Showing papers by "United States Department of the Army published in 1996"

Virtual spaces and real world places: transfer of route knowledge

Abstract: It has been widely suggested, but rarely demonstrated, that virtual environments (VEs) are effective training media. The purpose of this investigation was to evaluate how well a VE model of a complex office building trained individuals to navigate in the actual building. Sixty participants studied route directions and landmark photographs, then rehearsed the route using either the VE model, the actual building, or verbal directions and photographs. The VE model was presented in real time via a head-tracked display. Half of the participants in each rehearsal group also studied route maps. Everyone's route knowledge was then measured in the actual building. Building configuration knowledge was also measured. VE rehearsal produced more route knowledge than verbal rehearsal, but less than with rehearsal in the actual building. Type of rehearsal had no effect on configuration knowledge. Map study influenced neither route nor configuration knowledge. These results suggest that VEs that adequately represent real world complexity can be effective training media for learning complex routes in buildings, and should be considered whenever the real world site is unavailable for training.

A New Paradigm for Leadership: An Inquiry into Transformational Leadership.

Abstract: : The preponderance of research on leadership stems from either of the two dominant models of leadership. The transactional model and the transformational model have provided the backbone for a theoretical understanding of leadership. This report views both of these models through a factor analytic framework. It also provides answers to a series of fundamental questions concerning what we know about leadership, what we do not know, and identifies areas for further research.

Toxicology and pharmacology of the chemical warfare agent sulfur mustard.

Abstract: There have been reports of chemical attacks in which sulfur mustard might have been used (a) on Iranian soldiers and civilians during the Gulf War in 1984 and 1985 and (b) in an Iraqi chemical attack on the Iranian-occupied village of Halbja in 1988, resulting in many civilian casualties. Heavy use of chemical warfare in Afghanistan by the Soviet military is a recent innovation in military tactics that has been highly successful and may ensure further use of chemical agents in future military conflicts and terrorist attacks as a profitable adjunct to conventional military arms. Mustard is a poisonous chemical agent that exerts a local action on the eyes, skin, and respiratory tissue, with subsequent systemic action on the nervous, cardiac, and digestive systems in humans and laboratory animals, causing lacrimation, malaise, anorexia, salivation, respiratory distress, vomiting, hyperexcitability, and cardiac distress. Under extreme circumstances, dependent upon the dose and length of exposure to the agent, necrosis of the skin and mucous membranes of the respiratory system, bronchitis, bronchopneumonia, intestinal lesions, hemoconcentration, leucopenia, convulsions with systemic distress, and death occur. Severe mustard poisoning in humans is associated with systemic injury, which is manifested as headache, epigastric distresses, anorexia, diarrhea, and cachexia and is usually observed at mustard doses of 1000 mg/min/m3 with damage to hematopoietic tissues and progressive leucopenia. Sulfur mustard is a cell poison that causes disruption and impairment of a variety of cellular activities that are dependent upon a very specific integral relationship. These cytotoxic effects are manifested in widespread metabolic disturbances whose variable characteristics are observed in enzymatic deficiencies, vesicant action, abnormal mitotic activity and cell division, bone marrow disruption, disturbances in hematopoietic activity, and systemic poisoning. Indeed, mustard gas readily combines with various components of the cell such as amino acids, amines, and proteins. Although evidence of an association between lung cancer and mustard gas encountered on the battlefields of World War I is at best suggestive if not problematical (Case and Lea, 1955; Beebe, 1960; Norman, 1975), the epidemiological data accumulated from the poison gas factories in Japan (Yamada et al., 1953; Wada et al., 1968; Inada et al., 1978; Shigenobu, 1980; Nishimoto et al., 1983; Hirono et al., 1984; Takuoka et al., 1986), in Germany (Weiss, 1958; Hellmann, 1970a; Weiss and Weiss, 1975; Klehr, 1984) and in England (Manning et al., 1981; Easton et al., 1988) are substantial (International Agency for Research on Cancer, 1975). Unfortunately, attempts to seek confirmatory and substantial evidence in laboratory animals such as mice (Boyland and Horning, 1949; Heston, 1950; Heston, 1953a; McNamara et al., 1975) and rats (Griffin et al., 1951; McNamara et al., 1975; Sasser et al., 1996) have not been consistent. Sulfur mustard has been shown to be mutagenic in a variety of different species using many different laboratory techniques from fruit flies, microorganisms and mammalian cell cultures (Fox and Scott, 1980). Evidence is slowly accumulating from human data (Hellmann, 1970a; Lohs, 1975; Wulf et al., 1985). Evidence for the teratogenicity of mustard has been negative in assessment of fetotoxicity and adverse effects of mustard on the reproductive potential of both human and animal studies. Indeed, investigations of women adversely affected by mustard are minimal because most of the studies have been performed on former men employees of poison gas factories and have been negative or questionable. We have recently emphasized the need to assess the affect of a suspected teratogen on maternal toxicity in laboratory animals before any conclusions can be made.(ABSTRACT TRUNCATED)

