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.

Mapping wetland changes in China between 1978 and 2008

Abstract: Four wetland maps for all China have been produced, based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978, 1990, 2000 and 2008). These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009. Based on these maps, we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years. (i) There were about 324097 km(2) of wetlands in 2008, for which inland marshes or swamps were the most common wetland type (35%), with lakes (26%) second. Most of the wetlands were in Heilongjiang, Inner Mongolia, Qinghai and Tibet, occupying about 55% of the national wetland area. (ii) From 1978 to 2008, China's wetland area continually and significantly decreased, by about 33% based on changes in the wetland map. This was in sharp contrast to the increase in artificial wetlands, which increased by about 122%. Inland marshes accounted for the main loss of total wetlands from 1978 to 2000. From 2000 through 2008, riverine and lacustrine wetlands constituted the main wetland loss. Fortunately however, the rate of wetland loss decreased from 5523 to 831 km(2)/a. (iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years. From 1978 to 1990, nearly all natural wetlands (98%) lost were transformed into non-wetlands. However, the ratio declined to 86% from 1990 to 2000, and to 77% from 2000 to 2008. (iv) All Chinese provinces were divided into three groups according to patterns of wetland changes, which could relate to the driving forces of such changes. Tibet was completely different from other provinces, as it was one representative example in which there was a net wetland increase, because of global warming and decreased human activity since 1990. Increased economic development caused considerable wetland loss in most eastern provinces, and artificial wetlands increased.

Strategic Pricing of New Pharmaceuticals

Abstract: This paper provides empirical evidence on the leading factors affecting the prices of new pharmaceuticals, both at introduction and after 4, 6, and 8 years. Most important is the extent of therapeutic advance embodied in a new product. For drugs which represent important therapeutic gains, launch prices can be two or three times those of existing drugs used for the same purposes, while drugs that largely duplicate the actions of currently available products are typically priced at comparable levels. In addition, the number of branded substitutes has a substantial negative effect on launch prices, which reflects the importance of competitive pressures. Duplicate products thereby play an important economic role in pharmaceutical markets.

What antimicrobial resistance has taught us about horizontal gene transfer.

Abstract: Horizontal gene transfer (HGT) has been responsible for the dissemination of numerous antimicrobial-resistance determinants throughout diverse bacterial species. The rapid and broad dissemination of resistance determinants by HGT, and subsequent selection for resistance imposed by the use of antimicrobials, threatens to undermine the usefulness of antimicrobials. However, vigilant surveillance of the emerging antimicrobial resistance in clinical settings and subsequent studies of resistant isolates create a powerful system for studying HGT and detecting rare events. Two of the most closely monitored phenotypes are resistance to beta-lactams and resistance to fluoroquinolones. Studies of resistance to these antimicrobials have revealed that (1) transformation occurs between different species of bacteria including some recipient species that were not previously known to be competent for natural transformation; (2) transduction may be playing an important role in generating novel methicillin-resistant Staphylococcus aureus (MRSA) strains, although the details of transferring the SCCmec element are not yet fully understood; (3) Resistance genes are probably moving to plasmids from chromosomes more rapidly than in the past; and (4) Resistance genes are aggregating upon plasmids. The linkage of numerous resistance genes on individual plasmids may underlie the persistence of resistance to specific antimicrobials even when use of those antimicrobials is discontinued. Further studies of HGT and methods for controlling HGT may be necessary to maintain the usefulness of antimicrobials.

Dependability and Its Threats: A Taxonomy

Abstract: This paper gives the main definitions relating to dependability, a generic concept including as special case such attributes as reliability, availability, safety, confidentiality, integrity, maintainability, etc. Basic definitions are given first. They are then commented upon, and supplemented by additional definitions, which address the threats to dependability (faults, errors, failures), and the attributes of dependability. The discussion on the attributes encompasses the relationship of dependability with security, survivability and trustworthiness.

Descriptive statistics for nonparametric models iv. spread

Abstract: Ordering by spread. In the preceding paper of this series [1] (to which we refer as BL III) we studied the dispersion of a symmetric distribution about its center of symmetry. In the present paper we study a related aspect of dispersion, which does not require the assumption of symmetry but which even in the symmetric case does not coincide with the concept considered in BL III. Roughly speaking, instead of looking at dispersion relative to a fixed point, we now consider the spread of a random variable throughout its distribution. The difference is perhaps best explained in terms of an example.