Mean Detection Time Research Articles

Highway traffic incident detection based on BPNN

Because traffic incident is the main cause of traffic congestion in Highway, traffic incident detection plays an important role in ITS. Based on the professional software VISSIM, we performed an experiment on incident caused by traffic jam to obtain the original simulated data. We offered a way to deal and analyse the traffic prameters, then an updated automatic traffic incident detection method was proposed based on BP neural network. Simulation result shows that the new method has many advantages such as higher detection rate, lower false alarm rate and shorter mean detection time.

Performance and Complexity Evaluation of OTR-UWB Receiver

This article presents a new transmitted reference UWB receiver, which utilizes the orthogonal property of even and odd order derivatives of Gaussian pulses in neighboring chips for synchronization. This system, referred to as orthogonal TR-UWB (OTR-UWB), employs only a single spreading code, which results in much lower mean detection time compared to DS-UWB systems. The hardware complexity for OTR-UWB receiver is significantly reduced against conventional TR-UWB systems. In addition, simulation results show that BER performance is improved, while the new system is capable of supporting higher data rates. Also, this article presents the FPGA implementation of OTR-UWB, with a bit-rate of 25Mb/s without using equalizer. In addition, we present the DSP algorithm of baseband. Hardware of this system is implemented on two different FPGAs from ALTERA and XILINX, CycloneII (EP2C35F672C6) and Spartan 3 (3s4000fg676-5). Gate estimation and power analysis are performed by Quartus II 7.2 (ALTERA) and ISE 8.1 (XILINX) softwares.

Baseband implementation of OTR-UWB receiver using FPGA

This paper presents a new transmitted reference ultra-wideband receiver, which utilizes the orthogonal property of even and odd order derivatives of Gaussian pulses in neighboring chips for synchronization. This system, referred to as orthogonal TR-UWB (OTR-UWB), employs only a single spreading code, which results in much lower mean detection time compared to DS-UWB systems since smaller search space is involved for coarse acquisition. The hardware complexity for OTR-UWB receiver is significantly reduced against conventional TR-UWB systems. In addition, simulation results show that bit error rate (BER) performance is improved, while the new system is capable of supporting higher data rates. Also, this paper presents a technique for implementing low rate OTR-UWB system in FPGA by combining pipeline scheduling, parallel component, and module selection. The system has been implemented on two FPGA platforms from ALTERA and XILINX, CycloneII (EP2C35F672C6) and Spartan 3 (3s4000fg676-5)with a bit-rate of 25Mb/s without using equalizer. It incorporates 4-bit of resolution with 8GHz frequency sampling rate for analog to digital conversion realized by parallel low frequencyADC blocks. Gate estimation and power analysis are performed by Quartus II 7.1 (ALTERA) and ISE 8.1 (XILINX) softwares.

Analytic Model for Aircraft Survivability Assessmentof a One-on-one Engagement

Aircraft survivability assessment is one of the most important steps of the aircraft survivability project. Many models were developed to assess one-on-one engagement aircraft survivability; however, most of them belong in the simulation category. Based on the theory of stochastic duel, this paper constructs an analytic model for engagement-level aircraft survivability assessment. The analytic model explicitly represents the encounter process between the aircraft and the weapon system, such as target detection, acquisition and firing, and reloading and firing. The general solution of aircraft survival probability is obtained in quadrature form and the explicit expression is derived from a particular detection-time distribution and a firing-time distribution. According to this model, not only can the aircraft survival probability be calculated, but the survivability contour maps can also be easily plotted with the mean time of detection, the single-shot kill probability, and other parameters. The numerical examples and analysis of the results show that the model is reasonable and effective.