Detection of Pathogenic and Non‐pathogenic Bacteria by Matrix‐assisted Laser Desorption/ Ionization Time‐of‐flight Mass Spectrometry

Abstract: The proteins isolated from the whole cells of bacterial pathogens and related non-pathogenic simulants were analyzed directly, with minimal sample preparation by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Inspection of mass spectrometric profiles obtained from direct MALDI-MS analysis of the protein extracts revealed specific biomarkers for individual bacterial cells. The observed biomarkers enabled us not only to detect pathogenic bacteria (Bacillus anthracis, Yersinia pestis and Brucella melitensis), but also to distinguish them from the corresponding non-pathogenic species. By examining a series of strains of several Bacillus species (anthracis, thuringiensis, cereus and subtilis), it was possible to derive genus, species and strain-specific biomarkers from the measured molecular masses of the intact proteins. Additional series of biomarkers were obtained from direct mass spectrometric analysis of tryptic digests of the protein extracts. The application of this technique for rapid chemotaxonomic classification of microorganisms is demonstrated.

NT-3 and/or BDNF therapy prevents loss of auditory neurons following loss of hair cells.

Abstract: Destruction of auditory hair cells results in a subsequent loss of auditory neurons. In situ hybridization and neuronal cell culture studies as well as analyses of the inner ears of neurotrophin and neurotrophin receptor gene knockout mice have shown that NT-3 and BDNF mediate both the development and survival of auditory neurons. In this study guinea pigs were exposed to the ototoxic combination of an aminoglycoside antibiotic and a loop diuretic and then received 8 weeks of intracochlear infusion of either NT-3, BDNF or NT-3 + BDNF to determine whether site-specific application of these neurotrophins could prevent the loss of auditory neurons that follows a loss of auditory hair cells. Infusion of either NT-3 or NT-3 + BDNF into the scala tympani resulted in a > 90% survival of auditory neurons while BDNF infusion yielded a 78% survival rate, compared with a 14-24% neuronal survival rate in untreated ototoxin-exposed cochleae. These results show that loss of auditory neurons that occurs subsequent to a loss of auditory hair cells can be prevented by in vivo neurotrophin therapy with either NT-3 or BDNF.

Rapid identification of bacteria by direct matrix-assisted laser desorption/ionization mass spectrometric analysis of whole cells.

