Showing papers by "United States Department of the Army published in 2005"

Virtual reality simulation for the operating room: proficiency-based training as a paradigm shift in surgical skills training.

Abstract: Summary Background Data: To inform surgeons about the practical issues to be considered for successful integration of virtual reality simulation into a surgical training program. The learning and practice of minimally invasive surgery (MIS) makes unique demands on surgical training programs. A decade ago Satava proposed virtual reality (VR) surgical simulation as a solution for this problem. Only recently have robust scientific studies supported that vision

An Update on the Potential of North American Mosquitoes (Diptera: Culicidae) to Transmit West Nile Virus

Abstract: Since first discovered in the New York City area in 1999, West Nile virus (WNV) has become established over much of the continental United States and has been responsible for >10,000 cases of severe disease and 400 human fatalities, as well as thousands of fatal infections in horses. To develop appropriate surveillance and control strategies, the identification of which mosquito species are competent vectors and how various factors influence their ability to transmit this virus must be determined. Therefore, we evaluated numerous mosquito species for their ability to transmit WNV under laboratory conditions. This report contains data for several mosquito species not reported previously, as well as a summary of transmission data compiled from previously reported studies. Mosquitoes were allowed to feed on chickens infected with WNV isolated from a crow that died during the 1999 outbreak in New York City. These mosquitoes were tested approximately 2 wk later to determine infection, dissemination, and transmission rates. All Culex species tested were competent vectors in the laboratory and varied from highly efficient vectors (e.g., Culex tarsalis Coquillett) to moderately efficient ones (e.g., Culex nigripalpus Theobald). Nearly all of the Culex species tested could serve as efficient enzootic or amplifying vectors for WNV. Several container-breeding Aedes and Ochlerotatus species were highly efficient vectors under laboratory conditions, but because of their feeding preferences, would probably not be involved in the maintenance of WNV in nature. However, they would be potential bridge vectors between the avian-Culex cycle and mammalian hosts. In contrast, most of the surface pool-breeding Aedes and Ochlerotatus species tested were relatively inefficient vectors under laboratory conditions and would probably not play a significant role in transmitting WNV in nature. In determining the potential for a mosquito species to become involved in transmitting WNV, it is necessary to consider not only its laboratory vector competence but also its abundance, host-feeding preference, involvement with other viruses with similar transmission cycles, and whether WNV has been isolated from this species under natural conditions.

The factor structure of the presence questionnaire

Abstract: Constructing a valid measure of presence and discovering the factors that contribute to presence have been much sought after goals of presence researchers and at times have generated controversy among them. This paper describes the results of principal-components analyses of Presence Questionnaire (PQ) data from 325 participants following exposure to immersive virtual environments. The analyses suggest that a 4-factor model provides the best fit to our data. The factors are Involvement, Adaptation/Immersion, Sensory Fidelity, and Interface Quality. Except for the Adaptation/Immersion factor, these factors corresponded to those identified in a cluster analysis of data from an earlier version of the questionnaire. The existence of an Adaptation/Immersion factor leads us to postulate that immersion is greater for those individuals who rapidly and easily adapt to the virtual environment. The magnitudes of the correlations among the factors indicate moderately strong relationships among the 4 factors. Within these relationships, Sensory Fidelity items seem to be more closely related to Involvement, whereas Interface Quality items appear to be more closely related to Adaptation/Immersion, even though there is a moderately strong relationship between the Involvement and Adaptation/Immersion factors.

Scaling the quality of teammates' mental models: equifinality and normative comparisons

Abstract: We tested the impact of teammates' team and task mental model sharedness on team processes and performance using 70 undergraduate teams that completed a series of missions on a PC-based flight simulator. Moreover, we considered how the quality of mental models might moderate such relationships. Team processes were found to partially mediate the relationship between task mental model sharedness and team performance. Although team mental model sharedness failed to exhibit a significant linear relationship with team processes or performance, it did evidence a multiplicative relationship as moderated by the quality of those models. Team processes and performance were better among teams sharing higher-quality team mental models than among teams evidencing less sharedness or who had lower-quality models. Again, team processes partially mediated these relationships. Results are discussed in terms of the equifinality of mental model quality and applications to various team environments. Copyright © 2005 John Wiley & Sons, Ltd.