Delayed insertion of blood culture bottles into automated continuously monitoring blood culture systems increases the time from blood sample collection to the detection of microorganisms in bacteremic patients

This study examined the effects on patients with bacteremia of delaying the insertion of a blood culture bottle into an automated, continuously monitoring blood culture system. We investigated the time taken from the collection of blood samples (collection) to the insertion of blood culture bottles inoculated with blood samples into the instrument (insertion), and compared the mean detection time from collection to a positive signal from the instrument with the time between collection and insertion. The study was conducted from January 2003 to December 2004 at Kyoto University Hospital. Insertion into the system on the day of blood sample collection was defined as same-day insertion, and insertion on a different day to collection was defined as delayed insertion. The 7394 aerobic and anaerobic blood culture bottle sets obtained during the study period included 4361 sets with same-day insertion and 3033 sets with delayed insertion. For same-day insertion, 458 microorganisms were isolated from 432 positive sets in which at least one blood culture bottle was positive. For delayed insertion, 405 microorganisms were isolated from 379 positive sets in which at least one blood culture bottle was positive. The mean detection time for all microorganisms was significantly earlier for same-day insertion than for delayed insertion (28.3 h vs. 45.0 h, respectively, P < 0.0001). Delays from collection to insertion affect the time from collection to the detection of microorganisms.

Comparative Evaluation of Three Culture Methods for the Isolation of Mycobacteria from Clinical Samples

We assessed the capacity of two liquid-medium culture methods with automated incubation and reading systems (MB/BacT ALERT 3D System and BACTEC MGIT 960 System) and one solid-medium culture method (Löwenstein- Jensen) to detect mycobacteria in different types of clinical samples. Out of 1,770 cultured clinical samples (1,519 of respiratory origin and 251 of nonrespiratory origin), mycobacteria were isolated in 156 samples (135 M. tuberculosis complex, 8 M. chelonae, 6 M. kansasii, 4 M. fortuitum, 2 M. gordonae, and 1 M. marinum) by at least one of the methods used. The BACTEC MGIT 960 System proved to be the most sensitive method (86.5%), especially in the detection of M. tuberculosis complex (89.1%). However, Löwenstein- Jensen culture was the most sensitive (76.2%) to detect nontuberculous mycobacteria. The BACTEC MGIT 960 System showed the lowest mean detection time for mycobacterial growth (15.3 days), significantly shorter than the other two methods. Highest sensitivity (95.5%) and specificity (99.6%) values were obtained using the BACTEC MGIT 960 System with the Löwenstein-Jensen culture method, which was also the only combination capable of detecting 100% of the nontuberculous mycobacteria.

Comparison of MPCAV, ARPCA, and BDPCA fault detection performance in a fed-batch penicillin fermentation process

A close monitoring of batch processes in the chemical and biochemical industry is required to achieve a satisfactory product quality at the end of a batch run. To deal with the inherent auto- and cross-correlation within batch process data, specific techniques, based on Principal Component Analysis (PCA) were developed for monitoring and fault detection purposes. In this paper, the fault detection performances of two such techniques, AutoRegressive PCA [ARPCA; Choi et al., 2008. Dynamic model-based batch process monitoring. Chemical Engineering Science 63:622–636] and Batch Dynamic PCA [BDPCA; Chen and Liu, 2002. On-line batch process monitoring using dynamic PCA and dynamic PLS models. Chemical Engineering Science, 57:63–75], and a standard Multi-way PCA technique with Variable-wise unfolding (MPCAV) are compared. As a case study, a biochemical fed-batch process for penicillin fermentation is selected. From the extensive simulation results, it is clear that both ARPCA and BDPCA outperform the MPCAV procedure, with a significant reduction in fault detection times and, as a consequence, higher fault detection rates. The difference in performance between ARPCA and BDPCA, however, is very small. While ARPCA shows a smaller mean detection time over all test batches, the fault detection time for BDPCA is still smaller in a lot of individual batches. Therefore, it is concluded that, for the test cases presented in this paper, the ARPCA en BDPCA fault detection techniques show a similar performance.