Abstract: Several characteristic ions were observed during the direct analysis of a variety of both gram-negative and gram-positive intact bacterial cells by the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) technique. The entire process, involving absolutely no sample processing, could be completed in less than ten minutes. A number of specific biomarkers, generated reproducibly for each type of cell from the corresponding mass spectrum, permitted the identification, as well as the distinction, of pathogenic bacteria from their non-pathogenic counterparts. In addition, individual strains of a specific organism could also be differentiated easily. Some of these biomarkers correspond to those observed earlier during the MALDI-MS analysis of protein extracts of the same bacteria. This approach, which can yield valuable data for rapid classification and detection of microorganisms, represents a substantial breakthrough for rapid screening of environmental as well as biological samples

Chitosan Film Acylation and Effects on Biodegradability

Abstract: Chitosan films were acylated under heterogeneous conditions in methanol with acetic and hexanoic anhydrides and characterized by proton nuclear magnetic resonance, elemental analysis, and multiple internal reflective Fourier transform infrared spectroscopy. The disappearance of the NH2 vibrational band at 1590 cm-1, the appearance of the amide II band at 1555 cm-1, and the relatively low intensity of the ester band at 1735 cm-1 showed that acylation at the surface was site-selective for the amino (N) functionalities. Furthermore, N-acylation at the surface region appeared complete within 1 h. The acylated chitosan films were fractionated in aqueous acetic acid for compositional analysis. Acetylation of chitosan films for 3 h gave 52% of aqueous acetic acid insoluble chitin (outer film region) and 48% unreacted chitosan. In contrast, 3 h hexanoylation reactions resulted in 99% aqueous acetic acid soluble product. Thus, film N-acetylation was more rapid than N-hexanoylation. Moreove...

Mechanisms of Heat Exchange: Biophysics and Physiology

Abstract: The sections in this article are: 1 Human Heat Balance Equation 2 Independent Variables Affecting the Thermal Environment 2.1 Ambient Temperature 2.2 Dew Point Temperature and Ambient Vapor Pressure 2.3 Air and Fluid Movement 2.4 Mean Radiant Temperature and Effective Radiant Field 2.5 Clothing Insulation 2.6 Barometric Pressure 3 Peripheral Factors to Heat Exchange 3.1 Mean Skin Temperature 3.2 Skin Wettedness 3.3 Body Heat Storage and Rate of Change of Mean Body Temperature 3.4 Metabolic Energy 4 Sensible Heat Exchange by Radiation and Convection 4.1 Operative Temperature 4.2 Clothing Properties Effective in Sensible Heat Exchange 5 Radiation Exchange 5.1 Mean Radiant Temperature and Effective Radiant Field 6 Convective Heat Exchange 6.1 Heat Transfer Theory 6.2 Measurement of the Convective Heat Transfer Coefficient 6.3 Effect of Altitude (Barometric Pressure) on Convective Heat Loss 7 Evaporative Heat Exchange 7.1 Direct Measurement of Evaporative Heat Loss 8 Psychrometrics of the Human Heat Balance Equation 8.1 Lewis Relation: Interpretation of Wet-Bulb Temperature and Enthalpy 8.2 Generalization to Energy Transfer between Humans and the Environment 8.3 Enthalpy of the Human Environment 8.4 Enthalpy and the Rational Indices of the Human Environment 9 Pierce Two-Node Model of Thermoregulation 9.1 The Passive State 9.2 The Control System 9.3 Initial Warm and Cold Signals 9.4 Control of Skin Blood Flow 9.5 Control of the Whole-Body Sweating Drive 9.6 Control of the Skin Shell Properties 9.7 Control of Shivering 10 Heat Loss Factors in Warm and Cold Environments: Physiology 10.1 Heat and Mass Transfer from the Body to the Environment 10.2 Body Motion 10.3 Thermal Aspects 10.4 Thermoregulatory Control Relative to Heat Loss Factors 10.5 Physiological Responses of Heat Loss by Thermal Radiation and Adaptive Response 11 Heat Loss in Special Environments 11.1 Hypobaric Environments 11.2 Hyperbaric Environments 11.3 Aquatic Environments 11.4 Heat Exchange in Spacecraft

Immunomagnetic-electrochemiluminescent detection of Escherichia coli O157 and Salmonella typhimurium in foods and environmental water samples.

