2,415 research outputs found
Ecohydrological Controls on Grass and Shrub Above-ground Net Primary Productivity in a Seasonally Dry Climate
Seasonally dry, waterâlimited regions are often coâdominated by distinct herbaceous and woody plant communities with contrasting ecohydrological properties. We investigated the shape of the aboveâground net primary productivity (ANPP) response to annual precipitation (Pa) for adjacent grassland and shrubland ecosystems in Southern California, with the goal of understanding the role of these ecohydrological properties on ecosystem function. Our synthesis of observations and modelling demonstrates grassland and shrubland exhibit distinct ANPPâPa responses that correspond with characteristics of the longâterm Pa distribution and mean water balance fluxes. For annual grassland, no ANPP occurs below a âprecipitation compensation point,â where bare soil evaporation dominates the water balance, and ANPP saturates above the Pawhere deep percolation and runoff contribute to the modelled water balance. For shrubs, ANPP increases at a lower and relatively constant rate across the Pa gradient, while deep percolation and runoff account for a smaller fraction of the modelled water balance. We identify precipitation seasonality, root depth, and water stress sensitivity as the main ecosystem properties controlling these responses. Observed ANPPâParesponses correspond to notably different patterns of rainâuse efficiency (RUE). Grass RUE exceeds shrub RUE over a wide range of typical Pa values, whereas grasses and shrubs achieve a similar RUE in particularly dry or wet years. Interâannual precipitation variability, and the concomitant effect on ANPP, plays a critical role in maintaining the balance of grass and shrub cover and ecosystemâscale productivity across this landscape
A simulation of the single scan accuracy of a two-dimensional pulsed surveillance radar
Bibliography: leaves 194-198.The following dissertation considers the single-scan two-dimensional positional accuracy of a pulsed surveillance radar. The theoretical aspects to the positional accuracy are considered and a generalized analytical approach is presented. Practical position estimators are often complex, and theoretical predictions of their performance generally yield unfriendly mathematical equations. In order to evaluate the performance of these estimators, a simulation method is described based on replicating the received video signal. The accuracy of such a simulation is determined largely by the accuracy of the models applied, and these are considered in detail. Different azimuth estimation techniques are described, and their performances are evaluated with the aid of the signal simulation. The best azimuth accuracy performance is obtained with the class of analogue processing estimators, but they are found to be more susceptible to interference than their binary processing counterparts. The class of binary processing estimators offer easily implemented techniques which are relatively insensitive to radar cross-section scintillation characteristics. A hybrid estimator, using both analogue and binary processing, is also evaluated and found to give an improved accuracy performance over the binary processing method while still maintaining the relative insensitivity to radar cross-section fluctuation
They live in indifference together: marriage mobility in Zeeland, The Netherlands
This article investigates developments in and antecedents of socially mixed marriage in the rural Dutch province of Zeeland during the long nineteenth century, taking individual and family histories, community contexts, and temporal influences into account. A government report of the 1850s said of Zeeland that farmers and workers lived "in indifference together". However, our analysis of about 163,000 marriage certificates reveals that 30 to 40 per cent of these rural inhabitants continued to marry outside their original social class. Multivariate logistic regressions show that heterogamous marriages can be explained first and foremost by the life-course experiences of grooms and brides prior to marriage. Previous transitions in their occupational careers (especially to non-rural occupations for grooms, and to service for brides), in their migration trajectories (particularly moves to urban areas), and changes in the sphere of personal relationships (entering widowhood, ageing) are crucial in understanding marriage mobility. © 2005 Internationaal Instituut voor Sociale Geschiedenis
Effectiveness of design codes for life cycle energy optimisation
The built environment is materially inefficient, with structural material wastage in the order of 50% being common. As operational energy consumption in buildings falls, due to continued tightening of regulations and improvements in the efficiency of energy generation and distribution, present inefficiencies in embodied energy use become increasingly significant in the calculation of whole life energy use. The status quo cannot continue if we are to meet carbon emissions reduction targets. We must now tackle embodied energy as vigorously as we have tackled operational energy in buildings in the past.Current design methods are poorly suited to controlling material inefficiency in design, which arises as a risk mitigation strategy against unknown loads and uncertain human responses to these loads. Prescriptive codes are intended to result