306 research outputs found
Infection of three-spined stickleback Gasterosteus aculeatus (L.) with Corynosoma strumosum in Gomishan Lagoon
To study infection of Three-Spined Stickleback, Gasterosteus aculeatus (14 we sampled 530 specimens of the fish during November 2000 till October 2001 in Gomishan Lagoon, southeast of Caspian Sea. The fish were collected using beach seines with 3mm mesh size. The specimens were transferred to lab fresh or fixed in 10% formalin and examined by standard methods. Numbers of parasites for each male or female were recorded and intensity, frequency and prevalence of the parasite for each month and sex were calculated. Maximum infection occurred in late winter and early spring and the maximum number of parasites was 82, obtained from a female fish in early spring
Panoramic-Based Mandibular Indices and Bone Mineral Density of Femoral Neck and Lumbar Vertebrae in Women
Objective: The aim of this cross-sectional analytic study was to evaluate the diagnostic efficacy of panoramic-based indices of the mandible (Mental Index-MI, Mandibular Cortical Index-MCI and Panoramic Mandibular Index-PMI) and to determine their correlationwith bone mineral density (BMD) of the femoral neck and lumbar vertebrae (L2-L4) in order to assess the possibility of using these parameters as indicators of osteoporosis.Materials and Methods: The mandibular indices of 67 women over 35 years old were measured from panoramic radiographs, and bone densitometry was performed in the femoral neck and lumbar vertebrae (L2-L4), using DXA (Dual Energy X-ray Absorptiometry)technique. The patients were divided into three categories of normal, osteopenic andosteoporotic in each skeletal region. One-way ANOVA and ROC curve analyses were applied.The results were considered statistically significant when the P-value was less than 0.05.Results: Comparing the mean BMD in the femoral neck in women between C1 and C3 subgroups of MCI, a significant difference was detected (P=0.04). The mean PMI in the three skeletal subgroups was not different according to the skeletal region (P>0.05). We found a significant difference in mean MI between normal and osteopenic subgroups in the femoral neck (P=0.042).Conclusion: Using radiomorphometric indices of the mandible (MCI-MI) may be useful in determining the skeletal status of the patients, but is not sufficient for precise evaluation
Wide-field LOFAR-LBA power-spectra analyses: Impact of calibration, polarization leakage and ionosphere
Contamination due to foregrounds (Galactic and Extra-galactic), calibration
errors and ionospheric effects pose major challenges in detection of the cosmic
21 cm signal in various Epoch of Reionization (EoR) experiments. We present the
results of a pilot study of a field centered on 3C196 using LOFAR Low Band
(56-70 MHz) observations, where we quantify various wide field and calibration
effects such as gain errors, polarized foregrounds, and ionospheric effects. We
observe a `pitchfork' structure in the 2D power spectrum of the polarized
intensity in delay-baseline space, which leaks into the modes beyond the
instrumental horizon (EoR/CD window). We show that this structure largely
arises due to strong instrumental polarization leakage () towards
{Cas\,A} ( kJy at 81 MHz, brightest source in northern sky), which is
far away from primary field of view. We measure an extremely small ionospheric
diffractive scale ( m at 60 MHz) towards {Cas\,A}
resembling pure Kolmogorov turbulence compared to
km towards zenith at 150 MHz for typical ionospheric conditions. This is one of
the smallest diffractive scales ever measured at these frequencies. Our work
provides insights in understanding the nature of aforementioned effects and
mitigating them in future Cosmic Dawn observations (e.g. with SKA-low and HERA)
in the same frequency window.Comment: 20 pages, 11 figures, accepted for publication in MNRA
Tuning thermoelectric properties of graphene/boron nitride heterostructures
Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couples states in the graphene, to form mini-bands. In un-doped nanoribbons, the mini bands are symmetrically positioned relative to the Fermi energy and do not enhance thermoelectric performance significantly. In contrast, when the ribbons are doped by electron donating or electron accepting adsorbates, the thermopower S and electronic figure of merit are enhanced and either positive or negative thermopowers can be obtained. In the most favourable case, doping with the electron donor tetrathiafulvalene increases the room-temperature thermopower to -284 μv K(-1) and doping by the electron acceptor tetracyanoethylene increases S to 210 μv K(-1). After including both electron and phonon contributions to the thermal conductance, figures of merit ZT up to of order 0.9 are obtained
Multifunctional semiconductor micro-Hall devices for magnetic, electric, and photo-detection
We report the real-space voltage response of InSb/AlInSb micro-Hall devices to local photo-excitation, electric, and magnetic fields at room temperature using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local electric fields. Experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. The magnetic, photo, and charge sensitivity of a 2 μm wide probe are evaluated at a 10 μA bias current in the Johnson noise limit (valid at measurement frequencies > 10 kHz) to be, respectively, 500 nT/√Hz; 20 pW/√Hz (λ = 635 nm) comparable to commercial photoconductive detectors; and 0.05 e/√Hz comparable to that of single electron transistors. These results demonstrate the remarkably versatile sensing attributes of simple semiconductor micro-Hall devices that can be applied to a host of imaging and sensing applications
Performance comparison of machine learning techniques in sleep scoring based on wavelet features and neighboring component analysis
Introduction: Sleep scoring is an important step in the treatment of sleep disorders. Manual annotation of sleep stages is time-consuming and experience-relevant and, therefore, needs to be done using machine learning techniques. Methods: Sleep-EDF polysomnography was used in this study as a dataset. Support vector machines and artificial neural network performance were compared in sleep scoring using wavelet tree features and neighborhood component analysis. Results: Neighboring component analysis as a combination of linear and non-linear feature selection method had a substantial role in feature dimension reduction. Artificial neural network and support vector machine achieved 90.30 and 89.93 accuracy, respectively. Discussion and Conclusion: Similar to the state of the art performance, the introduced method in the present study achieved an acceptable performance in sleep scoring. Furthermore, its performance can be enhanced using a technique combined with other techniques in feature generation and dimension reduction. It is hoped that, in the future, intelligent techniques can be used in the process of diagnosing and treating sleep disorders. © 2018 Alizadeh Savareh et al
Reliability and reproducibility of spectral and time domain optical coherence tomography images before and after correction for patients with age-related macular degeneration.
