The long-distance flight behavior of Drosophila supports an agent-based model for wind-assisted dispersal in insects.

Despite the ecological importance of long-distance dispersal in insects, its mechanistic basis is poorly understood in genetic model species, in which advanced molecular tools are readily available. One critical question is how insects interact with the wind to detect attractive odor plumes and increase their travel distance as they disperse. To gain insight into dispersal, we conducted release-and-recapture experiments in the Mojave Desert using the fruit fly, Drosophila melanogaster We deployed chemically baited traps in a 1 km radius ring around the release site, equipped with cameras that captured the arrival times of flies as they landed. In each experiment, we released between 30,000 and 200,000 flies. By repeating the experiments under a variety of conditions, we were able to quantify the influence of wind on flies' dispersal behavior. Our results confirm that even tiny fruit flies could disperse ∼12 km in a single flight in still air and might travel many times that distance in a moderate wind. The dispersal behavior of the flies is well explained by an agent-based model in which animals maintain a fixed body orientation relative to celestial cues, actively regulate groundspeed along their body axis, and allow the wind to advect them sideways. The model accounts for the observation that flies actively fan out in all directions in still air but are increasingly advected downwind as winds intensify. Our results suggest that dispersing insects may strike a balance between the need to cover large distances while still maintaining the chance of intercepting odor plumes from upwind sources.

Intensive care unit-acquired weakness in the burn population.

Intensive care unit-acquired weakness is an evolving problem in the burn population. As patients are surviving injuries that previously would have been fatal, the focus of treatment is shifting from survival to long-term outcome. The rehabilitation of burn patients can be challenging; however, a certain subgroup of patients have worse outcomes than others. These patients may suffer from intensive care unit-acquired weakness, and their treatment, physiotherapy and expectations need to be adjusted accordingly. This study investigates the condition of intensive care unit-acquired weakness in our burn centre. We conducted a retrospective analysis of all the admissions to our burn centre between 2008 and 2012 and identified 22 patients who suffered from intensive care unit-acquired weakness. These patients were significantly younger with significantly larger burns than those without intensive care unit-acquired weakness. The known risk factors for intensive care unit-acquired weakness are commonplace in the burn population. The recovery of these patients is significantly affected by their weakness.

Albumin resuscitation in burns: a hybrid regime to mitigate fluid creep.

INTRODUCTION: Globally, many burns units moved away from colloid resuscitation in response to the Cochrane review (1998). Recent literature has introduced the concept of fluid creep: patients receiving volumes far in excess of the upper limit of the Parkland formula. The Cochrane review has been widely criticised, however, and we continued to use 4.5% human albumin solution after 8 h of crystalloid as a hybrid of Parkland and Muir & Barclay's regime. METHODS: Adult patients ⩾15% TBSA were identified from data prospectively entered into our database over a 5-year period (2003-2008). Medical notes and intensive care charts were reviewed comparing volumes of fluids received with requirement estimates. Adverse events were also documented. RESULTS: A total of 72 cases with 34 sets of intensive care charts were analysed. Mean TBSA was 35.2% (range, 15-95%). A total of 75% survived; 3% were haemofiltered. Forty-one percent of patients were resuscitated using the Parkland formula alone, while 59% switched at 8 h post burn to the Muir and Barclay formula (Hybrid group). There was a significantly greater TBSA in the Hybrid group, but they received significantly less fluid volumes than the Parkland group (P = 0.0363; the Hybrid group received 1.36 times calculated need vs. 1.62 in the Parkland group). CONCLUSION: Our patients still demonstrate fluid creep, but to a lesser extent than previously reported. Fluid creep has been mitigated but not eliminated through this strategy.

Effects of cyclic loading and toothbrush abrasion on cervical lesion formation.

This study sought to determine the effect of cyclic loading and toothbrush abrasion (with and without abrasive slurries) on cervical lesion formation. The roots of extracted human third molars were embedded in acrylic resin, leaving 2 mm of root structure and crowns exposed. Teeth were divided into 6 groups (n = 10) with the following treatments: no treatment (control), cyclic load in distilled water, brushing with distilled water, cyclic load followed by brushing with distilled water, brushing with toothpaste slurry, and cyclic load followed by brushing with toothpaste slurry. Cyclic loading and toothbrushing machines subjected the teeth to 1.6 million cyclic loads and 30,000 brushing strokes, the equivalent of 4 years of function and brushing for an average patient. The teeth were scanned with a 3-dimensional optical profilometer to determine the volumetric loss of tooth structure. Load cycling had no significant effect on cervical tooth loss. Brushing with toothpaste resulted in significantly greater cervical tooth loss than brushing with water, which in turn was significantly greater than no treatment at all.

