Insect Cold-Hardiness: Insights from the Arctic

Cold-hardiness and related adaptations of insects in the Arctic correspond to characteristic climatic constraints. Some species are long-lived and are cold-hardy in several stages. In the Arctic, diapause and cold-hardiness are less likely to be linked than in temperate regions, because life-cycle timing depends as much on the need to coincide development with the short summer as on the need to resist winter cold. Winter habitats of many species are exposed rather than sheltered from cold so that development in spring can start earlier. Several features of cold-hardiness in arctic species differ from the characteristics of temperate species: these include very cold-hardy insects with low supercooling points that are not freezing tolerant; freezing-tolerant species that supercool considerably rather than freezing at relatively high subfreezing temperatures; mitochondrial degradation linked with the accumulation of cryoprotectants; and the possibly limited occurrence of thermal hysteresis proteins in winter. Several interesting relationships between cold-hardiness and water have been observed, including different types of dehydration. Winter mortality in arctic insects appear to be relatively low. Adaptations to cold in summer include retention of cold-hardiness, even freezing tolerance; selection of warm sites; and behaviour such as basking that allows elevated body temperatures. Studies especially on the high-arctic moth Gynaephora groenlandica show that various factors including cold-hardiness and other summer and winter constraints dictate the structure of energy budgets and the timing of life cycles. Future work should focus on the biological and climatic differences between arctic and other areas by addressing habitat conditions, life-cycle dynamics, and various aspects of cryoprotectant production at different times of year. Even in the Arctic cold-hardiness is complex and involves many simultaneous adaptations.Key words: cold-hardiness, insects, supercooling, freezing-tolerance, cryoprotectants, metabolism, energy budgets, life cycles, habitat selectionL'endurance au froid et autres adaptations connexes des insectes de l'Arctique correspondent à des contraintes climatiques caractéristiques. Certaines espèces ont une grande longévité et sont résistantes au froid à plusieurs stades. Dans l'Arctique, il est moins probable que la diapause et l'endurance au froid soient reliées que dans les zones tempérées, parce que le cycle de vie dépend autant du besoin de faire coïncider la croissance avec le bref été que du besoin de résister au froid hivernal. Les habitats hivernaux de nombreuses espèces sont exposés au froid plutôt qu'abrités du froid de façon que la croissance débute plus tôt au printemps. Plusieurs caractéristiques de la résistance au froid chez des espèces arctiques diffèrent des caractéristiques des espèces tempérées: les premières comprennent des insectes très résistants au froid ayant des points de surfusion bas qui ne sont pas tolérants au gel; des espèces tolérantes au gel qui manifestent une surfusion considérable plutôt que de geler à des températures relativement hautes sous le point de congélation; la dégradation mitochondriale liée à l'accumulation de cryoprotecteurs; et l'occurrence peut-être limitée de protéines à hystérésis thermique en hiver. On a observé plusieurs rapports intéressants entre la résistance au froid et l'eau, y compris différents types de déshydratation. La mortalité hivernale chez les insectes de l'Arctique semble être relativement basse. Les adaptations au froid en été comprennent le maintien de la résistance au froid, et même de la tolérance au gel; le choix de sites tempérés et le comportement qui consiste à se chauffer au soleil, ce qui permet une élévation des températures du corps. Des études effectuées en particulier sur la noctuelle de l'Extrême-Arctique Gynaephora groenlandica montrent que divers facteurs y compris la résistance au froid et d'autres contraintes estivales et hivernales dictent la structure des bilans énergétiques et le rythme des cycles de vie. De futurs travaux devraient porter sur les différences biologiques et climatiques entre des régions arctiques et d'autres zones en étudiant les conditions de l'habitat, la dynamique des cycles de vie et divers aspects de la production de cryoprotecteurs à différentes époques de l'année. Même dans l'Arctique, la résistance au froid est complexe et implique bien des adaptations simultanées.Mots clés: résistance au froid, insectes, surfusion, tolérance au gel, cryoprotecteurs, métabolisme, bilans énergétiques, cycles de vie, sélection de l’habita

