Reversible self-assembly of patchy particles into monodisperse icosahedral clusters

We systematically study the design of simple patchy sphere models that reversibly self-assemble into monodisperse icosahedral clusters. We find that the optimal patch width is a compromise between structural specificity (the patches must be narrow enough to energetically select the desired clusters) and kinetic accessibility (they must be sufficiently wide to avoid kinetic traps). Similarly, for good yields the temperature must be low enough for the clusters to be thermodynamically stable, but the clusters must also have enough thermal energy to allow incorrectly formed bonds to be broken. Ordered clusters can form through a number of different dynamic pathways, including direct nucleation and indirect pathways involving large disordered intermediates. The latter pathway is related to a reentrant liquid-to-gas transition that occurs for intermediate patch widths upon lowering the temperature. We also find that the assembly process is robust to inaccurate patch placement up to a certain threshold, and that it is possible to replace the five discrete patches with a single ring patch with no significant loss in yield.Comment: 12 pages, 12 figure

Two New Species and Temporal Changes in the Prevalence of Eimerians in a Free-Living Population of Townsend\u27s Ground Squirrels (\u3ci\u3eSpermophilus townsendii\u3c/i\u3e) in Idaho

More than 1,180 fecal samples were collected from 253 juvenile and 384 adult Townsend\u27s ground squirrels (Spermophilus townsendii) at the Snae Snake River Birds of Prey Area near Boise, Idaho, from February to June 1992. Oocysts of 7 eimerians were observed. Five are new host records (Eimeria beecheyi, Eimeria bilamellata, Eimeria callospermophili, Eimeria lateralis, and Eimeria morainensis), 2 species are described here as new, and new structural information on E. morainensis is added. Sporulated oocysts of Eimeria adaensis n. sp. are ovoidal, 19.6 x 22.7 (16-22 x 18-26) μm with sporocysts ellipsoidal 7.2 x 11.9 (6-10 x 9-15) μm. No micropyle or oocyst residuum, but polar bodies, Stieda bodies, and sporocyst residua are present. Sporulated oocysts of Eimeria pseudospermophili n. sp. are ovoidal, 24.7 x 28.5 (21-27 x 25-32) μm with sporocysts ellipsoidal 8.8 x 14.2 (8-10 x 12-17) μm. Micropyle and oocyst residuum are absent, but polar bodies and Stieda bodies are present. Sporulated oocysts of E. morainensis are more variable in size and shape than originally described and contain 2 distinctly different residua not previously described. Temporal changes in the prevalence of eimerians of all 7 species combined in adult squirrels showed significant decline (r2 = 0.79, P \u3c 0.001). We hypothesize that this decline was due to drought during the period of squirrel activity. No significant temporal change in the prevalence of eimerians in juvenile squirrels was observed. The prevalence of E. callospermophili, E. adaensis, and all eimerians combined in adults was significantly greater than in juveniles. There was no significant difference in eimerian prevalence between male and female squirrels (P \u3c 0.05)

Annual Cycle of Cloud Forcing of Surface Radiation Budget

The climate of the Earth is determined by its balance of radiation. The incoming and outgoing radiation fluxes are strongly modulated by clouds, which are not well understood. The Earth Radiation Budget Experiment (Barkstrom and Smith, 1986) provided data from which the effects of clouds on radiation at the top of the atmosphere (TOA) could be computed (Ramanathan, 1987). At TOA, clouds increase the reflected solar radiation, tending to cool the planet, and decrease the OLR, causing the planet to retain its heat (Ramanathan et al., 1989; Harrison et al., 1990). The effects of clouds on radiation fluxes are denoted cloud forcing. These shortwave and longwave forcings counter each other to various degrees, so that in the tropics the result is a near balance. Over mid and polar latitude oceans, cloud forcing at TOA results in large net loss of radiation. Here, there are large areas of stratus clouds and cloud systems associated with storms. These systems are sensitive to surface temperatures and vary strongly with the annual cycle. During winter, anticyclones form over the continents and move to the oceans during summer. This movement of major cloud systems causes large changes of surface radiation, which in turn drives the surface temperature and sensible and latent heat released to the atmosphere

The Future of Micro-grids in Ecuador

An analysis is made on the development of power lines worldwide and that offer the approaches of the impacts that are generated in the economic and environmental, which justify the application of smart grids in Ecuador, as an effective way to raise the efficiency of the electric power service and to achieve a more efficient use of the energy that is generated by showing the different technologies used in electricity generation where renewable energy sources are incorporated. A comparative analysis of how the installed generation power has been increasing until 2016 is shown

TRH: Pathophysiologic and clinical implications

Thyrotropin releasing hormone is thought to be a tonic stimulator of the pituitary TSH secretion regulating the setpoint of the thyrotrophs to the suppressive effect of thyroid hormones. The peptide stimulates the release of normal and elevated prolactin. ACTH and GH may increase in response to exogenous TRH in pituitary ACTH and GH hypersecretion syndromes and in some extrapituitary diseases. The pathophysiological implications of extrahypothalamic TRH in humans are essentially unknown. The TSH response to TRH is nowadays widely used as a diganostic amplifier in thyroid diseases being suppressed in borderline and overt hyperthyroid states and increased in primary thyroid failure. In hypothyroid states of hypothalamic origin, TSH increases in response to exogenous TRH often with a delayed and/or exaggerated time course. But in patients with pituitary tumors and suprasellar extension TSH may also respond to TRH despite secondary hypothyroidism. This TSH increase may indicate a suprasellar cause for the secondary hypothyroidism, probably due to portal vessel occlusion. The TSH released in these cases is shown to be biologically inactive