The epidemiology and modern management of traumatic hemorrhage: US and international perspectives

Abstract: Trauma is a worldwide problem, with severe and wide ranging consequences for individuals and society as a whole. Hemorrhage is a major contributor to the dilemma of traumatic injury and its care. In this article we describe the international epidemiology of traumatic injury, its causes and its consequences, and closely examine the role played by hemorrhage in producing traumatic morbidity and mortality. Emphasis is placed on defining situations in which traditional methods of hemorrhage control often fail. We then outline and discuss modern principles in the management of traumatic hemorrhage and explore developing changes in these areas. We conclude with a discussion of outcome measures for the injured patient within the context of the epidemiology of traumatic injury.

Conceptual Framework and Statistical Procedures for Delineating and Testing Multilevel Theories of Homology

Abstract: Scholars have been interested in the extent to which organizational phenomena generalize across levels of analysis for quite some time. However, theoretical frameworks for developing homologous mul...

Smallpox vaccine–induced antibodies are necessary and sufficient for protection against monkeypox virus

Abstract: Vaccination with live vaccinia virus affords long-lasting protection against variola virus, the agent of smallpox. Its mode of protection in humans, however, has not been clearly defined. Here we report that vaccinia-specific B-cell responses are essential for protection of macaques from monkeypox virus, a variola virus ortholog. Antibody-mediated depletion of B cells, but not CD4+ or CD8+ T cells, abrogated vaccine-induced protection from a lethal intravenous challenge with monkeypox virus. In addition, passive transfer of human vaccinia-neutralizing antibodies protected nonimmunized macaques from severe disease. Thus, vaccines able to induce long-lasting protective antibody responses may constitute realistic alternatives to the currently available smallpox vaccine (Dryvax).

Human water needs

Abstract: Healthy humans regulate daily water balance remarkably well across their lifespan despite changes in biological development and exposure to stressors on hydration status. Acute or chronic body water deficits result when intakes are reduced or losses increase, but day-to-day hydration is generally well maintained so long as food and fluid are readily available. Total water intake includes drinking water, water in beverages, and water in food. Daily water needs determined from fluid balance, water turnover, or consumption studies provide similar values for a given set of conditions. A daily water intake of 3.7 L for adult men and 2.7 L for adult women meets the needs of the vast majority of persons. However, strenuous physical exercise and heat stress can greatly increase daily water needs, and the individual variability between athletes can be substantial.

Transforaminal lumbar interbody fusion: clinical and radiographic results and complications in 100 consecutive patients

Abstract: Objective:We retrospectively reviewed the results of 100 consecutive transforaminal lumbar interbody fusions (TLIFs) performed at one institution. The preoperative diagnoses included degenerative disk disease (55), spondylolisthesis (41; 22 isthmic, 19 degenerative), and degenerative adult scoliosis

Independent contributions of hypothermia and acidosis to coagulopathy in swine.

Abstract: : Background: Clinical coagulopathy occurs frequently in the presence of acidosis and hypothermia. The purpose of this study was to determine the relative contributions of acidosis and hypothermia to coagulopathy, as measured by current standard bedside and clinical laboratory analyses (i.e., bleeding time and pro- thrombin time). In addition, we investigated possible mechanisms of these effects using a modified prothrombin time test, thromboelastography, and thrombin kinetics analyses. An improved understanding of coagulopathy should facilitate hemorrhage control. Methods: Twenty-four pigs were randomly allocated into normal (pH, 7.4; 39 C), acidotic (pH, 7.1; 39 C), hypothermic (pH, 7.4; 32 Degrees C), and acidotic and hypothermic (pH, 7.1; 32 Degrees C) combined groups. Acidosis was induced by the infusion of 0.2N hydrochloric acid in lactated Ringer s solution. Hypothermia was induced by using a blanket with circulating water at 4 Degrees C. Development of a clinical coagulopathy was defined as a significant increase in splenic bleeding time. Measurements were compared before (pre) and 10 minutes after (post) the target condition was achieved. Results: Acidosis, hypothermia, or both caused the development of coagulopathy, as indicated by 47%, 57%, and 72% increases in splenic bleeding time (p less than 0.05, pre vs. post). Plasma fibrinogen concentration was decreased by 18% and 17% in the acidotic and combined groups, respectively, but not in the hypothermic group. Hypothermia caused a delay in the onset of thrombin generation, whereas acidosis primarily caused a decrease in thrombin generation rates. At 4 minutes quench time, thrombin generation in the acidotic, hypothermic, and combined groups were 47.0%, 12.5%, and 5.7%, respectively, of the value in the control group. There were no changes in serum tumor necrosis factor- and interleukin-6 in any group during the study.