Abstract: Hemorrhagic Escherichia coli O157:H7 strains and other virulent enteric pathogens can pose a serious health threat in tainted meats, poultry, and even drinking water. Traditional culture-based methods for assay of enteric pathogens in foods and water sources are relatively slow, and results can be ambiguous. Immunomagnetic separation (IMS) and detection methods have been investigated and appear promising for rapid bacterial assay of foods and environmental samples. In this work, a commercial sensor which combines IMS with electrochemiluminescence (ECL) detection is evaluated for detection of E. coli O157 and Salmonella typhimurium in foods and fomites. Results indicate that detection limits are in the range of 100 to 1,000 bacteria per ml in pristine buffer for E. coli O157 and S. typhimurium, respectively, or 1,000 to 2,000 bacteria per ml in food samples (depending on the sample) and that total processing and assay time is rapid (< 1 h) even in food samples. An immunologic "hook" or high-antigen-concentration prozone effect was observed above 10(4) and 10(5) bacteria per ml for E. coli O157 and S. typhimurium, respectively. IMS was accomplished in milk, juices, serum, supernatant fluids from ground beef, finely minced chicken, and fish suspensions as well as several freshwater sources and followed by ECL assay. Some samples, especially fish, gave unexpectedly high background ECL. Conversely, low ECL intensity was observed in nonfat and 2% fat milk samples, which appeared to be related to binding or entrapment of the antibody-coated magnetic beads by particulates in the milk, as revealed by microscopy. Results of this evaluation suggest the feasibility of immunomagnetic-ECL methodology for rapid, sensitive, and facile preliminary screening of various foods and fomites for the presence of virulent enteric pathogens.

Fraction 1 capsular antigen (F1) purification from Yersinia pestis CO92 and from an Escherichia coli recombinant strain and efficacy against lethal plague challenge.

Abstract: As a first step in formulating an improved plague vaccine, we developed a simple purification strategy that produced high yields of pure cell-associated and culture supernatant-derived fraction 1 capsular antigen (F1) from both avirulent Yersinia pestis C092 (Pgm- Lcr-) and an Escherichia coli F1-producing recombinant strain. Cell-associated F1 was partially purified by sequential ammonium sulfate precipitations of a sodium chloride extract of acetone-dried bacteria harvested from broth cultures. Cell-free F1 was precipitated directly from culture supernatants with a single application of 30% ammonium sulfate. By exploiting the aggregative property of F1, large quantities of purified high-molecular-weight F1 species from both cell extracts and supernatants were isolated in the void volume of a preparative gel filtration column. Highly purified, endotoxin-free F1, combined with two different adjuvants, induced very high F1 titers in mice and protected them against either subcutaneous (70 to 100% survival) or aerosol (65 to 84% survival) challenge with virulent organisms. This protection was independent of the source of the antigen and the adjuvant used. F1-induced protection against both subcutaneous and aerosol challenge was also significantly better than that conferred by immunization with the licensed killed whole-cell vaccine. Our results indicate that F1 antigen represents a major protective component of previously studied crude capsule preparations, and immunity to F1 antigen provides a primary means for the host to overcome plague infection by either the subcutaneous or respiratory route.

Ultrashort pulse propagation at the photonic band edge : large tunable group delay with minimal distortion and loss

Abstract: We examine optical pulse propagation through a 30-period, GaAs/AlAs, one-dimensional, periodic structure at the photonic band-edge transmission resonance. We predict theoretically---and demonstrate experimentally---an approximate energy, momentum, and form invariance of the transmitted pulse, as well as large group index (up to 13.5). The group index is tunable and many orders of magnitude more sensitive to variation in material refractive index than for bulk material. We interpret this observation in terms of time-dependent electromagnetic states of the pulse-crystal system.