Semiclassical Approximation to Neutron Star Superfluidity Corrected for Proximity Effects

The inner crust of a neutron star is a superfluid and inhomogeneous system, consisting of a lattice of nuclei immersed in a sea of neutrons. We perform a quantum calculation of the associated pairing gap and compare it to the results one obtains in the Local Density Approximation (LDA). It is found that the LDA overestimates the spatial dependence of the gap, and leads to a specific heat of the system which is too large at low temperatures, as compared with the quantal result. This is caused by the neglect of proximity effects and the delocalized character of the single-particle wavefunctions close to the Fermi energy. It is possible to introduce an alternative, simple semiclassical approximation of the pairing gap which leads to a specific heat that is in good agreement with the quantum calculation.Comment: RevteX, 8 Postscript Figure

Generator Coordinate Calculations for the Breathing-Mode Giant Monopole Resonance in Relativistic Mean Field Theory

The breathing-mode giant monopole resonance (GMR) is studied within the framework of the relativistic mean-field theory using the Generator Coordinate Method (GCM). The constrained incompressibility and the excitation energy of isoscalar giant monopole states are obtained for finite nuclei with various sets of Lagrangian parameters. A comparison is made with the results of nonrelativistic constrained Skyrme Hartree-Fock calculations and with those from Skyrme RPA calculations. In the RMF theory the GCM calculations give a transition density for the breathing mode, which resembles much that obtained from the Skyrme HF+RPA approach and also that from the scaling mode of the GMR. From the systematic study of the breathing-mode as a function of the incompressibility in GCM, it is shown that the GCM succeeds in describing the GMR energies in nuclei and that the empirical breathing-mode energies of heavy nuclei can be reproduced by forces with an incompressibility close to $K = 300$ MeV in the RMF theory.Comment: 27 pages (Revtex) and 5 figures (available upon request), Preprint MPA-793 (March 1994

Behavior of the giant-dipole resonance in 120^{120}Sn and 208^{208}Pb at high excitation energ

The properties of the giant-dipole resonance (GDR) are calculated as a function of excitation energy, angular momentum, and the compound nucleus particle decay width in the nuclei $^{120}$Sn and $^{208}$Pb, and are compared with recent experimental data. Differences observed in the behavior of the full-width-at-half-maximum of the GDR for $^{120}$Sn and $^{208}$Pb are attributed to the fact that shell corrections in $^{208}$Pb are stronger than in $^{120}$Sn, and favor the spherical shape at low temperatures. The effects shell corrections have on both the free energy and the moments of inertia are discussed in detail. At high temperature, the FWHM in $^{120}$Sn exhibits effects due to the evaporation width of the compound nucleus, while these effects are predicted for $^{208}$Pb.Comment: 28 pages in RevTeX plus eight postscript figures. Submitted to Nucl. Phys.

Shell Model for Warm Rotating Nuclei

In order to provide a microscopic description of levels and E2 transitions in rapidly rotating nuclei with internal excitation energy up to a few MeV, use is made of a shell model which combines the cranked Nilsson mean-field and the residual surface delta two-body force. The damping of collective rotational motion is investigated in the case of a typical rare-earth nucleus, namely \Yb. It is found that rotational damping sets in at around 0.8 MeV above the yrast line, and the levels which form rotational band structures are thus limited. We predict at a given rotational frequency existence of about 30 rotational bands of various lengths, in overall agreement with the experimental findings. The onset of the rotational damping proceeds quite gradually as a function of the internal excitation energy. The transition region extends up to around 2 MeV above yrast and it is characterized by the presence of scars of discrete rotational bands which extend over few spin values and stand out among the damped transitions, and by a two-component profile in the $E_\gamma -E_\gamma$ correlation. The important role played by the high-multipole components of the two-body residual interaction is emphasized.Comment: 28 pages, LaTe

Interferon alfa for chronic hepatitis B infection: Increased efficacy of prolonged treatment

