Renal Function in Suckling and Fasting Pups of the Northern Elephant Seal

Elephant seals fast for prolonged periods without access to water. This is made possible, in part, by reductions in urine production. However, the mechanisms involved in reducing urine production are not understood. In this study, glomerular filtration rate (GFR) was measured in five northern elephant seal pups (Mirounga angustirostris) via the inulin clearance technique. Measurements were made during day 9 and day 18–22 of nursing and the second and eighth week of the postweaning fast. Plasma aldosterone and cortisol concentrations, quantified by radioimmunoassay, were measured in eight other weanlings during the second and eighth week of the fast. Mean GFR was 79.3±29.3 ml/min during the early suckling period and 78.2±17.1, 89.8±52.7, and 80.4±12.2 ml/min during the late suckling, early fasting and late fasting periods, respectively. Differences between nursing and fasting were insignificant, possibly because reduced protein oxidation during suckling and rapid recruitment of protein for tissue synthesis obviated the need for postprandial hyperfiltration. Alternatively, maintenance of GFR during fasting may facilitate urea concentration by compensating for reductions in the fractional excretion of urea. It is further hypothesized that aldosterone is primarily responsible for mediating renal water reabsorption in this system

Simultaneous Parasitism of Field-Collected Green Cloverworm, \u3ci\u3eHypena Scabra\u3c/i\u3e (Lepidoptera: Noctuidae) Larvae by Endoparasitioids and an Entomopathogenic Fungus

The impacts of entomopathogens (e.g., fungi, bacteria, protists and viruses) on larval Lepidoptera and their associated insect parasitoids have been examined in laboratory studies but field studies of interaction between these two mortality factors are rare. We present field observations of concurrent insect parasitism and fungal disease infection in larvae of the green cloverworm, Hypena scabra, a sporadic pest of soybean (Glycine max) in North America. We reared ten parasitoid species from H. scabra larvae during our three-month study. Three parasitoid species were dominant and overlapped the period of infection by the entomopathogenic fungus Nomuraea rileyi: Aleiodes nolophanae, Cotesia plathypenae and Campylochaeta plathypenae. Two of the three parasitoid species, Co. plathypenae and Ca. plathypenae, completed development within H. scabra larvae infected by N. rileyi. Overall incidence of simultaneous parasitism and fungal infection was low, averaging 6.7% of H. scabra larvae parasitized by Ca. plathypenae and 3.3% of those parasitized by Co. plathypenae

Intrinsic resistivity and the SO(5) theory of high-temperature superconductors

The topological structure of the order parameter in Zhang's SO(5) theory of superconductivity allows for an unusual type of dissipation mechanism via which current-carrying states can decay. The resistivity due to this mechanism, which involves orientation rather than amplitude order-parameter fluctuations, is calculated for the case of a thin superconducting wire. The approach is a suitably modified version of that pioneered by Langer and Ambegaokar for conventional superconductors.Comment: 4 pages, including 1 figure (REVTEX); references added, minor corrections mad

Hormone and Metabolite Changes associated with Extended Breeding Fasts in Male Northern Elephant Seals (Mirounga Angustirostris)

We measured metabolic hormones and several key metabolites in breeding adult male northern elephant seals to examine the regulation of fuel metabolism during extended natural fasts of over 3 months associated with high levels of energy expenditure. Males were sampled twice, early and late in the fast, losing an average of 23% of body mass and 47% of adipose stores between measurements. Males exhibited metabolic homeostasis over the breeding fast with no changes in glucose, non-esterified fatty acids, or blood urea nitrogen. Ketoacids increased over the fast but were very low when compared to other fasting species. Changes within individuals in total triiodothyronine (tT3) were positively related to daily energy expenditure (DEE) and protein catabolism. Differences in levels of thyroid hormones relative to that observed in weaned pups and females suggest a greater deiodination of T4 to support the high DEE of breeding males. Relative levels of leptin and ghrelin were consistent with the suppression of appetite but a significant reduction in growth hormone across the fast was contrary to expectation in fasting mammals. The lack of the increase in cortisol during fasting found in conspecific weaned pups and lactating females may contribute to the ability of breeding males to spare protein despite high levels of energy expenditure. Together these findings reveal significant differences with conspecifics under varying nutrient demands, suggesting metabolic adaptation to extended high energy fasts

Planning for Excellence: Insights from an International Review of Regulators’ Strategic Plans