Value of anaerobic culture in bacterial surveillance program for platelet concentrates

Short-term aerobic bacterial culture (STABC) has been used routinely in Hong Kong since 1998 to reduce bacterial contamination in platelet concentrates (PCs) with good results. With more countries implementing routine aerobic and anaerobic cultures of PCs, a prospective study was conducted to determine the value of anaerobic culture to STABC. PC tested by STABC was used as control. Twenty milliliters of the PC selected for this study was aliquoted and pooled for 7 days aerobic and anaerobic culture. If the initial culture was positive, samples retrieved from the original PC and their associated components were cultured for confirmation and microbiologic identification. A total of 10,035 PC units (2007 pools) were tested. The confirmed positive rates by aerobic and anaerobic cultures per pool were 3 (0.15%) and 13 (0.65%), respectively, which was equivalent to an increased yield from 0.03 to 0.13 percent of PC if anaerobic culture was added. Of the 10 bacteria detected by anaerobic culture only, 9 were found to be Propionibacterium acnes and the remaining one Peptostreptococcus sp. Their mean detection time from inoculation was 92.16 hours (range, 50.4-124.8 hr). Addition of anaerobic culture to our routine STABC would significantly increase the detection rate of bacterial contaminated PC. However, since only slow-growing bacteria were detected, and because their clinical significance was uncertain, it is concluded that there was no clear justification to introduce anaerobic culture locally if 5-day shelf life for PCs was to be maintained.

Distribution, Optimum Detection Time and Antimicrobial Susceptibility Rates of the Microorganisms Isolated from Blood Cultures over a 4-Year Time Period in a Turkish University Hospital and a Review of the International Literature

This study retrospectively examined 8986 blood cultures from patients over a 4-year time period in an eastern Turkish university hospital to determine the detection times and distribution of isolated microorganisms using the automated BACTEC 9050 and BACTEC 9120 systems. A total of 1914 (21.3%) blood cultures contained pathogenic microorganisms and 252 (2.8%) positive cultures were considered contaminated. Of all the cultures, 18 (0.2%) were false positives and 224 (2.5%) were false negatives. In cultures containing pathogenic microorganisms, Gram-positive and Gram-negative bacterial isolation rates were 436 (22.8%) and 1440 (75.2%), respectively, and yeasts (all Candida sp.) were found in 38 (2.0%) cultures. Coagulase-negative staphylococci occurred in 936 (48.9%) cultures and Staphylococcus aureus occurred in 302 (15.8%) cultures. The mean detection time for all of the pathogens was 21 h and Brucella spp were isolated within 10 days. This study helps in understanding the epidemiology of the region and in providing positive therapeutic approaches. A review of the international literature helps to place this understanding into a global context.

Effective Crypsis and Its Maintenance by Immobility in Craugastor Frogs

Prey that are cryptic when at rest should limit movement to avoid disrupting crypsis. We studied effectiveness of crypsis and degree of reliance on immobility versus escape by Craugastor frogs approached by a predator. We studied detectability of C. fitzingeri resting in a 2 m diameter circle of leaf litter using four human observers. Nearly 40% of frogs were not detected within 60 s, and mean detection time was more than 30 s despite a small search area. Given a much lower density in natural habitats, it is likely that these frogs are rarely detected visually without area-concentrated search, except perhaps by predators sensitive to wavelengths not detected by human beings. When approached by a human, over 90% of individuals belonging to five species of Craugastor remained immobile until the predator reached them. Only C. noblei fled, and this species fled more frequently than the others at higher approach speed. Approach speed did not affect probability of jumping or distance jumped. Distance jumped varied among species, but was unrelated to body length except for C. mimus during fast approaches. Extreme reliance on crypsis reinforced by immobility suggests that crypsis is so effective in these frogs that survivorship may be higher for individuals that do not attempt to escape. The increased probability of being detected and attacked upon moving combined with limited escape capacity presumably raises the probability of being captured for frogs that jump. The importance of crypsis is emphasized by observations that almost all frogs that jumped reestablished crypsis after a single jump by becoming immobile, and some burrowed into leaf litter upon landing, concealing the head and part of the body.

