931 research outputs found
Optimization of 3D texture analysis of MR cartilage images for prediction of knee osteoarthritis
Abstract. This thesis attempted to optimize a novel GLCM-based 3D Texture Analysis software in terms of its input parameters in order to maximize the early prediction of knee osteoarthritis from 3D DESS MR images. 20 subjects (10 control subjects; 10 progressor subjects) containing image data from baseline and from a 36-month-follow-up were extracted from the Osteoarthritis Initiative database and used as the study dataset. Multiple sets of 3D Texture Analysis were conducted incorporating 22 static and dynamic grey level quantization schemes, 6 bin quantization schemes and 4 offset settings. Cliffâs delta was calculated to measure the effect size between the patient cohorts. Multilayer perceptron, NaĂŻve Bayes and Support Vector Machines were implemented to classify the patients into their respective cohorts and estimate the robustness of the 3D Texture Analysis outputs. The predictions were done using only the baseline data, where all patients showed no signs of osteoarthritis. Maximum achieved robustness was 87%. The 3D Texture Analysis was found to have a high potential for the early prediction of knee osteoarthritis based on the GLCM features and the results outlined the importance of the softwareâs input parameters
Effects of Fish Populations on Pacific Loon (Gavia pacifica) and Yellow-billed Loon (G. adamsii) Lake Occupancy and Chick Production in Northern Alaska
Predator populations are vulnerable to changes in prey distribution or availability. With warming temperatures, lake ecosystems in the Arctic are predicted to change in terms of hydrologic flow, water levels, and connectivity with other lakes. We surveyed lakes in northern Alaska to understand how shifts in the distribution or availability of fish may affect the occupancy and breeding success of Pacific (Gavia pacifica) and Yellow-billed Loons (G. adamsii). We then modeled the influence of the presence and abundance of five fish species and the physical characteristics of lakes (e.g., hydrologic connectivity) on loon lake occupancy and chick production. The presence of Alaska blackfish (Dallia pectoralis) had a positive influence on Pacific Loon occupancy and chick production, which suggests that small-bodied fish species provide important prey for loon chicks. No characteristics of fish species abundance affected Yellow-billed Loon lake occupancy. Instead, Yellow-billed Loon occupancy was influenced by the physical characteristics of lakes that contribute to persistent fish populations, such as the size of the lake and the proportion of the lake that remained unfrozen over winter. Neither of these variables, however, influenced chick production. The probability of an unoccupied territory becoming occupied in a subsequent year by Yellow-billed Loons was low, and no loon chicks were successfully raised in territories that were previously unoccupied. In contrast, unoccupied territories had a much higher probability of becoming occupied by Pacific Loons, which suggests that Yellow-billed Loons have strict habitat requirements and suitable breeding lakes may be limited. Territories that were occupied had high probabilities of remaining occupied for both loon species.
Les populations de prĂ©dateurs sont vulnĂ©rables aux changements de rĂ©partition ou de disponibilitĂ© des proies. En raison du rĂ©chauffement des tempĂ©ratures, on prĂ©voit que les Ă©cosystĂšmes lacustres de lâArctique changeront pour ce qui est du rĂ©gime hydrologique, des niveaux dâeau et de la connectivitĂ© avec dâautres lacs. Nous avons examinĂ© des lacs du nord de lâAlaska pour comprendre comment les changements en matiĂšre de rĂ©partition ou de disponibilitĂ© des poissons peuvent avoir des incidences sur le taux dâoccupation et sur le succĂšs de reproduction du huart du Pacifique (Gavia pacifica) et du huart Ă bec blanc (G. adamsii). Ensuite, nous avons modĂ©lisĂ© lâinfluence de la prĂ©sence et de lâabondance de cinq espĂšces de poissons de mĂȘme que les caractĂ©ristiques physiques de lacs (comme la connectivitĂ© hydrologique) par rapport au taux dâoccupation lacustre des huarts et Ă la production dâoisillons. La prĂ©sence du dallia (Dallia pectoralis) avait une influence positive sur lâoccupation et la production dâoisillons chez le huart du Pacifique, ce qui suggĂšre que les espĂšces de poissons au petit corps constituent une proie importante pour les oisillons. Aucune caractĂ©ristique de lâabondance des espĂšces de poissons nâa eu dâinfluence sur lâoccupation lacustre du huart Ă bec blanc. Lâoccupation du huart Ă bec blanc a plutĂŽt Ă©tĂ© influencĂ©e par les caractĂ©ristiques physiques des lacs qui contribuent aux populations de poissons persistantes, comme la taille du lac et la proportion du lac qui ne gelait pas en hiver. Toutefois, aucune de ces variables nâa exercĂ© dâinfluence sur la production dâoisillons. La probabilitĂ© quâun territoire inoccupĂ© devienne occupĂ© par le huart au bec blanc au cours dâune annĂ©e subsĂ©quente Ă©tait faible, et aucun oisillon huart nâa Ă©tĂ© Ă©levĂ© avec succĂšs dans des territoires dâoisillons anciennement inoccupĂ©s. En revanche, les territoires inoccupĂ©s avaient une beaucoup plus grande probabilitĂ© de devenir occupĂ©s par les huarts du Pacifique, ce qui suggĂšre que les huarts Ă bec blanc ont des exigences strictes en matiĂšre dâhabitat et que le nombre de lacs convenant Ă la reproduction risque dâĂȘtre limitĂ©. Les territoires qui Ă©taient occupĂ©s avaient de fortes probabilitĂ©s de rester occupĂ©s par les deux espĂšces de huarts