Synthesis and application of poly(phenylene ethynylene)s for bioconjugation : a conjugated polymer-based fluorogenic probe for proteases

Abstract: A set of carboxylate-functionalized poly(phenylene ethynylene)s (PPEs) has been synthesized in which the carboxylic acid groups are separated from the polymer backbone by oligo(ethylene glycol) spacer units. These polymers are soluble in water and organic solvents and have photophysical properties that are sensitive to solvent conditions, with high salt content and the absence of surfactant promoting the formation of aggregates of relatively low quantum yield and long fluorescence lifetime. Quenching of these materials by the dinitrophenyl (DNP) chromophore (K(SV) approximately 10(4)) is also highly solvent-dependent. The presence of carboxylate groups far from the polymer backbone appended to each repeating unit allows for the postpolymerization modification of these PPEs with peptides by methods analogous to those described for carboxylate-functionalized small-molecule dyes. Covalent attachment of the fluorescence-quenching 14-mer Lys(DNP)-GPLGMRGLGGGGK to the PPE results in a nonemissive substrate whose fluorescence is restored upon treatment with trypsin. The rate of fluorescence turn-on in this case is increased 3-fold by the presence of surfactant, though the actual rate of peptide hydrolysis remains the same. A small-molecule mimic of the polymer-peptide system shows a smaller fluorescence enhancement upon treatment with trypsin, illustrating the value of polymer-based amplification in this sensory scheme.

Clade Replacements in Dengue Virus Serotypes 1 and 3 Are Associated with Changing Serotype Prevalence

Abstract: The evolution of dengue virus (DENV) is characterized by phylogenetic trees that have a strong temporal structure punctuated by dramatic changes in clade frequency. To determine the cause of these large-scale phylogenetic patterns, we examined the evolutionary history of DENV serotype 1 (DENV-1) and DENV-3 in Thailand, where gene sequence and epidemiological data are relatively abundant over a 30-year period. We found evidence for the turnover of viral clades in both serotypes, most notably in DENV-1, where a major clade replacement event took place in genotype I during the mid-1990s. Further, when this clade replacement event was placed in the context of changes in serotype prevalence in Thailand, a striking pattern emerged; an increase in DENV-1 clade diversity was associated with an increase in the abundance of this serotype and a concomitant decrease in DENV-4 prevalence, while clade replacement was associated with a decline in DENV-1 prevalence and a rise of DENV-4. We postulate that intraserotypic genetic diversification proceeds at times of relative serotype abundance and that replacement events can result from differential susceptibility to cross-reactive immune responses.

Running performance differences between men and women:an update.

Abstract: More than a decade ago it was reported in the journal Nature that the slope of improvement in the men's and women's running records, extrapolated from mean running velocity plotted against historical time, would eventually result in a performance intersection of the sexes across a variety of running distances. The first of these intersections was to occur for 42 000 m before the 21st century. Most of the error in this prediction is probably explained by the linear mathematical treatment and extrapolation of limited performance data, since including world record-setting running performances for women before and after 1985 results in a non-linear data fit. The reality of early, disproportionate improvements in women's running that gave the appearance of an impending convergence with men is best explained by an historical social sports bias. Women's times have now reached a plateau similar to that observed for men at comparative performance milestones in the marathon. Sex differences at distances from 100 to 10 000 m show similar trends. The remaining sex gaps in performance appear biological in origin. Success in distance running and sprinting is determined largely by aerobic capacity and muscular strength, respectively. Because men possess a larger aerobic capacity and greater muscular strength, the gap in running performances between men and women is unlikely to narrow naturally.