What constitutes regulatory excellence? Answering this question is an indispensable first step for any public regulatory agency that is measuring, striving towards, and, ultimately, achieving excellence. One useful way to answer this question would be to draw on the broader literature on regulatory design, enforcement, and management. But, perhaps a more authentic way would be to look at how regulators themselves define excellence. However, we actually know remarkably little about how the regulatory officials who are immersed in the task of regulation conceive of their own success. In this Article, we investigate regulators’ definitions of regulatory excellence by drawing on a unique source of data that provides an important window on regulators’ own aspirations: their strategic plans. Strategic plans have been required or voluntarily undertaken for the past decade or longer by regulators around the globe. In these plans, regulators offer mission statements, strategic goals, and measurable and achievable outcomes, all of which indicate what regulators value and are striving to become. Occasionally, they even state explicitly where they have fallen short of “best-in-class” status and how they intend to improve. To date, a voluminous literature exists examining agency practices in strategic planning, but we are aware of no study that tries to glean from the substance of a sizeable number of plans how regulators themselves construe regulatory excellence. The main task of this Article is undertaking this effort. This Article draws on twenty plans from different regulators in nine countries. We found most generally that excellent regulators describe themselves (though not necessarily using exactly these words) as institutions that are more (1) efficient, (2) educative, (3) multiplicative, (4) proportional, (5) vital, (6) just, and (7) honest. In addition to these seven shared attribute categories, our reading of the plans also revealed five other “unusual” attributes that only one or two agencies mentioned. Beyond merely cataloguing the attributes identified by agencies, this Article also discusses commonalities (and differences) between plan structures, emphases, and framings. We found that the plans differed widely in features such as the specificity of their mission statements, the extent to which they emphasized actions over outcomes (or vice versa), and the extent to which commitments were organized along organizational fiefdoms or cut across bureaucratic lines. We urge future scholarship to explore alternative methods of text mining, and to study strategic plans over time within agencies, in order to track how agencies’ notions of regulatory excellence respond to changes in the regulatory context and the larger circumstances within which agencies operate. Looking longitudinally will also shed light on how agencies handle strategic goals that are either met or that prove to be unattainable

Angiotensin II and Aldosterone Increase with Fasting in Breeding Adult Male Northern Elephant Seals (Mirounga angustirostris)

The renin‐angiotensin‐aldosterone system (RAAS) appears to contribute significantly to osmoregulation of fasting northern elephant seal (Mirounga angustirostris) pups; however, RAAS has not been characterized in fasting adult seals. Therefore, this study examined the contribution of RAAS to water turnover rates in fasting adult male northern elephant seals. Blood samples were obtained twice during their breeding fast at an interval of 6.5 wk, and water efflux rate was estimated by isotopic dilution during the same period. Serum electrolytes (Na+, K+, Cl−) and osmolality were unaltered between the two sampling periods, indicating ionic and osmotic homeostasis during the fast. Despite the lack of an increase in vasopressin, serum angiotensin II and aldosterone were increased and were significantly and positively correlated. Changes in aldosterone concentration and water efflux rate were significantly and negatively correlated, suggesting that the greater the increase in aldosterone, the smaller the loss of water. Adult male seals maintain ionic and osmotic homeostasis similar to that of fasting weaned pups, and this homeostasis appears to be mediated, at least in part, by RAAS, which probably contributes to increased water retention as well. The hormonal mechanisms by which northern elephant seals maintain water and electrolyte balance during fasting conditions appear to be similar regardless of age

Topological phases of topological insulator thin films

We study the properties of a thin film of topological insulator material. We treat the coupling between helical states at opposite surfaces of the film in the properly-adapted tunneling approximation, and show that the tunneling matrix element oscillates as function of both the film thickness and the momentum in the plane of the film for Bi$_2$Se$_3$ and Bi$_2$Te$_3$. As a result, while the magnitude of the matrix element at the center of the surface Brillouin Zone gives the gap in the energy spectrum, the sign of the matrix element uniquely determines the topological properties of the film, as demonstrated by explicitly computing the pseudospin textures and the Chern number. We find a sequence of transitions between topological and non-topological phases, separated by semimetallic states, as the film thickness varies. In the topological phase the edge states of the film always exist but only carry a spin current if the edge potentials break particle-hole symmetry. The edge states decay very slowly away from the boundary in Bi$_2$Se$_3$, making Bi$_{2}$Te$_{3}$, where this scale is shorter, a more promising candidate for the observation of these states. Our results hold for free-standing films as well as heterostructures with large-gap insulators

Pairing correlations in a trapped one-dimensional Fermi gas

We use a BCS-type variational wavefunction to study attractively-interacting quasi one-dimensional (1D) fermionic atomic gases, motivated by cold-atom experiments that access the 1D regime using an anisotropic harmonic trapping potential (with trapping frequencies $\omega_x = \omega_y \gg \omega_z$) that confines the gas to a cigar-shaped geometry. To handle the presence of the trap along the $z$-direction, we construct our variational wavefunction from the harmonic oscillator Hermite functions that are the eigenstates of the single-particle problem. Using an analytic determination of the effective interaction among harmonic oscillator states along with a numerical solution of the resulting variational equations, we make specific experimental predictions for how pairing correlations would be revealed in experimental probes like the local density and the momentum correlation function.Comment: 8 pages, 6 figures. Published in Phys. Rev.