Interferon alfa (IFN-a) is the primary treatment for chronic hepatitis B. The standard duration of IFN-a therapy is considered 16 weeks; however, the optimal treatment length is still poorly defined. We evaluated the efficacy and acceptability of prolonged IFN-a treatment in patients with chronic hepatitis B. To investigate whether treatment prolongation could enhance the rate of hepatitis B e antigen (HBeAg) seroconversion, we conducted a prospective, controlled, multicenter trial in wh

Vortex-nucleus interaction in the inner crust of neutron stars

The structure of a vortex in the inner crust of neutron stars is calculated within the framework of quantum mean field theory taking into account the interaction with the nuclei composing the Coulomb lattice. Making use of the results obtained with different nuclear interactions, the pinning energy, relevant in the study of glitches, is worked out. Quantal size and density dependent effects are found to be important

Nuclear Alpha-Particle Condensates

The $\alpha$-particle condensate in nuclei is a novel state described by a product state of $\alpha$'s, all with their c.o.m. in the lowest 0S orbit. We demonstrate that a typical $\alpha$-particle condensate is the Hoyle state ($E_{x}=7.65$ MeV, $0^+_2$ state in $^{12}$C), which plays a crucial role for the synthesis of $^{12}$C in the universe. The influence of antisymmentrization in the Hoyle state on the bosonic character of the $\alpha$ particle is discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle state, therefore, are predominant. It is conjectured that $\alpha$-particle condensate states also exist in heavier $n\alpha$ nuclei, like $^{16}$O, $^{20}$Ne, etc. For instance the $0^+_6$ state of $^{16}$O at $E_{x}=15.1$ MeV is identified from a theoretical analysis as being a strong candidate of a $4\alpha$ condensate. The calculated small width (34 keV) of $0^+_6$, consistent with data, lends credit to the existence of heavier Hoyle-analogue states. In non-self-conjugated nuclei such as $^{11}$B and $^{13}$C, we discuss candidates for the product states of clusters, composed of $\alpha$'s, triton's, and neutrons etc. The relationship of $\alpha$-particle condensation in finite nuclei to quartetting in symmetric nuclear matter is investigated with the help of an in-medium modified four-nucleon equation. A nonlinear order parameter equation for quartet condensation is derived and solved for $\alpha$ particle condensation in infinite nuclear matter. The strong qualitative difference with the pairing case is pointed out.Comment: 71 pages, 41 figures, review article, to be published in "Cluster in Nuclei (Lecture Notes in Physics) - Vol.2 -", ed. by C. Beck, (Springer-Verlag, Berlin, 2011

Pleiotropic associations of heterozygosity for the SERPINA1 Z allele in the UK Biobank

Homozygosity for the SERPINA1 Z allele causes α1-antitrypsin deficiency, a rare condition that can cause lung and liver disease. However, the effects of Z allele heterozygosity on nonrespiratory phenotypes, and on lung function in the general population, remain unclear. We conducted a large, population-based study to determine Z allele effects on >2400 phenotypes in the UK Biobank (N=303 353). Z allele heterozygosity was strongly associated with increased height (β=1.02 cm, p=3.91×10−68), and with other nonrespiratory phenotypes including increased risk of gall bladder disease, reduced risk of heart disease and lower blood pressure, reduced risk of osteoarthritis and reduced bone mineral density, increased risk of headache and enlarged prostate, as well as with blood biomarkers of liver function. Heterozygosity was associated with higher height-adjusted forced expiratory volume in 1 s (FEV1) (β=19.36 mL, p=9.21×10−4) and FEV1/forced vital capacity (β=0.0031, p=1.22×10−5) in nonsmokers, whereas in smokers, this protective effect was abolished. Furthermore, we show for the first time that sex modifies the association of the Z allele on lung function. We conclude that Z allele heterozygosity and homozygosity exhibit opposing effects on lung function in the UK population, and that these associations are modified by smoking and sex. In exploratory analyses, heterozygosity for the Z allele also showed pleiotropic associations with nonrespiratory health-related traits and disease risk