Laser-induced breakdown spectroscopy (LIBS): a promising versatile chemical sensor technology for hazardous material detection

Abstract: A series of laboratory experiments have been performed highlighting the potential of laser-induced breakdown spectroscopy (LIBS) as a versatile sensor for the detection of terrorist threats. LIBS has multiple attributes that provide the promise of unprecedented performance for hazardous material detection and identification. These include: 1) real-time analysis, 2) high sensitivity, 3) no sample preparation, and 4) the ability to detect all elements and virtually all hazards, both molecular and biological. We have used LIBS to interrogate a variety of different target samples, including explosives, chemical warfare simulants, biological agent simulants, and landmine casings. We have used the acquired spectra to demonstrate discrimination between different chemical warfare simulants, including those on soil backgrounds. A linear correlation technique permits discrimination between an anthrax surrogate and several other biomaterials such as molds and pollens. We also use broadband LIBS to identify landmine casings versus other plastics and environmental clutter materials. A new man-portable LIBS system developed as a collaborative effort between the U.S. Army Research Laboratory and Ocean Optics, Inc., is described and several other schemes for implementing LIBS sensors for homeland security and force protection are discussed.

Detecting software attacks by monitoring electric power consumption patterns

Abstract: Software attacks such as worms and viruses are detected in an electronic device by monitoring power consumption patterns. In a first embodiment, software attacks are detected by an increase in power consumption. The increased power consumption can be caused by increased network traffic, or by increased activity in the microprocessor. Monitoring power consumption is particularly effective for detecting DOS/flooding attacks when the electronic device is in an idle state. In a second embodiment, a power consumption signal is converted to the frequency domain (e.g., by fast Fourier transform). The highest amplitude frequencies are identified. Specific software attacks produce characteristic frequencies in the power consumption signal. Software attacks are therefore detected by matching the highest amplitude frequencies with frequencies associated with specific worms and viruses. Identification of a particular software attack typically requires matching of 3 or more of the highest amplitude frequencies, and, optionally, amplitude information.

Complications of Nonoperative Management of High-Grade Blunt Hepatic Injuries

Abstract: : Nonoperative management of blunt hepatic injuries is highly successful. Complications associated with high- grade injuries, however, have not been well characterized. The purpose of the present study was therefore to define hepatic-related complications and associated treatment modalities in patients undergoing non-operative management of high-grade blunt hepatic injuries. Methods: Three hundred thirty-seven patients from two regional Level I trauma centers with grade 3 to 5 blunt hepatic injuries during a 40-month period were reviewed. Complications and treatment of hepatic-related complications in patients not requiring laparotomy in the first 24 hours were identified. Results: Of 337 patients with a grade 3 to 5 injury, 230 (68%) were managed non-operatively. There were 37 hepatic-related complications in 25 patients (11%); 63% (5 of 8) of patients with grade 5 injuries developed complications, 21% (19 of 92) of patients with grade 4 injuries, but only 1% (1 of 130) of patients with grade 3 injuries. Complications included bleeding in 13 patients managed by angioembolization (n = 12) and laparotomy (n = 1), liver abscesses in 2 patients managed with computed tomography-guided drainage (n = 2) and subsequent laparotomy (n = 1). In one patient with bleeding, hepatic necrosis followed surgical ligation of the right hepatic artery and required delayed hepatic lobectomy. Sixteen biliary complications were managed with endoscopic retrograde cholangiopancreatography and stenting (n = 7), drainage (n = 5), and laparoscopy (n = 4). Three patients had suspected abdominal sepsis and underwent a negative laparotomy, whereas an additional three patients underwent laparotomy for abdominal compartment syndrome. Conclusion: Nonoperative management of high-grade liver injuries can be safely accomplished. Mortality is low; however, complications in grade 4 and 5 injuries should be anticipated and may require a combination of operative and nonoperative management strategies.

