Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming.

Aggregation can reduce an individual's predation risk, by decreasing predator hunting efficiency or displacing predation onto others. Here, we explore how the behaviors of predator and prey influence catch success and predation risk in Swainson's hawks Buteo swainsoni attacking swarming Brazilian free-tailed bats Tadarida brasiliensis on emergence. Lone bats including stragglers have a high relative risk of predation, representing ~5% of the catch but ~0.2% of the population. Attacks on the column were no less successful than attacks on lone bats, so hunting efficiency is not decreased by group vigilance or confusion. Instead, lone bats were attacked disproportionately often, representing ~10% of all attacks. Swarming therefore displaces the burden of predation onto bats outside the column-whether as isolated wanderers not benefitting from dilution through attack abatement, or as peripheral stragglers suffering marginal predation and possible selfish herd effects. In contrast, the hawks' catch success depended only on the attack maneuvers that they employed, with the odds of success being more than trebled in attacks involving a high-speed stoop or rolling grab. Most attacks involved one of these two maneuvers, which therefore represent alternative rather than complementary tactics. Hence, whereas a bat's survival depends on maintaining column formation, a hawk's success does not depend on attacking lone bats-even though their tendency to do so is sufficient to explain the adaptive benefits of their prey's aggregation behavior. A hawk's success instead depends on the flight maneuvers it deploys, including the high-speed stoop that is characteristic of many raptors. Swarming bats emerging from a massive desert roost reduce their predation risk by maintaining tight column formation, because the hawks that predate them attack peripheral stragglers and isolated wanderers disproportionately. Whereas a bat's predation risk depends on maintaining its position within the column, the catch success of a hawk depends on how it maneuvers itself to attack, and is maximized by executing a high-speed dive or rolling grab maneuver.

Improving hyperglycemia management in the intensive care unit: preliminary report of a nurse-driven quality improvement project using a redesigned insulin infusion algorithm.

PURPOSE: The purpose of this study was to assess the feasibility of a nurse-driven effort to improve hyperglycemia management in the intensive care unit (ICU) setting. METHODS: The setting was the ICU of a large urban hospital. The program was composed of 3 components: nurses as leaders, a clinical pathway to identify patients in need of hyperglycemia therapy, and implementation of a redesigned insulin infusion algorithm (the Columnar Insulin Dosing Chart). Time to reach a target glucose range of 80 to 110 mg/dL (4.4-6.1 mmol/L) was evaluated. RESULTS: One hundred sixteen ICU nurses were trained in the project. The Columnar Insulin Dosing Chart was applied to 20 patients. The average time required to reach the target blood glucose range was 12.8 hours. Below-target blood glucose levels were 6.9% of all blood glucose levels recorded, but only 0.9% were below 60 mg/dL (3.3 mmol/L). There was no sustained hypoglycemia, and no persistent clinical findings attributable to hypoglycemia were noted. Barriers to implementing the project included an increased nursing workload, the need for more finger-stick blood glucose monitors, and the need to acquire new finger-lancing devices that allowed for shallower skin puncture and increased patient comfort. CONCLUSIONS: Tighter glycemic control goals can be attained in a busy ICU by a nurse-led team using a pathway for identifying and treating hyperglycemia, clear decision support tools, and adequate nurse education. The novel chart-based insulin infusion algorithm chosen as the standard for this pilot was an effective tool for reducing the blood glucose to target range with no clinically significant hypoglycemia.

Working to improve care of hospital hyperglycemia through statewide collaboration: the Georgia Hospital Association Diabetes Special Interest Group.

OBJECTIVE: To review the efforts of the Georgia Hospital Association Diabetes Special Interest Group (DSIG) to develop and disseminate sample clinical guidelines on management of inpatient hyperglycemia. METHODS: Beginning in February 2003, a consortium of physicians and allied health professionals from throughout the state of Georgia began meeting on a frequent basis to formulate a plan to enhance the care of hospitalized patients with hyperglycemia. The immediate goals of the DSIG were the identification and organization of interested stakeholders, the development of consensus sample clinical guidelines, and the dissemination of information. RESULTS: Since its inception, the DSIG has accomplished the following: development of 7 consensus sample clinical guidelines, construction of a Web site that posts these clinical guidelines and other useful related information and educational materials, and sponsorship of workshops throughout the state of Georgia. CONCLUSION: As the importance of glucose control in the hospital setting has become increasingly recognized, institutions must find ways of applying results of clinical trials to "real-world" hospital environments. The DSIG is an example of a successful collaboration that could serve as a model for other state hospital organizations that wish to develop programs to enhance the care of inpatients with hyperglycemia.