PURPOSE: To evaluate the reproducibility and reliability of optical coherence tomography scans obtained using the time domain (TD-OCT) Stratus (TM) OCT, and the Spectral Domain (SD-OCT) Spectralis (TM) and Cirrus (TM) OCT devices before and after manual correction in eyes with either Neovascular (NV-AMD) or Non-Neovascular (NNV-AMD) age-related macular degeneration.
DESIGN: Prospective observational study.
SETTING: University-based retina practice.
PATIENTS: Thirty-six patients (50 eyes) with NV-AMD or NNV-AMD.
PROCEDURE: OCT scans were taken simultaneously using one TD-OCT and two SD-OCT devices.
MAIN OUTCOME MEASURES: Macular thickness measurements were assessed before and after correction of the algorithm by constructing Bland-Altman plots for agreement and calculating intraclass correlation coefficients (ICCs) and coefficients of repeatability (COR) to evaluate intraclass repeatability.
RESULTS: Spectralis had the highest number of images needing manual correction. All machines had high ICCs, with Spectralis having the highest. Also, Bland-Altman plots indicated that there was low agreement between Cirrus™ and Stratus™, Spectralis™ and Stratus™, while there was good agreement between the Cirrus™ and Spectralis™. The CORs were lowest for Spectralis (TM) and similar and higher for Cirrus (TM) and Stratus (TM). Agreement, CORs, and ICCs generally improved after manual correction, but only minimally.
CONCLUSION: Agreement is low between devices, except between both SD-OCT machines. Manual correction tends to improve results
Ordered arrays of gold nanoparticles crosslinked by dithioacetate linkers for molecular devices
The final performance of a molecular electronic device is determined by the chemical structure of the molecular wires used in its assembly. Molecular place-exchange was used to incorporate di-thioacetate terminated molecules into ordered arrays of dodecanethiol capped gold nanoparticles. X-Ray photoelectron spectroscopy confirmed successful molecular replacement. Room-temperature molecular conductance of a statistically large number of devices reveals that conductance is enhanced by up to two orders of magnitude for the di-thioacetate terminated molecules. Density functional theory transport calculations were performed on five different configurations of the di-thioacetate molecules between gold electrodes, and the calculated average conductance values are in good agreement with the experimentally-observed conductance trend. Our findings highlight important cooperative effects of bridging neighboring gold nanoparticles and choice of appropriate molecular wires when designing devices for efficient transport
Breast cancer genetic risk profile is differentially associated with interval and screen-detected breast cancers
Background: Polygenic risk profiles computed from multiple common susceptibility alleles for breast
cancer have been shown to identify women at different levels of breast cancer risk. We
evaluated whether this genetic risk stratification can also be applied to discriminate between
screen-detected and interval cancers, which are usually associated with
clinicopathological and survival differences.
Patients and methods: A 77-SNP polygenic risk score (PRS) was constructed for breast cancer overall and by
estrogen-receptor (ER) status. PRS was inspected as a continuous (per standard deviation
increment) variable in a case-only design. Modification of the PRS by mammographic density
was evaluated by fitting an additional interaction term.
Results: PRS weighted by breast cancer overall estimates was found to be differentially associated
with 1,865 screen-detected and 782 interval cancers in the LIBRO-1 study (age-adjusted
ORperSD [95% confidence interval]=0.91 [0.83-0.99], p=0.023). The association was found to
be more significant for PRS weighted by ER-positive breast cancer estimates (ORperSD=0.90
[0.82-0.98], p=0.011). This result was corroborated by two independent studies (combined
ORperSD=0.87 [0.76-1.00], p=0.058) with no evidence of heterogeneity. When enriched for
“true” interval cancers among nondense breasts, the difference in the association with PRS in
screen-detected and interval cancers became more pronounced (ORperSD=0.74 [0.62-0.89],
p=0.001), with a significant interaction effect between PRS and mammographic density
(pinteraction=0.017).
Conclusion: To our knowledge, this is the first report looking into the genetic differences between screendetected
and interval cancers. It is an affirmation that the two types of breast cancer may have
unique underlying biology.Swedish Research CouncilSwedish Cancer SocietyStockholm County CouncilBreast Cancer Theme Centre Consortium (BRECT)Accepte
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