Hovering flight in the honeybee Apis mellifera: kinematic mechanisms for varying aerodynamic forces.

During hovering flight, animals can increase the wing velocity and therefore the net aerodynamic force per stroke by increasing wingbeat frequency, wing stroke amplitude, or both. The magnitude and orientation of aerodynamic forces are also influenced by the geometric angle of attack, timing of wing rotation, wing contact, and pattern of deviation from the primary stroke plane. Most of the kinematic data available for flying animals are average values for wing stroke amplitude and wingbeat frequency because these features are relatively easy to measure, but it is frequently suggested that the more subtle and difficult-to-measure features of wing kinematics can explain variation in force production for different flight behaviors. Here, we test this hypothesis with multicamera high-speed recording and digitization of wing kinematics of honeybees (Apis mellifera) hovering and ascending in air and hovering in a hypodense gas (heliox: 21% O2, 79% He). Bees employed low stroke amplitudes (86.7° ± 7.9°) and high wingbeat frequencies (226.8 ± 12.8 Hz) when hovering in air. When ascending in air or hovering in heliox, bees increased stroke amplitude by 30%-45%, which yielded a much higher wing tip velocity relative to that during simple hovering in air. Across the three flight conditions, there were no statistical differences in the amplitude of wing stroke deviation, minimum and stroke-averaged geometric angle of attack, maximum wing rotation velocity, or even wingbeat frequency. We employed a quasi-steady aerodynamic model to estimate the effects of wing tip velocity and geometric angle of attack on lift and drag. Lift forces were sensitive to variation in wing tip velocity, whereas drag was sensitive to both variation in wing tip velocity and angle of attack. Bees utilized kinematic patterns that did not maximize lift production but rather maintained lift-to-drag ratio. Thus, our data indicate that, at least for honeybees, the overall time course of wing angles is generally preserved and modulation of wing tip velocity is sufficient to perform a diverse set of vertical flight behaviors.

Gram negative wound infection in hospitalised adult burn patients--systematic review and metanalysis-.

BACKGROUND: Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres. METHODS: Studies investigating adult hospitalised patients (2000-2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance. PRIMARY FINDINGS: Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens' incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84). INTERPRETATION: Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative "target organisms" facilitate clinical practice and target research towards a defined clinical demand.

A cost-effective and simple electronic solution to communication with patients with tracheostomy in a burns and intensive care setting.

INTRODUCTION AND AIMS: Ventilated patients in ITU (intensive treatment unit) tend to be challenging to communicate with, especially patients who are being weaned. These patients usually have tracheostomy in situ and use means such as writing or letter boards to communicate. The situation becomes complex in patient groups that have burn injuries with bulky dressings and restricted upper limb function. We demonstrate a low cost, easy to use, potentially disposable system that can display words on any television screen via patient input device for such patient groups. MATERIALS AND METHODS: The system consists of input device incorporated with Arduino microcontroller (an open-source electronics prototyping platform based on easy-to-use hardware and software intended for creating interactive environments) and 4 generously oversized control buttons. These are used to control the cursor movements (up, down, left, right) while a fifth has a "select" function. These are large enough to be pressed by an entire bandaged hand using gross upper limb movements only. A standard television is used to display menu containing the 26 letters of the alphabet and a flashing cursor. The patient selects the required letters/icon by moving the cursor and the words so created are displayed along the lower part of the screen for the carers to read. It is envisaged that anyone with basic craft skills should be able to construct this device. CONCLUSION: This device is a self-contained, cost-effective, simple, and open-source system that can be used effectively to bridge the communication gap with significant potential for patient care globally.

Colistin in burn intensive care: back to the future?

Colistin is a venerable antibiotic whose fortunes have been revived by its excellent activity, the diminishing output of novel clinically effective antibiotics and the increasing importance of MDR infection in burn surgery, both in the civilian and military arenas. This review synthesizes current evidence on the usage of colistin in burn surgery including the structure-activity relationship; dosing, pharmacokinetics/pharmacodynamic (PK/PD), analytic methods, resistance and current research efforts into the redevelopment of this antibiotic, to distil recommendations for future research and clinical efficacy.

Application of topical negative pressure (vacuum-assisted closure) to split-thickness skin grafts: a structured evidence-based review.