Metabolic Consequences of Muscle Disuse Atrophy

Abstract: In response to decreased usage, skeletal muscle undergoes an adaptive reductive remodeling. This adaptive response has been found with disuse during human spaceflight, rat spaceflight, rat hind-limb unloading, bed rest, and aging. The reductive remodeling of skeletal muscle with disuse is largely independent of the reason for the disuse. The process involves more than a transition from slow to fast myosin fiber types. There are associated metabolic changes including a fuel shift toward glycolysis, decreased capacity for fat oxidation, and energy substrate accumulation in the atrophied muscles. Glycolysis is very effective for high-intensity short-duration acute activities, but if sustained output is needed, an energy profile where fat use is favored rather than compromised is desirable. For astronauts, there is a need to maintain as much functional capacity as possible during spaceflight for extravehicular activities. The shift toward increased activity of the glycolytic enzymes in atrophied muscle is accommodated by an increase in gluconeogenic capacity in the liver.

Protective Immunization against Inhalational Anthrax: A Comparison of Minimally Invasive Delivery Platforms

Abstract: A new anthrax vaccine under clinical investigation is based on recombinant Bacillus anthracis protective antigen (rPA). Here, we investigated microneedle-based cutaneous and nasal mucosal delivery of rPA in mice and rabbits. In mice, intradermal (id) delivery achieved up to 90% seroconversion after a single dose, compared with 20% after intramuscular (im) injection. Intranasal (inl) delivery of a liquid formulation required 3 doses to achieve responses that were comparable with those achieved via the id or im routes. In rabbits, id delivery provided complete protection against aerosol challenge with anthrax spores; in addition, novel powder formulations administered inl provided complete protection, whereas a liquid formulation provided only partial protection. These results demonstrate, for the first time, that cutaneous or nasal mucosal administration of rPA provides complete protection against inhalational anthrax in rabbits. The novel vaccine/device combinations described here have the potential to improve the efficacy of rPA and other biodefense vaccines.

Economic impact of dengue fever/dengue hemorrhagic fever in thailand at the family and population levels

Abstract: Dengue fever and dengue hemorrhagic fever constitute a substantial health burden on the population in Thailand. In this study, the impact of symptomatic dengue virus infection on the families of patients hospitalized at the Kamphaeng Phet Provincial Hospital with laboratory-confirmed dengue in 2001 was assessed, and the disability-adjusted life years (DALYs) lost for fatal and non-fatal cases of dengue were calculated using population level data for Thailand. When we accounted for the direct cost of hospitalization, indirect costs due to loss of productivity, and the average number of persons infected per family, we observed a financial loss of approximately US$61 per family, which is more than the average monthly income in Thailand. The DALYs were calculated using select results from a family level survey, and resulted in an estimated 427 DALYs/million population in 2001. This figure is of the same order of magnitude as the impact of several diseases currently given priority in southeast Asia, such as the tropical cluster (trypanosomiasis, Chagas disease, schistosomiasis, leishmaniasis, lymphatic filariasis, and onchocerciasis), malaria, meningitis, and hepatitis. These results indicate that dengue prevention, control, and research should be considered equally important as that of diseases currently given priority.

Mortality from isolated civilian penetrating extremity injury.