VIRUSES OF SOME GARLIC ECOTYPES IN CROATIA
Recent, there is increasing demand for autochthonous ecotypes of garlic (Allium sativum L.) in Croatia. Many local ecotypes of garlic are developed due to specific environmental conditions and producer's selection. However, the average yield of garlic is not in the European average range, since the classical vegetative propagation from cloves usually results with virus infections that cause significant yield reduction. Viruses are considered significant garlicâs pathogens. The research was set up to determine infection rate in plant material of different garlic ecotypes grown from cloves in different regions. Plants were collected from commercial fields in Zadar County (coastal part of Croatia) and Vukovar-Srijem County (eastern Croatia) and were tested by enzyme-linked immunosorbent assay (ELISA) on the presence of three viruses: Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV) and Garlic common latent virus (GCLV). As a potential source ofantigen leaf tissue was used and tests were conducted according to manufacturerâs instructions (Bioreba AG, Switzerland). In plants from Zadar County dominant was OYDV, followed by GCLV and LYSV. All tested plants originating from Vukovar-Srijem County were infected with three tested viruses. Out of 316 analyzed plants only 4 (1.3%) showed to be free from viruses included in survey. Plants infected with OYDV showed symptoms of leaf yellowing and reduced growth, while those infected with LYSV expressed yellow stripes. Symptoms were most evident at the beginning of vegetation. Due to high infection rate, deteriorated sanitary status, and increased interest in use and production of local garlic ecotypes, work on sanitary selection will be important part of revitalization program
YBa2Cu3O7âÎŽ films: Calculation of the thermal conductivity and phonon meanâfree path
We estimate the phonon meanâfree path (mfp) in YBa2Cu3O7âÎŽ by performing a theoretical fitting procedure on bulk singleâcrystal data. This analysis indicates that the mfps of the phonons that are most responsible for the transport of heat are much longer than would be predicted from kinetic theory. These values are incorporated into a recently proposed treatment of the size effect to provide an estimate of the thermal conductivity of YBa2Cu3O7âÎŽ films.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70503/2/JAPIAU-72-10-4788-1.pd
How should we interpret the two transport relaxation times in the cuprates ?
We observe that the appearance of two transport relaxation times in the
various transport coefficients of cuprate metals may be understood in terms of
scattering processes that discriminate between currents that are even, or odd
under the charge conjugation operator. We develop a transport equation that
illustrates these ideas and discuss its experimental and theoretical
consequences.Comment: 19 pages, RevTeX with 8 postscript figures included. To appear in
``Non Fermi Liquid Physics'', J. Phys:Cond. Matt. (1997
Concept for a Time-of-Flight Small Angle Neutron Scattering Instrument at the European Spallation Source
A new Small Angle Neutron Scattering instrument is proposed for the European
Spallation Source. The pulsed source requires a time-of-flight analysis of the
gathered neutrons at the detector. The optimal instrument length is found to be
rather large, which allows for a polarizer and a versatile collimation. The
polarizer allows for studying magnetic samples and incoherent background
subtraction. The wide collimation will host VSANS and SESANS options that
increase the resolution of the instrument towards um and tens of um,
respectively. Two 1m2 area detectors will cover a large solid angle
simultaneously. The expected gains for this new instrument will lie in the
range between 20 and 36, depending on the assessment criteria, when compared to
up-to-date reactor based instruments. This will open new perspectives for fast
kinetics, weakly scattering samples, and multi-dimensional contrast variation
studies.Comment: 18 pages, 10 figure
Thermal conductivity of Tl2Ba2Ca2Cu3O10 ceramics from 300 K down to 0.1 K
Thermal conductivity, [varkappa], of two ceramic samples of Tl2Ba2Ca2Cu3O10 has been measured over a temperature range from 300 K down to 0.1 K. At high temperatures, the data show features similar to the thermal conductivity of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O ceramics in both the magnitude and the temperature dependence. Specifically, a sudden increase in the thermal conductivity is observed at the onset of a superconducting transition near 120 K culminating in a pronounced maximum of [varkappa] around 75 K and an eventual rapid decrease of the thermal conductivity at lower temperatures. From 5 K down to 0.1 K we observe the thermal conductivity to decrease with an average power law exponent between 2.4 and 2.5. Such a temperature dependence is comparable with that for sintered Bi-Sr-Ca-Cu-O samples, but differs from the quadratic variation typical for Bi-Sr-Ca-Cu-O single crystals and the T-linear asymptotic behavior characteristic of Y-Ba-Cu-O and La-Sr-Cu-O ceramics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29278/1/0000337.pd
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