Comparative evaluation of FASTPlaque assay with PCR and other conventional in vitro diagnostic methods for the early detection of pulmonary tuberculosis

Rapid and accurate diagnosis of symptomatic patients of pulmonary tuberculosis (TB) is highly desirable to minimize the spread of the disease in the society. We, therefore, compared the usefulness of various conventional diagnostic methods, the in-house polymerase chain reaction (PCR), and the FASTPlaque assay in this study. Laboratory data of 150 patients with clinical diagnosis of pulmonary TB and 50 controls were included in this study. The sputa from all these 200 individuals were subjected to acid-fast staining, culture on Lowenstein-Jensen (L-J) slants, automated BACTEC-MGIT-960 culture methods, and a mycobacteriophage assay. A mycobacterium genus and Mycobacterium tuberculosis species-specific PCRs were also done and samples positive on both PCRs were considered as standard for comparison. Of the 5 in vitro diagnostic tests, PCR method was found to be the most rapid, sensitive, and specific, detecting all the 150 cases of pulmonary TB without any false-positive and negative result. In comparison with PCR the sensitivity of MGIT-960 was 90%, followed by FASTPlaque assay (76.7%), L-J culture method (73.3%), and microscopy (60%). The mean detection time for smear-positive and smear-negative samples was 12.5 and 14 days in MGIT-960 and 18 and 25 days for L-J method, respectively. The FASTPlaque failed to detect mycobacteria from the paucibacillary samples. The contamination rates for MGIT-960, L-J, and FASTPlaque assays were 4, 8 and 10%, respectively. The best correlation with mycobacterial load in the specimen was observed in BACTEC-MGIT-960 showing 66.6% detection rate in paucibacillary, 83.3% in 1+ samples, and 100% in 2+ and 3+ samples. Out of the 150 patients, 140 (93.3%) could be diagnosed by one or more nonmolecular methods. Therefore, it could be concluded that combination of three or more in vitro diagnostic methods will have acceptable detection level.

Abstract 75: Electronic Integrated Monitoring of Medical Emergency Team Calls to a Step Down Unit

Purpose: Early discharge from intensive care units (ICU) to lower acuity monitoring units (step-down units or SDU) is increasing to improve care throughput. However, the ability of minimally invasive monitoring via electronic integrated monitoring systems (IMS) in SDUs to identify cardiopulmonary deterioration in order to activate Medical Emergency Team (MET) response is unknown. We evaluated the ability of an IMS index value to detect clinically significant events which might trigger activation of the MET earlier than called. Methods: Patients were monitored on a 24 bed trauma SDU according to prevailing policy and bedside decision making. An IMS (BioSign TM ) was inserted into the monitoring system and IMS data were collected in a blinded fashion for 8 weeks from all patients. The IMS uses 4 parameters (heart rate [HR], respiratory rate [RR], blood pressure [BP], peripheral oxygen saturation [SpO 2 ]) to develop a single neural networked signal known as the BioSign Index (BSI). Data were analyzed for patient deterioration according to both BSI trigger value and local MET criteria (DeVita, Qual Safety Health Care 2004). Results: Data from 333 patient admissions were evaluated reflecting 18,692 hours of continuous monitoring. SpO 2 monitoring data were absent in 38.5% of monitored hours, despite being mandatory. Most patients were stable throughout their SDU stay. MET activation occurred on 10 occasions (4 respiratory cause [2 SpO 2 , 2 SpO 2 +RR], 2 cardiac (BP), 1 mixed respiratory + cardiac, and 3 other (1 chest pain, 2 acute mental status change). All 7 MET events of respiratory and/or cardiac cause were detected by BSI in advance (mean advanced detection time prior to MET activation was 6.33 hours). Cardiopulmonary deterioration was generally characterized by progressive increases in BSI over time, not step increases. Conclusion : In this population, cardiopulmonary deterioration requiring MET activation was uncommon but always preceded by IMS index elevations which would have alerted the nursing staff in advance. Continuous monitoring of physiological variables may be augmented by integrating information from multiple parameters to create a new variable. The new index parameter may detect patient deterioration earlier than single parameter monitoring.

