University of California

About: University of California is a education organization based out in Oakland, California, United States. It is known for research contribution in the topics: Population & Layer (electronics). The organization has 55175 authors who have published 52933 publications receiving 1491169 citations. The organization is also known as: UC & University of California System.

The frequency, intensity, and diurnal cycle of precipitation in surface and satellite observations over low- and mid-latitudes

Abstract: Global precipitation data sets with high spatial and temporal resolution are needed for many applications, but they were unavailable before the recent creation of several such satellite products. Here, we evaluate four different satellite data sets of hourly or 3-hourly precipitation (namely CMORPH, PERSIANN, TRMM 3B42 and a microwave-only product referred to as MI) by comparing the spatial patterns in seasonal mean precipitation amount, daily precipitation frequency and intensity, and the diurnal and semidiurnal cycles among them and with surface synoptic weather reports. We found that these high-resolution products show spatial patterns in seasonal mean precipitation amount comparable to other monthly products for the low- and mid-latitudes, and the mean daily precipitation frequency and intensity maps are similar among these pure satellite-based precipitation data sets and consistent with the frequency derived using weather reports over land. The satellite data show that spatial variations in mean precipitation amount come largely from precipitation frequency rather than intensity, and that the use of satellite infrared (IR) observations to improve sampling does not change the mean frequency, intensity and the diurnal cycle significantly. Consistent with previous studies, the satellite data show that sub-daily variations in precipitation are dominated by the 24-h cycle, which has an afternoon–evening maximum and mean-to-peak amplitude of 30–100% of the daily mean in precipitation amount over most land areas during summer. Over most oceans, the 24-h harmonic has a peak from midnight to early morning with an amplitude of 10–30% during both winter and summer. These diurnal results are broadly consistent with those based on the weather reports, although the time of maximum in the satellite precipitation is a few hours later (especially for TRMM and PERSIANN) than that in the surface observations over most land and ocean, and it is closer to the phase of showery precipitation from the weather reports. The TRMM and PERSIANN precipitation shows a spatially coherent time of maximum around 0300–0600 local solar time (LST) for a weak (amplitude <20%) semi-diurnal (12-h) cycle over most mid- to high-latitudes, comparable to 0400–0600 LST in the surface data. The satellite data also confirm the notion that the diurnal cycle of precipitation amount comes mostly from its frequency rather than its intensity over most low and mid-latitudes, with the intensity has only about half of the strength of the diurnal cycle in the frequency and amount. The results suggest that these relatively new precipitation products can be useful for many applications.

Flagship species on covers of US conservation and nature magazines

Abstract: Some conservation organizations publish magazines that showcase current conservation and research projects, attract new subscribers and maintain membership, often using flagship species to promote these objectives. This study investigates the nature of flagship species featured on the covers of ten representative US conservation and nature magazines, Defenders, National Wildlife, Wildlife Conservation, Zoonooz, Nature Conservancy, Outdoor America, Sierra, Audubon, California Wild and Natural History. Operationally defining flagship species by diet, taxonomic order, body size and IUCN status, we found that magazines tend to use mammal and bird species rather than invertebrate, fish, amphibian, reptile or plant taxa on their covers. Featured birds were mostly omnivorous or piscivorous, large-bodied and of little conservation concern; featured mammals were mainly carnivorous or herbivorous, large-bodied and of considerable conservation concern. These analyses confirm, for the first time, anecdotal observations about conservation organizations focusing their publicity and programmes on large, charismatic species to raise awareness and funds and raise the spectre that the public may be exposed to only a selected sample of conservation problems.

Lectures on the Langlands program and conformal field theory

Abstract: These lecture notes give an overview of recent results in geometric Langlands correspondence which may yield applications to quantum field theory. We start with a motivated introduction to the Langlands Program, including its geometric reformulation, addressed primarily to physicists. I tried to make it as self-contained as possible, requiring very little mathematical background. Next, we describe the connections between the Langlands Program and two-dimensional conformal field theory that have been found in the last few years. These connections give us important insights into the physical implications of the Langlands duality.

Management of Resistance in Arthropods

Abstract: Since the earliest days of their awareness of resistance, entomologists have been concerned with understanding the factors responsible for its development and with divising measures for its control. It is remarkable that in reporting the first case of resistance — in the San Jose scale toward lime sulfur — Melander (1914) recognized the role of incomplete coverage and genetic recessiveness and speculated that should the scale become resistant also to oil sprays “we might have to introduce a weak strain to cross with the immune and thus return to the normal susceptible population.” Melander and other early pioneers in studies of resistance (Quayle 1922, Woglum 1925) may have been ahead of their time, however, for in the subsequent 30 years or so, resistance evolved slowly, affecting only 12 species of arthropods (review by Babers 1949). Interest in resistance intensified with the introduction of DDT and with the rapid development in cases of resistance to organochlorine, organophos-phate, carbamate and most recently to pyrethroid insecticides. The phenomenon now involves at least 428 species of arthropods and every class of commonly available compound (Georghiou and Mellon, this volume).

Remarks on Zero Viscosity Limit for Nonstationary Navier- Stokes Flows with Boundary

Abstract: This paper is concerned with the question of convergence of the nonstationary, incompressible Navier-Stokes flow u = u v to the Euler flow u as the viscosity v tends to zero. If the underlying space domain is all of Rm, the convergence has been proved by several authors under appropriate assumptions on the convergence of the data (initial condition and external force); see Golovkin [1] and McGrath [2] for m = 2 and all time, and Swann [3] and the author [4,5] for m = 3 and short time. The case m ⩾ 4 can be handled in the same way; in fact, the simple method given in [5] applies to any dimension. All these results refer to strong solutions (or even classical solutions, depending on the data) of the Navier-Stokes equation.