Eyetracker control of heads-up displays

Abstract: The invention consists of an eyetracker, a display driver, an adaptive display interface controller, and a digital computer. A user of the invention can operate a heads-up display (or a head mounted display) with an eyetracker, leaving his hands free to perform a manual control task. The user selects a display element from an array of choices on the heads-up display by gazing at an element while he activates a confirming mechanism. Both tasks share a common visual working area with overlaid visual images, and task interference is reduced since eye-movements and visual attention are dedicated to the same display surface. The adaptive display interface automatically aids the user in display operations during high manual task loading. The adaptive interface is driven by an electronic Expert System on human visual processes programmed as a Fuzzy Logic controller. The controller generates display cueing aids, under computer control, in response to the erratic eye movement patterns that occur during cognitive conflict. The cueing aids help the user to operate the display with a sequence of discrete eye gazes and confirming actions which only momentarily interrupt the manual control task. As cueing aids, the invention provides a timing logic for element enhancement, and display markers for task feedback. While the aids would be disruptive at low cognitive loading, they provide necessary timing and memory prompts at high loadings. The element enhancement timing logic allows the user to momentarily look at the display and then return his attention to the tracking task before executing confirmation. The display cues show the user where he is looking on the display relative to the element to be selected.

Parallel document clustering process

Abstract: A computer information processing system utilizes parallel processors for organizing and clustering a large number of documents into a large number of clusters for information analysis and retrieval. After the documents are translated into electronic digital documents, each document is converted into a vector based on weighted list of the occurence of different words and terms that appear in the document. The document vectors are grouped together into cluster vectors on different parallel processors according to similarities. New document vectors are simultaneously compared with existing cluster vectors in the different parallel processors.

Motion and sound monitor and stimulator

Abstract: A movement monitor and stimulator may prevent death in human infants from sudden infant death syndrome (SIDS). Recent medical studies indicate a SIDS victim's breathing may be resuscitated by immediate stimulation. The sound and/or movement monitor and stimulator may have a base member configured as a fluid-filled sensing pad for supporting an infant and a transducer for detecting movement or acoustic activity (e.g., heart beat, breathing, voice and motion sounds). A stimulator may move the base member to stimulate movement in the object when output from the transducer corresponds to no sound and/or movement from the object, or indicates a dangerous change in monitored condition, such as the decrease in metabolic rate indicative of the onset of sleep. The stimulator may also be applied in a more gentle fashion to soothe and quiet an infant that has been awakened unexpectedly. The transducer may be a pressure transducer in fluid communication with the fluid interior of the sensing pad. Alternatively, a piezoelectric sheet operatively connected to a surface of the sensing pad may detect movement and movement cessation. An alarm may provide an audible and/or visual indication to third parties when there is no movement from the object. A transmitter may continuously transmit the sensor's output to a remote location for monitoring. A remote monitor may transmit heart and breathing sounds and may also have lights indicating motion and acoustic activity to indicate the infant is breathing.

Method of fabricating an air-filled waveguide on a semiconductor body

Abstract: A method of using layers of gold metallization and a thick film coating of photo-sensitive material to form an air-filled microwave waveguide structure on the outer surface of a semiconductor body, such as a monolithic microwave integrated circuit commonly referred to as an MMIC, so that the waveguide can be coupled to the active and passive devices of the MMIC. First, a patterned metallization layer is formed on a substrate. A mold of a waveguide is fabricated by masking and then etching another metallization layer. The mold is turned over face down on the patterned metallization layer and bonded to the patterned metallization layer, Then, any unnecessary material is etched away.

Electronically graded multilayer ferroelectric composites

Abstract: A laminated ceramic ferroelectric material has adjacent layers of Barium ontium Titanate (BSTO)--oxide composite stacked in order of descending oxide content and sized in thickness to produce a generally equal capacitance across each layer, resulting in a material having a graded dielectric constant for use in phased array antenna, for example. The oxides are from the metallic oxide group consisting of alumina, zirconia and magnesia and the layers are produced by tape casting.