in buildings capable of providing certain levels of performance. These performance levels are often based on small tests, and the actual performance of individual building designs is rarely fully assessed after construction. A new approach is required to drive the minimisation of embodied energy (lightweighting) through the collection of performance data on both structures and their occupants.This paper uses an industry facing survey to explore for the first time the potential use of performance measurement to create new drivers for lighter and more usable designs. The use of ubiquitous structural, human, and environmental sensing, combined with automated data fusion, data interpretation, and knowledge generation is now required to ensure that future generations of building designs are lightweight, lower-carbon, cheaper, and healthier
Metastatic poorlydifferentiatedadenocarcinoma of the sternum unsolved diagnosticallyby immunohistochemicalstaining:a case repo
ABSTRACT
A 42 year-old male admitted to Dr. Sardjito Hospital, Yogyakarta because of a painful sternal mass that was
becoming larger since 6 months before hospitalized. He was diagnosed as malignant thymoma based on
microscopic examination of specimen obtained from FNAB. Histological examination from biopsy specimen
showed a tumor, composed of epithelial cells and arranged in nests, solid, partly tubular and glandular structures considered thymic carcinoma with differential diagnosis a poorly differentiated adenocarcinoma. PAS staining was positive and PASdiastase was negative, considered that the cytoplasm contained glycogen. The tumor cells showed expression of polykeratin (CAM5.2, TTF1, and CD10). Neurogenic and neuroendocrine markers (5100, CD56, CD57). mesothelial markers (calretinin,EMA),and mesenchymal markers (vimentin, CD6,S,desmin, SMA) are negative. The impression was metastatic adenocarcinoma. In case of metastatic one could consider a metastasis of a lung adenocarcinoma or thyroid carcinoma (TTF1+, but CD10 expression did not fit) and renal cell carcinoma (CD10 +, but TTF1 did not fit). The final considered diagnosis was poorly differentiated adenocarcinoma, metastasis from the lung, thyroid, or kidney. The aim of this presented article is to report a difficultcase of metastatic poorly differentiated adenocarcinoma of the sternum in which immunohistochemical staining could not solve the morphological diagnostic problems, to emphasize the importance of clinicalinformation and good morphologicevaluation to determine the diagnosis
Direct observation of the high magnetic field effect on the Jahn-Teller state in TbVO4
We report the first direct observation of the influence of high magnetic
fields on the Jahn-Teller (JT) transition in TbVO4. Contrary to spectroscopic
and magnetic methods, X-ray diffraction directly measures the JT distortion;
the splitting between the (311)/(131) and (202)/(022) pairs of Bragg
reflections is proportional to the order parameter. Our experimental results
are compared to mean field calculations, taking into account all possible
orientations of the grains relative to the applied field, and qualitative
agreement is obtained.Comment: 11 pages, 4 figures, submitted to Phys. Rev. Let
Late-onset and acute presentation of Brown-Vialetto-Van Laere syndrome in a Brazilian family
Riboflavin transporter deficiency (formerly known as Brown-Vialetto-Van Laere [BVVL] or
Fazio-Londe syndrome) is a neurodegenerative disorder characterized by progressive bulbar
palsy with sensorineural deafness or bulbar hereditary neuropathy.1 It is caused by mutations in
the riboflavin transporter genes SLC52A2 (RFVT2) or SLC52A3 (RFVT3).2,3 It is a rare
syndrome with approximately 70 cases reported worldwide, with molecular diagnoses of
RFVT2 or RFVT3.
1,4 We have previously described the first Brazilian family with a clinical
diagnosis of BVVL.5
In this report, we extend the clinical spectrum associated with this family and describe a new
mutation related to the metabolism of riboflavin
Cranial unifocal langerhans cell histiocytosis in a female child: a difficult case with S-100 and CD1a immunonegativity
A 13-years old female child was carried to Dr. Sardjito General Hospital, Yogyakarta by her mother with chiefcomplaint of a mass on her forehead. Since eight months prior to her visiting, she had a mass on her forehead whichbecame larger slowly without tenderness and had no fever. Clinical examination revealed a well circumscribedmass, 3 cm in diameter, fixed, with rubbery consistency. The skull X-ray revealed a punch out lesion in frontal bone.The head CT scanning revealed a destruction of frontal bone. Clinical diagnosis of dermoid cyst was determined,excision and curettage was performed. Gross examination showed 2.5 cc fragmented tissue, brownish yellow, withrubbery consistency. A diagnosis of benign histiocytosis (Langerhans cell histiocytosis or non-Langerhans cellhistiocytosis) of frontal bone was determined based on morphological and immunohistochemical examination. Theaim of this presented article was to report a rare case of cranial unifocal Langerhans cell histiocytosis in a femalechild with S-100 and CD1a immunonegativity, and to discuss how to determine its diagnosis based on literaturereview.Key words: Langerhans cell histiocytosis - juvenile xanthogranuloma â reticulohistiocytoma - eosinophilic granulomaâ S100 â CD1
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