Abstract: Background Although studies have ascertained that ten percent of soldiers killed in battle bleed to death from extremity wounds, little data exists on exsanguination and mortality from extremity injuries in civilian trauma. This study examined the treatment course and outcomes of civilian patients who appear to have exsanguinated from isolated penetrating extremity injuries. Methods Five and 1/2 years' data (Aug 1994 to Dec 1999) were reviewed from two Level I trauma centers that receive 95% of trauma patients in metropolitan Houston, TX. Records (hospital trauma registries, emergency medical system (EMS) and medical examiner data) were reviewed on all patients with isolated extremity injuries who arrived dead at the trauma center or underwent cardiopulmonary resuscitation (CPR) or emergency center thoracotomy (ECT). Results Fourteen patients meeting inclusion criteria were identified from over 75,000 trauma emergency center (EC) visits. Average age was 31 years and 93% were males. Gunshot wounds accounted for 50% of the injuries. The exsanguinating wound was in the lower extremity in 10/14 (71%) patients and proximal to the elbow or knee in 12/14 (86%). Ten (71%) had both a major artery and vein injured; one had only a venous injury. Prehospital hemorrhage control was primarily by gauze dressings. Twelve (86%) had "signs of life" in the field, but none had a discernable blood pressure or pulse upon arrival at the EC. Prehospital intravenous access was not obtained in 10 patients (71%). Nine patients underwent ECT, and nine were initially resuscitated (eight with ECT and one with CPR). Those undergoing operative repair received an average of 26 +/- 14 units of packed red blood cells. All patients died, 93% succumbing within 12 hours. Conclusion Although rare, death from isolated extremity injuries does occur in the civilian population. The majority of injuries that lead to immediate death are proximal injuries of the lower extremities. The cause of death in this series appears to have been exsanguination, although definitive etiology cannot be discerned. Intravenous access was not obtainable in the majority of patients. Eight patients (57%) had bleeding from a site that anatomically might have been amenable to tourniquet control. Patients presenting to the EC without any detectable blood pressure and who received either CPR or EC thoracotomy all died.

Hypohydration impairs endurance exercise performance in temperate but not cold air

Abstract: This study compared the effects of hypohydration (HYP) on endurance exercise performance in temperate and cold air environments. On four occasions, six men and two women (age = 24 +/- 6 yr, height = 170 +/- 6 cm, weight = 72.9 +/- 11.1 kg, peak O2 consumption = 48 +/- 9 ml.kg(-1).min(-1)) were exposed to 3 h of passive heat stress (45 degrees C) in the early morning with [euhydration (EUH)] or without (HYP; 3% body mass) fluid replacement. Later in the day, subjects sat in a cold (2 degrees C) or temperate (20 degrees C) environment with minimal clothing for 1 h before performing 30 min of cycle ergometry at 50% peak O2 consumption followed immediately by a 30-min performance time trial. Rectal and mean skin temperatures, heart rate, and ratings of perceived exertion measurements were made at regular intervals. Performance was assessed by the total amount of work (kJ) completed in the 30-min time trial. Skin temperature was significantly lower in the cold compared with the temperate trial, but there was no independent effect of hydration. Rectal temperature in both HYP trials was higher than EUH after 60 min of exercise, but the difference was only significant within the temperate trials (P EUH) and at 60 min within the cold trial (HYP > EUH) (P < 0.05). Ratings of perceived exertion increased over time with no differences among trials. Total work performed during the 30-min time trial was not influenced by environment but was less (P < 0.05) for HYP than EUH in the temperate trials. The corresponding change in performance (EUH-HYP) was greater for temperate (-8%) than for cold (-3%) (P < 0.05). These data demonstrate that 1) HYP impairs endurance exercise performance in temperate but not cold air but 2) cold stress per se does not.

Bacterial genome adaptation to niches: Divergence of the potential virulence genes in three Burkholderia species of different survival strategies

Abstract: Two closely related species Burkholderia mallei (Bm) and Burkholderia pseudomallei (Bp) are serious human health hazards and are potential bio-warfare agents, whereas another closely related species Burkholderia thailandensis (Bt) is a non-pathogenic saprophyte. To investigate the genomic factors resulting in such a dramatic difference, we first identified the Bm genes responsive to the mouse environment, and then examined the divergence of these genes in Bp and Bt. The genes down-expressed, which largely encode cell growth-related proteins, are conserved well in all three species, whereas those up-expressed, which include potential virulence genes, are less well conserved or absent notably in Bt. However, a substantial number of up-expressed genes is still conserved in Bt. Bm and Bp further diverged from each other in a small number of genes resulting from unit number changes in simple sequence repeats (ssr) in the homologs. Our data suggest that divergent evolution of a small set of genes, rather than acquisition or loss of pathogenic islands, is associated with the development of different life styles in these bacteria of similar genomic contents. Further divergence between Bm and Bp mediated by ssr changes may reflect different adaptive processes of Bm and Bp fine-tuning into their host environments.