Rapid diagnosis of experimental meningitis by bacterial heat production in cerebrospinal fluid

BackgroundCalorimetry is a nonspecific technique which allows direct measurement of heat generated by biological processes in the living cell. We evaluated the potential of calorimetry for rapid detection of bacterial growth in cerebrospinal fluid (CSF) in a rat model of bacterial meningitis.MethodsInfant rats were infected on postnatal day 11 by direct intracisternal injection with either Streptococcus pneumoniae, Neisseria meningitidis or Listeria monocytogenes. Control animals were injected with sterile saline or heat-inactivated S. pneumoniae. CSF was obtained at 18 hours after infection for quantitative cultures and heat flow measurement. For calorimetry, 10 μl and 1 μl CSF were inoculated in calorimetry ampoules containing 3 ml trypticase soy broth (TSB).ResultsThe mean bacterial titer (± SD) in CSF was 1.5 ± 0.6 × 108 for S. pneumoniae, 1.3 ± 0.3 × 106 for N. meningitidis and 3.5 ± 2.2 × 104 for L. monocytogenes. Calorimetric detection time was defined as the time until heat flow signal exceeded 10 μW. Heat signal was detected in 10-μl CSF samples from all infected animals with a mean (± SD) detection time of 1.5 ± 0.2 hours for S. pneumoniae, 3.9 ± 0.7 hours for N. meningitidis and 9.1 ± 0.5 hours for L. monocytogenes. CSF samples from non-infected animals generated no increasing heat flow (<10 μW). The total heat was the highest in S. pneumoniae ranging from 6.7 to 7.5 Joules, followed by L. monocytogenes (5.6 to 6.1 Joules) and N. meningitidis (3.5 to 4.4 Joules). The lowest detectable bacterial titer by calorimetry was 2 cfu for S. pneumoniae, 4 cfu for N. meningitidis and 7 cfu for L. monocytogenes.ConclusionBy means of calorimetry, detection times of <4 hours for S. pneumoniae and N. meningitidis and <10 hours for Listeria monocytogenes using as little as 10 μl CSF were achieved. Calorimetry is a new diagnostic method allowing rapid and accurate diagnosis of bacterial meningitis from a small volume of CSF.

Detection probability and detection time using clutter metrics

We modified the structure similarity index, which is extensively used for image quality assessment, to be clutter metrics and call them target structure similarity measures (TSSIM). Two methods for calculating the TSSIM metrics were suggested. In this paper, via different mathematical formulas, the metrics are used to predict detection probabilities and detection times. The degrees of correlation between various clutter metrics and both the target detection probabilities and the mean detection times, which are obtained from the Search_2 dataset, are presented. Based on these data, comparisons between TSSIMs and three other typical clutter metrics are demonstrated. Experiment results show the TSSIMrms measure generates much better predictive capabilities for both the experimental detection probabilities and the mean detection times than other clutter measures being compared.

Intraoperative fluoroscopy vs. intraoperative laparoscopic ultrasonography for early colorectal cancer localization in laparoscopic surgery