Evanescent light-wave atom mirrors, resonators, waveguides, and traps

Abstract: Publisher Summary This chapter presents an overview of atom mirrors, resonators, waveguides, and traps that operate for the most part on the evanescent light-wave mechanism for atom manipulation. For many years, it has been known that light can be used to trap and manipulate small dielectric particles and atoms. In particular, the intense coherent light of lasers has been used to cool neutral atoms down to the micro-Kelvin and now even the nano-Kelvin regimes. The chapter discusses several convex, evanescent light-wave traps or guides in which at least one field is red-detuned, and hence attractive but a centrifugal force or a blue-detuned field provides a repulsive counterforce to allow the atoms to remain confined in stable orbits around the convex, dielectric, and optical resonator. The chapter focuses on the use of the evanescent field for making atom mirrors, resonators, waveguides, and traps. One of the principal experimental drawbacks of the evanescent light-wave mirror is that it requires quite high laser power to produce a sufficiently large potential barrier to reflect atoms with any realistic component of velocity normal to the surface, while not introducing an unacceptable degree of spontaneous emission probability.

Cloning and expression of a gene encoding a bacterial enzyme for decontamination of organophosphorus nerve agents and nucleotide sequence of the enzyme.

Abstract: Organophosphorus acid (OPA) anhydrolase enzymes have been found in a wide variety of prokaryotic and eukaryotic organisms. Interest in these enzymes has been prompted by their ability to catalyze the hydrolysis of toxic organophosphorus cholinesterase-inhibiting compounds, including pesticides and chemical nerve agents. The natural substrates for these enzymes are unknown. The gene (opaA) which encodes an OPA anhydrolase (OPAA-2) was isolated from an Alteromonas sp. strain JD6.5 EcoRI-lambda ZAPII chromosomal library expressed in Escherichia coli and identified by immunodetection with anti-OPAA-2 serum. OPA anhydrolase activity expressed by the immunopositive recombinant clones was demonstrated by using diisopropylfluorophosphate (DFP) as a substrate. A comparison of the recombinant enzyme with native, purified OPAA-2 showed they had the same apparent molecular mass (60 kDa), antigenic properties, and enzyme activity against DFP and the chemical nerve agents sarin, soman, and O-cyclohexyl methylphosphonofluoridate. The gene expressing this activity was found in a 1.74-kb PstI-HindIII fragment of the original 6.1-kb EcoRI DNA insert. The nucleotide sequence of this PstI-HindIII fragment revealed an open reading frame of 1,551 nucleotides, coding for a protein of 517 amino acid residues. Amino acid sequence comparison of OPAA-2 with the protein database showed that OPAA-2 is similar to a 647-amino-acid sequence produced by an open reading frame which appears to be the E. coli pepQ gene. Further comparison of OPAA-2, the E. coli PepQ protein sequence, E. coli aminopeptidase P, and human prolidase showed regions of different degrees of similarity or functionally conserved amino acid substitutions. These findings, along with preliminary data confirming the presence of prolidase activity expressed by OPAA-2, suggest that the OPAA-2 enzyme may, in nature, be used in peptide metabolism.

Sediment retention in a bottomland hardwood wetland in Eastern Arkansas

Abstract: One of the often-stated functions of wetlands is their ability to remove sediments and other particulates from water, thus improving water quality in the adjacent aquatic system. However, actual rates of suspended sediment removal have rarely been measured in freshwater wetland systems. To address this issue, suspended sediment dynamics were measured in a 85-km2 bottomland hardwood (BLH) wetland adjacent to the highly turbid Cache River in eastern Arkansas during the 1988–1990 water years. A suspended sediment mass balance was calculated using depth-integrated, flow-weighted daily measurements at wetland inflow and outflow points. Over the three-year period, suspended sediment load decreased an average of 14% between upstream and downstream sampling points. To test the idea that the suspended sediments were retained by the adjacent wetland and to determine what portion of the BLH forest was most responsible for retaining the suspended sediments, concurrent measurements of sediment accretion were made at 30 sites in the wetland using feldspar clay marker horizons, sedimentation disks, the137cesium method, and dendrogeomorphic techniques. Sedimentation rates exceeding 1 cm/yr were measured in frequently flooded areas dominated byNyssa aquatica andTaxodium distichum. Maximum sedimentation rates did not occur on the natural levee, as would be predicted by classical fluvial geomorphology, but in the “first bottom,” where retention time of the water reached a maximum. Multiple regression was used to relate sedimentation rates with several physical and biological factors. A combination of distance from the river, flood duration, and tree basal area accounted for nearly 90% of the variation in sedimentation rates.

