Dual reflector feed system for hologram-based compact antenna test range

Manufacturing of large computer-generated submillimeter wave holograms with high pattern accuracy has been the main challenge in the development of hologram based compact antenna test ranges (CATRs). Illumination of the hologram with a shaped beam produced by a dual reflector feed system (DRFS) simplifies the hologram manufacturing by eliminating the narrow slots in the hologram pattern. In this paper, the design of a shaped dual reflector feed for a hologram CATR is described. The simulated and measured illumination field amplitude and phase at 310 GHz are presented and compared to the desired hologram illumination. The measured amplitude is within /spl plusmn/0.5 dB from the design objective in the most significant central region of the illuminating beam. Measurement results of the quiet-zone field of a demonstration CATR illuminated by the DRFS are presented and compared to the measured quiet-zone amplitude and phase of a hologram fed directly with a corrugated horn. The quiet-zone diameters of the both holograms are over 0.25 meters and the measured root mean squared (rms) amplitude and phase ripples are below /spl plusmn/0.4 dB and /spl plusmn/5/spl deg/, respectively. Further improvements to the hologram CATR, such as greater tolerance to manufacturing errors, are also discussed.     

Towards an exact many-body solution of jellium clusters

The electronic structure of small spherical jellium clusters is studied by the configuration-interaction method. Convergence as a function of the number of configurations is found to be very slow. The origin of the plasmon resonance in spherical jellium clusters is shown to be due to the nearly exact separation of the center-of-mass motion and the intrinsic motion. Configurations beyond two-particle excitations are found to be essential for the photoabsorption spectrum.     

Analytical specificity and sensitivity of a real-time polymerase chain reaction assay for identification of bovine mastitis pathogens

Intramammary infection (IMI), also known as mastitis, is the most frequently occurring and economically the most important infectious disease in dairy cattle. This study provides a validation of the analytical specificity and sensitivity of a real-time PCR-based assay that identifies 11 major pathogen species or species groups responsible for IMI, and a gene coding for staphylococcal β-lactamase production (penicillin resistance). Altogether, 643 culture isolates originating from clinical bovine mastitis, human, and companion animal samples were analyzed using the assay. The isolates represented 83 different species, groups, or families, and originated from 6 countries in Europe and North America. The analytical specificity and sensitivity of the assay was 100% in bacterial and β-lactamase identification across all isolates originating from bovine mastitis (n = 454). When considering the entire culture collection (including also the isolates originating from human and companion animal samples), 4 Streptococcus pyogenes, 1 Streptococcus salivarius, and 1 Streptococcus sanguis strain of human origin were identified as Streptococcus uberis, and 3 Shigella spp. strains were identified as Escherichia coli, decreasing specificity to 99% in Strep. uberis and to 99.5% in E. coli. These false-positive results were confirmed by sequencing of the 16S rRNA gene. Specificity and sensitivity remained at 100% for all other bacterial targets across the entire culture collection. In conclusion, the real-time PCR assay shows excellent analytical accuracy and holds much promise for use in routine bovine IMI testing programs. This study provides the basis for evaluating the assay's diagnostic performance against the conventional bacterial culture method in clinical field trials using mastitis milk samples.     

Real-time polymerase chain reaction-based identification of bacteria in milk samples from bovine clinical mastitis with no growth in conventional culturing

In more than 30% of milk samples from clinical and subclinical bovine mastitis, bacteria fail to grow even after 48 h of conventional culture. The “no-growth” samples are problematic for mastitis laboratories, veterinarians, and dairy producers. This study provides the first investigation of the bacteriological etiology of such samples, using a real-time PCR-based commercial reagent kit. The assay targets the DNA of the 11 most common bacterial species or groups in mastitis and the staphylococcal blaZ gene (responsible for penicillin resistance) and can identify and quantify bacterial cells even if dead or growth-inhibited. A study was made of 79 mastitic milk samples with no-growth bacteria in conventional culture, originating from cows with clinical mastitis. Of the 79 samples, 34 (43%) were positive for 1 (32 samples) or 2 (2 samples) of the target bacteria. The positive findings included 11 Staphylococcus spp. (staphylococci other than Staphylococcus aureus), 10 Streptococcus uberis, 2 Streptococcus dysgalactiae, 6 Corynebacterium bovis, 3 Staph. aureus, 1 Escherichia coli, 1 Enterococcus, and 1 Arcanobacterium pyogenes. The positive samples contained as many as 10³ to 10⁷ bacterial genome copies per milliliter of milk. This study demonstrates that in nearly half of the clinical mastitis cases in which conventional culture failed to detect bacteria, mastitis pathogens were still present, often in substantial quantities. The clearly elevated N-acetyl-β-d-glucosaminidase activity values of the milk samples, together with clinical signs of the infected cows and quarters, confirmed the diagnosis of clinical mastitis and indicated that real-time, PCR-based bacterial findings are able to reveal bacteriological etiology. We conclude that all common mastitis bacteria can occur in large quantities in clinical mastitis samples that exhibit no growth in conventional culture, and that the real-time PCR assay is a useful tool for bacteriological diagnosis of such milk samples. Low bacterial concentration is commonly speculated to explain the no-growth milk samples. This hypothesis is not supported by the results of the current study.     

