegraph
noise, and hence fight decoherence in these systems of great practical
interest.Comment: 5 pages, 2 figures; converted to PRA format, added Fig. 2, corrected
typo
Ecological and genetic basis of metapopulation persistence of the Glanville fritillary butterfly in fragmented landscapes
Ecologists are challenged to construct models of the biological consequences of habitat loss and fragmentation. Here, we use a metapopulation model to predict the distribution of the Glanville fritillary butterfly during 22 years across a large heterogeneous landscape with 4,415 small dry meadows. The majority (74%) of the 125 networks into which the meadows were clustered are below the extinction threshold for long-term persistence. Among the 33 networks above the threshold, spatial configuration and habitat quality rather than the pooled habitat area predict metapopulation size and persistence, but additionally allelic variation in a SNP in the gene Phosphoglucose isomerase (Pgi) explains 30% of variation in metapopulation size. The Pgi genotypes are associated with dispersal rate and hence with colonizations and extinctions. Associations between Pgi genotypes, population turnover and metapopulation size reflect eco-evolutionary dynamics, which may be a common feature in species inhabiting patch networks with unstable local dynamics.Peer reviewe
High-Intensity Functional Training Induces Superior Training Adaptations Compared With Traditional Military Physical Training
This study examined the effectiveness of concurrent strength and endurance training with an emphasis on high-intensity functional training (HIFT) during military service. Voluntary male conscripts (aged 18-28 years) were placed in either an experimental (EXP: n = 50-66) or a control (CON: n = 50-67) group. The training for the EXP group included HIFT using body mass, sandbags, and kettlebells. The CON group trained according to the current practice. Physical performance and body composition were assessed at baseline (PRE), at week 10 (MID), and after (POST) the 19-week training period. Significance was set at p < 0.05. The total distance covered in a 12-minute running test increased in both groups, but the change in EXP was superior to the change in CON (11.6%, ES: 0.79 vs. 5.7%, ES: 0.33; p = 0.027). Maximal strength and power characteristics increased in EXP (3.1-5.0%), whereas no improvements were observed in CON. Conscripts with the highest initial fitness showed no improvements in physical performance in either group. Body mass and waist circumference decreased in EXP, whereas CON showed an increase in muscle mass. These findings suggest that HIFT is an effective and time-efficient approach to improve soldiers' aerobic fitness during military service. For the optimal development of strength, the training equipment used may not have provided sufficient and progressive loading to yield considerable strength adaptations. More focus should be placed on sufficient intensity and volume in both strength and endurance training, especially for the most fit soldiers
Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training
Severe energy deficit may impair hormonal regulation and physical performance in military trainings. The aim of this study was to examine the associations between energy intake, expenditure, and balance, hormones and military performance during a winter survival training. Two groups were studied: the FEX group (n = 46) had 8-day garrison and field training, whereas the RECO group (n = 26) had a 36-h recovery period after the 6-day garrison and field training phase. Energy intake was assessed by food diaries, expenditure via heart rate variability, body composition by bioimpedance, and hormones by blood samples. Strength, endurance and shooting tests were done for evaluating military performance. PRE 0 d, MID 6 d, POST 8 d measurements were carried out. Energy balance was negative in PRE and MID (FEX −1070 ± 866, −4323 ± 1515; RECO −1427 ± 1200, −4635 ± 1742 kcal·d−1). In POST, energy balance differed between the groups (FEX −4222 ± 1815; RECO −608 ± 1107 kcal·d−1 (p < 0.001)), as well as leptin, testosterone/cortisol ratio, and endurance performance (p = 0.003, p < 0.001, p = 0.003, respectively). Changes in energy intake and expenditure were partially associated with changes in leptin and the testosterone/cortisol ratio, but not with physical performance variables. The 36-h recovery restored energy balance and hormonal status after strenuous military training, but these outcomes were not associated with strength or shooting performance
Measurements of CO2 exchange with an automated chamber system throughout the year: challenges in measuring night-time respiration on porous peat soil
Peer reviewe
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