In colorectal cancer (CRC) surgery, precise tumor localization is important for oncologically correct surgery and adequate tumor and lymph node resection margins. During laparoscopic surgery it is difficult to localize early CRC. The aim of this study was to compare the usefulness of two tumor localization techniques; intraoperative fluoroscopy and intraoperative laparoscopic ultrasonography. Seventeen patients with CRC necessitating preoperative marking were alternately allocated to either the fluoroscopy (F) group (n = 8) or the laparoscopic ultrasonography (LU) group (n = 9). A three-step technique was used. At first lesions were localized preoperatively by metallic clips that were colonoscopically applied proximally and distally to the tumor site. Second, computed tomography (CT) colonography was taken to obtain preoperative staging. The location of the metallic clips was confirmed by CT colonography, preoperatively. Third, in the F group, intraoperative fluoroscopy was performed to localize the applied clips. In the LU group, the applied clips were detected from the serosal aspect of the colon using intraoperative laparoscopic ultrasonography. In all patients, colonoscopic metallic clips were successfully applied and preoperative CT colonography correctly detected the location of the tumor. Marking sites were detected precisely using intraoperative fluoroscopy or intraoperative laparoscopic ultrasonography in all cases, without complications. The mean detection time was 15.8 minutes in the F group and 7.0 minutes in the LU group (p = 0.005). In the LU group, two cases were technically difficult because of interruption of the ultrasound by intestinal air. Both intraoperative fluoroscopy and intraoperative laparoscopic ultrasonography are safe and accurate techniques for intraoperative localization of early CRC. With regard to detection time, intraoperative laparoscopic ultrasonography is superior to intraoperative fluoroscopy. However, when there is a massive amount of intestinal air, intraoperative laparoscopic ultrasonography is cumbersome in localizing the lesion. Computed tomography colonography is useful for preoperative tumor localization and might be effective for shortening detection time during surgery.

The perception of passive motion in Parkinson's disease

The perception of limb motion is a kinaesthetic property that is essential for voluntary motor control. This study examined the ability of patients with Parkinson's disease (PD) to detect the velocity of a passively moved limb. Eight patients with mild to moderate PD and eight age-matched healthy controls participated. They placed their forearm on a padded splint of a passive motion apparatus, which horizontally extended or flexed the elbow joint at velocities between 1.65 and 0.075 degrees /s (in steps of 0.15 degrees /s). Passive movement persisted until subjects detected arm motion and pressed a trigger held in the hand of their non-tested arm. Time until detection and associated arm displacement were recorded and subsequently adjusted for each subject's reaction time. We found that PD patients needed significantly larger limb displacements before they could judge the presence of passive motion. With decreasing passive motion velocity the detection time increased exponentially in both groups. Yet, the mean detection times of the PD group were 92-166% higher than in the control group for each of the 12 tested velocity conditions. Five of the eight patients were on Parkinsonian medication when tested. Yet, the degree of impairment in the PD group did not correlate significantly with the patients' levodopa equivalent dosage. Our results demonstrate that PD patients were impaired in the detection of passive forearm movements. This study complements a growing body of evidence indicating that various aspects of kinaesthesis (position sense, weight perception, passive motion sense) are affected even at early stages of PD. The impaired processing of proprioceptive signals likely contributes to motor symptoms in PD.

Intraoperative localization of early-stage upper gastrointestinal tumors using a magnetic marking clip–detecting system

Intraoperative tumor localization often is difficult during laparoscopic surgery for early-stage upper gastrointestinal tumors. This study enrolled 15 patients undergoing laparoscopic gastrectomy. A magnetic marking clip-detecting system was used to apply a marking clip to the tumor site during preoperative gastroscopy, and to detect a marking magnetic body. In a basic ex vivo study, the mean permeance rate on the gastric wall serosal surface was 0.97 +/- 0.01. Magnetic flux densities required for exploration were 52.6 mT on the gastric wall serosal surface and 312.4 mT 10 mm away from the surface. In a clinical study, the mean distance between the detected tumor site and the clip along the longitudinal axis was 8.3 +/- 3.2 mm. The mean detection time was 5.7 +/- 2.3 min. The magnetic marking clip-detecting system may be useful for tumor site detection during laparoscopic gastrectomy.

Evaluation of anti-A60 antigen IgG enzyme-linked immunosorbent assay for serodiagnosis of pulmonary tuberculosis.

