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.

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

Abstract: The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels.

Drug enhancement of memory consolidation: historical perspective and neurobiological implications

Abstract: Introduction Studies of drug enhancement of cognition began with Lashley’s (Psychobiology 1:141–170, 1917) report that strychnine administered before daily training trials enhanced rats’ maze learning. Many subsequent studies confirmed that finding and found that stimulant drugs also enhance the learning of a wide range of tasks.

Extensive Rearrangements in the Chloroplast Genome of Trachelium caeruleum Are Associated with Repeats and tRNA Genes

Abstract: Chloroplast genome organization, gene order, and content are highly conserved among land plants. We sequenced the chloroplast genome of Trachelium caeruleum L. (Campanulaceae), a member of an angiosperm family known for highly rearranged genomes. The total genome size is 162,321 bp, with an inverted repeat (IR) of 27,273 bp, large single-copy (LSC) region of 100,114 bp, and small single-copy (SSC) region of 7,661 bp. The genome encodes 112 different genes, with 17 duplicated in the IR, a tRNA gene (trnI-cau) duplicated once in the LSC region, and a protein-coding gene (psbJ) with two duplicate copies, for a total of 132 putatively intact genes. ndhK may be a pseudogene with internal stop codons, and clpP, ycf1, and ycf2 are so highly diverged that they also may be pseudogenes. ycf15, rpl23, infA, and accD are truncated and likely nonfunctional. The most conspicuous feature of the Trachelium genome is the presence of 18 internally unrearranged blocks of genes inverted or relocated within the genome relative to the ancestral gene order of angiosperm chloroplast genomes. Recombination between repeats or tRNA genes has been suggested as a mechanism of chloroplast genome rearrangements. The Trachelium chloroplast genome shares with Pelargonium and Jasminum both a higher number of repeats and larger repeated sequences in comparison to eight other angiosperm chloroplast genomes, and these are concentrated near rearrangement endpoints. Genes for tRNAs occur at many but not all inversion endpoints, so some combination of repeats and tRNA genes may have mediated these rearrangements.

Hybrid universal broadband telecommunications using small radio cells interconnected by free-space optical links

Abstract: Diverse communication terminals attach via broadband radio to a communications network at any of typically three hierarchical cell sizes; picocells (1), standard cells (2) and macro cells (3), increasing from, typically, a single building to a city to a region. Almost all telecommunications traffic transpires, however, within the lowest levele picocells (1) to and from low cost base stations (11) that have typically one radio transceiver (111), four optical transceivers (112) an ATM switch (11) and an ATM controller (114). Each local base station (11) is interconnected to a regional end office switch (12), where a connection to a worldwide wire/fiber line communications backbone (4), upon a multi-hop mesh network (100) via short highly-focused free-space broadband directional optical links (10). By this free-space wireless broadband access, subscriber service requirements on the order of 20 Mbps peak rate and 10 Mbps average are provided.

Naloxone distribution and cardiopulmonary resuscitation training for injection drug users to prevent heroin overdose death: A pilot intervention study

Abstract: Fatal heroin overdose has become a leading cause of death among injection drug users (IDUs). Several recent feasibility studies have concluded that naloxone distribution programs for heroin injectors should be implemented to decrease heroin overdose deaths, but there have been no prospective trials of such programs in North America. This pilot study was undertaken to investigate the safety and feasibility of training injection drug using partners to perform cardiopulmonary resuscitation (CPR) and administer naloxone in the event of heroin overdose. During May and June 2001, 24 IDUs (12 pairs of injection partners) were recruited from street settings in San Francisco. Participants took part in 8-hour training in heroin overdose prevention, CPR, and the use of naloxone. Following the intervention, participants were prospectively followed for 6 months to determine the number and outcomes of witnessed heroin overdoses, outcomes of participant interventions, and changes in participants’ knowledge of overdose and drug use behavior. Study participants witnessed 20 heroin overdose events during 6 months follow-up. They performed CPR in 16 (80%) events, administered naloxone in 15 (75%) and did one or the other in 19 (95%). All overdose victims survived. Knowledge about heroin overdose management increased, whereas heroin use decreased. IDUs can be trained to respond to heroin overdose emergencies by performing CPR and administering naloxone. Future research is needed to evaluate the effectiveness of this peer intervention to prevent fatal heroin overdose.