Method of making ferrolectric thin film composites

Abstract: A method of making ferroelectric thin film composites includes the step ofroviding a barium strontium titanate material with an additive magnesia-based and forming a thin film ferroelectric composite using pulsed laser deposition. The method forms a thin film composite having enhanced electronic properties.

Experimental infection of the laboratory rat with the hepatitis E virus.

Abstract: To confirm an earlier report that laboratory rats are susceptible to infection with the hepatitis E virus (HEV), we inoculated 27 Wistar rats intravenously with a suspension of a human stool known to contain infectious HEV. Stool, sera, and various tissues were collected from three rats each on days 0 (preinoculation) and 4, 7, 11, 14, 18, 21, 25, 28, and 35 postinoculation. Stool and sera specimens were examined by reverse transcription-polymerase chain reaction for the presence of HEV genomic sequences. Tissues were examined by light microscopy for detection of histopathological changes and by direct immunofluorescence for detection of HEV antigens. We detected HEV RNA in stools on day 7 in all three animals and in serum intermittently between days 4 and 35. We found HEV antigens in liver, peripheral blood mononuclear cells, spleen, mesenteric lymph nodes, and small intestine. We detected histopathology attributable to the inoculum in liver, spleen, and lymph nodes. The results confirm that HEV can replicate in laboratory rats and suggest new tissue sites for HEV replication.

Vector Competence of Egyptian Mosquitoes for Rift Valley Fever Virus

Abstract: Reintroduction of Rift Valley fever (RVF) into Egypt in 1993 raised concerns about the potential for Egyptian mosquitoes to transmit the virus. We evaluated the ability of Aedes caspius, Culex pipiens, Cx. antennatus, Cx. perexiguus, Cx. poicilipes, and Anopheles pharoensis collected in the Aswan area and Cx. pipiens collected in the Nile Delta to transmit RVF virus. All mosquito species tested were susceptible to RVF virus infection, with An. pharoensis and Ae. caspius being the most sensitive to infection. However, none of 12 An. pharoensis, including 10 with a disseminated infection, transmitted RVF virus by bite. In contrast, nearly all Cx. pipiens (87%, n = 15) and Cx. perexiguus (90%, n = 10) with a disseminated infection transmitted virus. Overall transmission rates for mosquitoes exposed to hamsters with a viremia > or = 10(7) plaque-forming units/ml were Ae. caspius, 20% (n = 5); Cx. pipiens, 7% (n = 102); Cx. antennatus, 7% (n = 30); Cx. perexiguus, 11% (n = 9); and An. pharoensis, 0% (n = 7). Based on abundance, susceptibility to infection, ability to transmit virus, and feeding behavior, Ae. caspius appeared to be the most efficient vector of the Egyptian mosquitoes evaluated. While less susceptible than Ae. caspius, Cx. pipiens, Cx. antennatus, and Cx. perexiguus were also potential vectors during this RVF outbreak in Egypt.

Distance-classifier correlation filters for multiclass target recognition.

Abstract: We describe a correlation-based distance-classifier scheme for the recognition and the classification of multiple classes. The underlying theory uses shift-invariant filters to compute distances between the input image and ideal references under an optimum transformation. The original distance-classifier correlation filter was developed for a two-class problem. We introduce a distance-classifier correlation filter that simultaneously considers multiple classes, and we show that the earlier two-class formulation is a special case of the classifier presented. Initial results are presented to demonstrate the discrimination- and distortion-tolerance capabilities of the proposed filter.