Search

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colonys primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ants lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host-microbe symbioses.

Multiprocessors provide a cost effective high performance alternative for relational join execution. While traditional query processing algorithms can be effectively utilized to realize interquery parallelism, they are not well suited to exploiting intraquery parallelism. In this paper we present a practical join processing strategy which allows effective utilization of arbitrary degrees of parallelism in both the I/O subsystem and join processing (processor) subsystems. Analytic bounds on the minimum execution time, minimum number of processors, and processor utilization are presented along with bounds on the execution time given a fixed number of processors. These bounds assume sufficient buffers are available. We present an analytic lower bound on buffer requirements as well as a practical heuristic for use in limited buffer environments. The paper concludes with a sampling of corroborative simulation results.

The article focuses on how the U.S. Army Nurse Corps (ANS) implements shared governance through the creation of unit practice council (UPC) in the primary care department. Topics include the importance of shared governance in improving job satisfaction and retention of nurses in military facilities, the development of the professional practice model called the Patient Caring Touch System (PCTC) by ANC in 2010, and the support of senior nurse leaders in forming UPCs.

Postoperative nausea and vomiting (PONV) continue to be among the most undesirable and distressing complications following general anesthesia, affecting 20% to 30% of all surgical patients and up to 70% of patients with multiple known risk factors. The purpose of this study was to reexamine the effectiveness of metoclopramide in the prevention of PONV when stratified by PONV risk scores. Secondary data from 2,116 adult ambulatory surgical patients were analyzed. Participants were, on average (SD), 49.7 (15.4) years of age, with a mean body mass index of 28.3 (6.9) kg/m², and were primarily female (65%). Risk scores for PONV ranged from 0 to 4, with a mean of 2.6 (1.0). Metoclopramide, 10 mg intravenously (IV) alone; metoclopramide, 10 mg IV, combined with ondansetron, 4 mg IV; and metoclopramide, 10 mg IV, combined with dexamethasone, 8 mg IV, and ondansetron, 4 mg IV, had a beneficial effect for adult ambulatory surgical patients with PONV risk scores of 1 to 4. Although this cohort study had limitations, future studies should investigate metoclopramide based on risk score recommendations, and guidelines should be reevaluated., Competing Interests: The authors have declared no financial relationships with any commercial entity related to the content of this article. The authors did not discuss off-label use within the article., (Copyright© by the American Association of Nurse Anesthetists.)