固体物理学VS粒子物理学通往科学的真理

在科学的伟大梯队中，粒子物理学家把自己和天使放在了一起。他们从天堂向下俯视着化学家、生物学家、地质学家以及气象学家等这些应用而不是发现自然界最基本规律的人。甚至属于同一学科的固体物理学也常常被认为是在进行次要的研究。夸克的发现者默里·盖尔曼把它称为“肮脏态物理学”，其他一些人也对这个“没有价值的物理学”大加排斥。近年来，这些所谓“垃圾学科”发展神速。在一场科学文化的较量中，一些卓越的固体物理学家已经对粒子物理学家作为“终极真理的仲裁者”地位发起了挑战。因在固体物理学中的几项发现而获得1998年度诺贝…     

Small-stone content of Mima mounds of the Columbia Plateau and Rocky Mountain regions: implications for mound origin

Mima moundfields were investigated at the Lawrence Memorial Grassland Preserve, located on the Columbia Plateau in southern Wasco County, Oregon, and at three locations in the San Luis Valley and Sangre de Cristo Mountains, southern Colorado, to test the alternative hypotheses of mound origins by erosion, frost action, and soil translocation by geomyid pocket gophers. The concentrations of two size classes of small stones, gravel (8-15 mm diameter) and pebbles (15-50 mm diameter), were sampled along mound-to-intermound transects and at different depths within the mounds. Numbers and masses of small stones per unit soil volume increased from intermounds to mounds tops at the Colorado sites and from mound edge to mound top at the Oregon site, where thin intermound soils lay directly on the weathering surface of basalt bedrock. Numbers and masses of small stones in the surface soil of mound tops were greater than or similar to concentrations in deeper layers. Mean masses of individual pebbles were greater in the intermound zone than in mound soils at the Oregon site, but did not differ along mound-intermound gradient at the Oregon site and at one Colorado site, being highest at mound edges or in intermounds. These observations support the hypothesis that mounds are formed by centripetal translocation of soil by geomyid pocket gophers, and are contrary to predictions based on theories assuming erosion or frost action to be the mechanism of mound formation.     

Recent progress in lanthanide-catalyzed organic reactions in protic media

Lanthanide triflates are stable in water. It is possible for lanthanides to undergo many organic reactions in environmentally friendly solvents. This makes lanthanides very promising in the field of green chemistry. This review describes the recent development of the lanthanidecatalyzed organic reactions in protic solvents. Those reactions include Diels-Alder, Aldol, Allylation, acetalization, pericyclization, radical reactions as well as some newlydeveloped lanthnidesbased catalysts.     

REGULARITY AND RECURRENCE OF SWITCHING DIFFUSIONS

This work is concerned with switching diffusion processes, also known as regime-switching diffusions. Our attention focuses on regularity, recurrence, and positive recurrence of the underlying stochastic processes. The main effort is devoted to obtaining easily verifiable conditions for the aforementioned properties. Continuous-state-dependent jump processes are considered. First general criteria on regularity and recurrence using Liapunov functions are obtained. Then we focus on a class of problems, in which both the drift and the diffusion coefficients are ＂linearizable＂ with respect to the continuous state, and suppose that the generator of the jump part of the process can be approximated by a generator of an ergodic Markov chain. Sufficient conditions for regularity, recurrence, and positive recurrence are derived, which are linear combination of the averaged coefficients （averaged with respect to the stationary measure of the Markov chain）.     

Genetically effective and adult population sizes in the Apache silverspot butterfly, Speyeria nokomis apacheana (Lepidoptera: Mynphalidae)

Genetically effective and adult population sizes of the Apache silverspot butterfly ( Speyeria nokomiis apacheana ) from the Great Basin of North America were tracked from 1991 to 1997. Speyeria nokomis inhabits mesic habitats in the Great Basin, and its recent declines in abundance have raised concerns about its future persistence. Adult population size estimates determined from mark-recapture methods ranged from 100 to 1900 individuals from 1993 through 1997. Genetically effective population sizes based on temporal changes in allozyme frequencies ranged from less tha 1 individual to 20 individuals between 1991 and 1995. Despite these small annual estimates, it is likely that gene flow resulted in overestimation of genetically effective population sizes. These reusuts, combined with observations in the field, suggest that suitable but vacan habitat patches be maintained for potential recolonization by S. n. apacheana.     

Roosting behavior of male Euderma maculatum from Utah

Eight spotted bats ( Euderma maculatum ) were captured and released along the Fort Pierce Wash, Washington County, Utah, in August 1974. Observations indicated that Euderma roosts in cracks and crevices.