INTRODUCTION: Significant controversy surrounds the effectiveness of negative pressure wound therapy although it has been in use for decades. Although many clinicians favor this modality in relation to its practicality, ease of use especially in complex wounds, it has faced the same challenges as other dressings in relation to evidence base of efficacy in relation to a number of outcome measures. In view of the current financial pressures on health care systems worldwide, this structured review systematically challenges the evidence for perioperative application of topical negative pressure (TNP) to split-thickness skin grafts (STSGs) through evidence-based critical appraisal, and extrapolate the mechanisms of action on the mechanisms through which TNP may aid wound healing. Weighted evidence-based recommendations regarding the impact of TNP on split skin graft quality and quantity of take as outcomes. METHODS: Phase 1: Structured literature search. Phase 2: Retrieved articles were critically appraised for rigor and methodological validity by 3 independent authors, then stratified according to a validated "levels of evidence" framework. Graded "current best evidence" recommendations could therefore be proposed. RESULTS: Of the 220 studies retrieved in the initial search, 38 studies satisfied our quality of evidence criteria. Current best evidence supports 2 complementary trends explaining the mechanisms whereby STSG benefits from TNP. Active stimulation of epithelial mitosis: TNP creates mechanical stretch which stimulates multiple signaling pathways up-regulating growth- and mitosis-associated epithelial transcription factors. Topical negative pressure also promotes microcirculatory flow (graft and wound edge), stimulates angiogenesis and basement membrane integrity (grade C). Prevention of complications: significant reduction of graft lift-off by edema, exudates, subgraft hematoma, and reduction of shear when compared to traditional dressings (grade B). Topical negative pressure promotes significant qualitative improvement in the final STSG result studies (level 1B). The role of TNP in prevention of infection is, however, equivocal and further research is required. No evidence of harm from TNP application was reported. CONCLUSIONS: Topical negative pressure increases quantity and quality of split skin graft take compared to traditional bolster dressings. The advantages are increased in irregularly contoured, technically difficult wounds and suboptimal recipient wound beds where it seems to be the best modality currently available. Large-scale randomized clinical controlled trials remain scanty in all areas of wound dressing research including negative pressure therapy.

Association between sitagliptin adherence and self-monitoring of blood glucose.

BACKGROUND: We evaluated the association between self-monitoring of blood glucose (SMBG) use and sitagliptin or sitagliptin/metformin (SSMT) adherence. SSMT was chosen as these medications have little risk of hypoglycemia and are believed to not require SMBG data for titration. METHODS: This was an observational study using data extracted from a large United States insurance claims database (i3 InVision™ Data Mart, Ingenix, Inc.). Data were extracted on noninsulin-using patients initiating SSMT for each 12-month period pre- and post-SSMT initiation. Logistic regression was used to assess the relationship between SMBG use and the likelihood of being medication adherent (defined as a medication possession ratio of ≥75%) while controlling for covariates. RESULTS: This analysis included 7,306 patients (57.6% male; mean age 54.2 years). Mean pre-SSMT hemoglobin A1c (HbA1c) was 8.0%. In the post-SSMT initiation period, 58% of patients were adherent with SSMT. Older age, male gender, prior use of oral diabetes medication, and lower HbA1c were associated with improved SSMT adherence. SMBG use was associated with improved adherence [odds ratio (OR) ranged from 1.198 to 1.338; p < .05] compared with patients with no SMBG use pre- or post-SSMT initiation. For patients who began SMBG after starting SSMT, greater SMBG use was associated with better adherence (OR 1.449 for higher vs 1.246 for lower strip use; p < .05). CONCLUSIONS: This study demonstrated that SMBG is associated with improved SSMT adherence. This relationship is strengthened with greater SMBG use.

The influence of sensory delay on the yaw dynamics of a flapping insect.

In closed-loop systems, sensor feedback delays may have disastrous implications for performance and stability. Flies have evolved multiple specializations to reduce this latency, but the fastest feedback during flight involves a delay that is still significant on the timescale of body dynamics. We explored the effect of sensor delay on flight stability and performance for yaw turns using a dynamically scaled robotic model of the fruitfly, Drosophila. The robot was equipped with a real-time feedback system that performed active turns in response to measured torque about the functional yaw axis. We performed system response experiments for a proportional controller in yaw velocity for a range of feedback delays, similar in dimensionless timescale to those experienced by a fly. The results show a fundamental trade-off between sensor delay and permissible feedback gain, and suggest that fast mechanosensory feedback in flies, and most probably in other insects, provide a source of active damping which compliments that contributed by passive effects. Presented in the context of these findings, a control architecture whereby a haltere-mediated inner-loop proportional controller provides damping for slower visually mediated feedback is consistent with tethered-flight measurements, free-flight observations and engineering design principles.

Emerging gram-negative infections in burn wounds.