The seasonal behavior of interferometric coherence in boreal forest

The capability of SAR interferometry has been previously demonstrated in various applications. In particular, the use of interferometric coherence has shown promising results in forest monitoring, however, mainly in discriminating forested and nonforested areas. The authors have collected ERS-1 and ERS-2 Tandem data from two boreal forest test sites in Finland. The data have been processed into interferometric coherence and intensity images. These images have been used to a) compare the behavior of interferometric coherence and intensity for various land-use and forest classes and b) extensive analysis on the behavior of interferometric coherence in boreal forests as a function of stem volume. Based on the observations and the use of a boreal forest semi-empirical backscattering model, they have developed an empirical model that describes interferometric coherence of boreal forests using backscattering information. The results indicate that coherence is more sensitive to the stem volume than the C-band backscattering intensity. However, the intensity and coherence data contain complementary information and therefore, the use of both data sources is beneficial in the observation of boreal forest     

Book access, shared reading, and audio models: The effects of supporting the literacy learning of linguistically diverse students in school and at home.

Sixteen teachers and their 162 first-grade students participated in this study to explore the impact of book-rich classroom environments and home rereading, with and without an audio model, on reading motivation, comprehension, and fluency. Classrooms with both students who speak English as a second language and native English-speaking students were in 1 of 4 conditions: book-rich classroom environment, book-rich classroom environment and daily rereading of books at home, book-rich classroom environment and daily rereading of books with audiotapes at home, and unmodified reading instruction at school. There was enhanced comprehension for book-rich classrooms, both with and without a home component. Furthermore, home-based rereading increased students' reading motivation and promoted parental involvement. Use of audio models provided particular benefits for students learning to speak English. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serum total renin is elevated in women with polycystic ovarian syndrome

OBJECTIVE: To examine the serum total renin in women with polycystic ovarian syndrome (PCOS) and in controls. SETTING: Outpatient clinic of reproductive endocrinology at Turku University Central Hospital, Turku, Finland. PATIENTS: Forty-four oligomenorrheic women with PCOS (body mass index [BMI] 18.0 to 49.0 kg/m2) and 25 control women with regular menstrual cycles (BMI 18.0 to 53.5 kg/m2). MAIN OUTCOME MEASURES: The concentrations of total renin, LH, FSH, T, androstenedione (A), sex hormone-binding globulin (SHBG), and insulin in serum. RESULTS: The concentration of total renin in serum was higher in PCOS women than in healthy women independently of BMI, age, or serum insulin. The serum total renin measurement discriminated PCOS patients and control women to a similar extent as the previously used hormonal parameters (LH:FSH, T, A, and T:SHBG) as judged by receiver-operating characteristic analysis. Positive correlations were found between the serum total renin level and LH concentration, LH:FSH ratio, T and A levels, and T:SHBG ratio. Analysis of serum total renin in PCOS patients during oligomenorrhea and after menstruation did not reveal any significant changes. CONCLUSIONS: The elevated concentration of serum total renin suggests an enhanced activity of ovarian renin-angiotensin system in PCOS. The determination of serum total renin may provide a novel tool in the diagnostics of PCOS, because its serum level is elevated in PCOS women independently of BMI and serum insulin.     

An averaging mode time-to-amplitude converter with picosecondresolution

A time-to-amplitude converter (TAC) meant to be employed in pulsed time-of-flight (TOF) laser rangefinding and capable of operating at a very high pulse repetition rate (PRR) is described. It is based on a precise time interval between the emitted light pulses and measures the phase difference of the logic-level pulse trains formed by timing pulses derived from the transmitted and received light pulses. The fast part of the TAC is constructed by means of ECL 100 K circuits. Test results indicate that the TAC is well suited for fast, millimeter-level resolution applications, and a full width at half maximum (FWHM) resolution of 1.0 ps is achieved with a 5-MHz pulse repetition rate and 0.1-Hz-10-kHz measurement bandwidth     

Methods of calculating radial boundary conditions for flux trap control assemblies

Some methods of calculating a two- or four-group albedo matrix for the control assemblies of VV'ER-440 reactors are discussed. All of these methods use the S_N program DTF-IV to calculate partial neutron currents, but the group constants for the DTF-IV calculations were obtained by different methods. The influence of the boron steel absorber on the thermalization cross section of the water in the control assembly turned out to affect the albedo matrix significantly. The control assembly itself does not, however, have any significant effect on the group constants of adjacent fuel assemblies.Published in Atomnaya Energiya, Vol. 52, No. 1, pp. 39–44, January, 1982.     

Associations between human aldosterone synthase (CYP11B2) gene polymorphisms and left ventricular size, mass, and function

OBJECTIVE: The effectiveness of CLP (Consultation and liaison psychiatry) interventions in a general hospital is difficult to evaluate; parameters potentially determinant as to effectiveness are numerous. Effectiveness evaluations are almost exclusively restricted to the duration of hospitalization. Since CLP may and often should be manifest beyond discharge, we intended to determine the agreement between our proposition and its execution as a measure of effectiveness. METHOD: We based our analyses principally on the general practitioner's appreciation of the CLP impact, a measure of effectiveness at distance from the consultation by a judge not directly involved in the consulting process. This qualitative assessment is based on a population of 50 patients. RESULTS: Our results suggest that agreement between our proposal and its complete execution is good concerning medication (90%) and referral rate after the hospitalization (85%), average as to liaison suggestions (65%) and clearly weak as to propositions regarding further investigations (< 30%). CONCLUSION: CLP proposals must be as close as possible to the in-patient physician's preoccupations to enhance the probability that they be executed. The concordance as to the proposal and its execution as well as the CLP impact estimation need be evaluated at distance. This evaluation must imply the general practitioner's assessment.