BACKGROUND:Problems in the diagnosis of tuberculosis using smear and culture techniques have necessitated the exploration of the utility of serodiagnosis to support clinical suspicion of tuberculosis. Anti-A60 antigen IgG enzyme-linked immunosorbent assay (ELISA) was evaluated as a tool for the diagnosis of active pulmonary tuberculosis.MATERIALS AND METHODS:ELISA was used for the detection of immunoglobulin G (IgG) against A60 antigen in parallel with other familiar diagnostic methods in 70 patients with pulmonary tuberculosis (Group_I) along with 70 controls showing evidence of latent tuberculosis infection (Group II).RESULTS:ELISA results were positive in 63 (90%) patients in Group_I compared to three (4%) controls in Group_II. Group_I patients had significantly higher titers of IgG (mean = 750.79 ± 115.87 U/ml against the A60 antigen as compared to Group II controls (mean = 206.67 ± 20.81 U/ml (P < 0.0001). The overall sensitivity and specificity obtained using ELISA were 90 and 95.7% respectively in active pulmonary tuberculosis. Ziehl-Nielsen (Z-N) stains for acid-fast bacilli were positive in 60 (85.7%) patients. In 48 (68.6%) patients, M. tuberculosis grew on both Lowenstein-Jensen (L-J) medium and BACTEC MGIT 960 liquid medium with mean detection times of 45 and 8 days respectively. Tuberculin skin test was positive in 38 (54.3%) patients. Chest X-ray results were consistent with the diagnosis of pulmonary tuberculosis in 53 (75.7%) patients.CONCLUSION:Anti-A60 IgG ELISA results were significantly positive and associated with elevated antibody titers in pulmonary tuberculosis as compared to latent mycobacterium infection. The high diagnostic performance of the test makes it a useful, simple and rapid supporting tool to validate clinical suspicion of active pulmonary disease.

In vitro evaluation of three bacterial culture systems for the recovery of Escherichia coli from equine blood

To evaluate the effectiveness of a commercial conventional blood culture system (BCS), a commercial resin-containing BCS, and a commercial lysis-centrifugation-based BCS for the recovery of Escherichia coli from equine blood samples inoculated with that organism. Samples of blood obtained from a clinically normal horse that were inoculated with E coli. Blood samples were aseptically collected and inoculated with an E coli specimen (50 CFUs/mL) that had been previously isolated from a foal with sepsis. Subsequently, samples were spiked with gentamicin at a concentration of 30 mug/mL, and 10 mL of each mixture was inoculated into 1 bottle or tube of each BCS. Samples were processed and incubated according to the manufacturer's guidelines and inoculated onto 5% sheep blood agar plates. Plated samples were examined macroscopically at regular intervals for as long as 72 hours. Detection of E coli and time to detection were recorded for each medium. Detection frequency of E coli was significantly greater by use of the resin-containing BCS (14/23 bottles) than that achieved by use of the conventional BCS (7/23 bottles) or the lysis-centrifugation-based BCS (0/10 tubes). Mean detection time (6 hours after plating) did not differ between the BCS with conventional medium and the BCS with resincontaining medium. Results suggest that a BCS with resin-containing medium may provide clinical benefit in the successful recovery of E coli from the blood of foals with sepsis that have been previously administered gentamicin.

Ultra-wideband signal acquisition with hybrid DS-TH spreading

The usage of long spreading sequences and the fine timing resolution result in a large search space during acquisition in ultra-wideband (UWB) systems. This paper presents a two-stage signal acquisition scheme for UWB systems employing a hybrid signaling format involving direct sequence (DS) spreading and time hopping (TH), which significantly reduces the search space. The resulting acquisition system consists of two stages, one each for the acquisition of the TH and DS sequences. The dense multipath channel typical of UWB systems implies that there can exist more than one phase to which the receiver can lock on and achieve satisfactory demodulation performance subsequent to acquisition. We define the set of such phases as the hit set. The hybrid signaling format coupled with the multi-phase hit set help significantly improve the acquisition performance of the UWB system. The performance of the proposed acquisition system, measured in terms of the mean detection time, is evaluated analytically and supported by computer simulation