Gram-negative infection remains a major contributor to morbidity, mortality, and cost of care. In the absence of comparative multinational epidemiological studies specific to burn patients, we sought to review literature trends in emerging Gram-negative burn wound infections within the past 60 years. Mapping trends in these organisms, although in a minority compared with the six "ESKAPE" pathogens currently being targeted by the Infectious Diseases Society of North America, would identify pathogens of increasing concern to burn physicians in the near future and develop patient profiles that may predict susceptibility to infection. Aeromonas hydrophila infection was identified as the emerging pathogen of note, constituting 76% of the identified publications. A. hydrophila constituted 96% of Aeromonas spp. isolates (mortality 10.7%). The following patient profile indicated predisposition to Aeromonas infection: mean age (mean 33.7 years, range 17 ≤ R ≤ 80, SD = 15.6); TBSA (mean 41.1%, range 8% ≤ R ≤ 80%, SD = 15.2); full-thickness skin burns (mean 27.7%, range 3% ≤ R ≤ 60%, SD = 16.6); and a male predominance (81.3%). Other pathogens included Stenotrophomonas maltophilia Vibrio spp., Chryseobacterium spp., Alcaligenes xylosoxidans, and Cedecia lapigei. Arresting the thermal injury by untreated water was the common predisposing factor. These emerging infections clearly constitute a minority of Gram-negative bacterial infections in burn patients at present. However, these are the infections most likely to pose significant clinical challenge because of the high prevalence of multidrug resistance, rapid acquisition of multidrug resistance, high mortality, and ubiquity in the natural environment. This article therefore presents a rationale for understanding and recognizing the role of these emerging infections in burn patients.

Prior mating experience modulates the dispersal of Drosophila in males more than in females.

Cues from both an animal's internal physiological state and its local environment may influence its decision to disperse. However, identifying and quantifying the causative factors underlying the initiation of dispersal is difficult in uncontrolled natural settings. In this study, we automatically monitored the movement of fruit flies and examined the influence of food availability, sex, and reproductive status on their dispersal between laboratory environments. In general, flies with mating experience behave as if they are hungrier than virgin flies, leaving at a greater rate when food is unavailable and staying longer when it is available. Males dispersed at a higher rate and were more active than females when food was unavailable, but tended to stay longer in environments containing food than did females. We found no significant relationship between weight and activity, suggesting the behavioral differences between males and females are caused by an intrinsic factor relating to the sex of a fly and not simply its body size. Finally, we observed a significant difference between the dispersal of the natural isolate used throughout this study and the widely-used laboratory strain, Canton-S, and show that the difference cannot be explained by allelic differences in the foraging gene.

A linear systems analysis of the yaw dynamics of a dynamically scaled insect model.

Recent studies suggest that fruit flies use subtle changes to their wing motion to actively generate forces during aerial maneuvers. In addition, it has been estimated that the passive rotational damping caused by the flapping wings of an insect is around two orders of magnitude greater than that for the body alone. At present, however, the relationships between the active regulation of wing kinematics, passive damping produced by the flapping wings and the overall trajectory of the animal are still poorly understood. In this study, we use a dynamically scaled robotic model equipped with a torque feedback mechanism to study the dynamics of yaw turns in the fruit fly Drosophila melanogaster. Four plausible mechanisms for the active generation of yaw torque are examined. The mechanisms deform the wing kinematics of hovering in order to introduce asymmetry that results in the active production of yaw torque by the flapping wings. The results demonstrate that the stroke-averaged yaw torque is well approximated by a model that is linear with respect to both the yaw velocity and the magnitude of the kinematic deformations. Dynamic measurements, in which the yaw torque produced by the flapping wings was used in real-time to determine the rotation of the robot, suggest that a first-order linear model with stroke-average coefficients accurately captures the yaw dynamics of the system. Finally, an analysis of the stroke-average dynamics suggests that both damping and inertia will be important factors during rapid body saccades of a fruit fly.

Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna).

Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate - a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle(-1)). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies.

The use of the Flexi-Seal Faecal Management System in laparostomy wounds involving enterocutaneous fistula.

We present an innovative application of the Flexi-Seal Faecal Management System (FMS) for the diversion of upper and lower gastrointestinal secretions from enterocutaneous fistulae associated with complex wounds. Fistula is a common complication after the formation of a laparostomy, secondary to cases of severe intra-abdominal sepsis, acute mesenteric ischaemia, necrotising infection of the abdominal wall, or intra-abdominal hypertension. A significant mortality rate is associated with such fistula. With the successful continent diversion of gastrointestinal secretions by the Flexi-Seal FMS, abdominal wounds can be successfully skin-grafted, and wound healing expedited.