125 research outputs found
Knowledgezoom for java: A concept-based exam study tool with a zoomable open student model
This paper presents our attempt to develop a personalized exam preparation tool for Java/OOP classes based on a fine-grained concept model of Java knowledge. Our goal was to explore two most popular student model-based approaches: open student modeling and problem sequencing. The result of our work is a Java exam preparation tool, Knowledge Zoom. The tool combines an open concept-level student model component, Knowledge Explorer and a concept-based sequencing component, Knowledge Maximizer into a single interface. This paper presents both components of Knowledge Zoom, reports results of its evaluation, and discusses lessons learned. © 2013 IEEE
Pattern of regional metastasis in papillary thyroid cancer: our experience of 86 cases
Background: Papillary thyroid cancer (PTC) have a high propensity for regional metastasis which ranges from 30- 80%. The objective of the study is to assess the pattern of lymph node metastasis and to plan the extent of neck dissection accordingly. Though central neck dissection (CND) is routinely done in PTC but the indication of extent of neck dissection is still controversial.Methods: The medical records of 86 patients with PTC who underwent total thyroidectomy (TT) and neck dissection at Dr. B. Borooah Cancer Institute(BBCI) from January 2010 to December 2014 were retrospectively reviewed.Results: Out of 86 patients 22 were males and 64 were females. The median age of presentation was 40.0 years. 43 out of 86 patients (50%) had cervical lymph node metastasis. Ipsilateral nodal metastasis was found in 37 patients (43.0%) and contralateral metastasis was found in only 6 patients (7.0%).Tumors with size more than 3cm had ipsilateral nodal metastasis in 21(56.7%) patients which is statistically significant (p 0.03).A strong association was found between level VI and the ipsilateral group of lymph nodes involving level II,III,IV and V.Conclusions: Majority of patients present with multiple level nodal metastasis, with the central compartment commonly involved. In view of the high incidence of metastatic lymph nodes in levels II, III, IV and level VI ,our study supports the recommendation for posterolateral and anterior neck dissection in patients with clinically positive neck nodes and tumor with aggressive criteria
Antimicrobial Resistance in Gram Positive and Gram Negative Bacteria Progress and Challenges
Serious infections caused by bacteria that have become resistant to commonly used
antibiotics have become a major global healthcare problem in the 21st century.
Antibiotic resistance, initially a problem of the hospital setting associated with an
increased number of hospitals acquired infections usually in critically ill and
immuno-suppressed patients, has now extended into the community causing severe
infections difficult to diagnose and treat. In hospitals, most common resistant
bacteria include methicillin-resistant Staphylococcus aureus, vancomycin-resistant
enterococci and gram-negative rods including Enterobacteriaceae and Pseudomonas
aeruginosa. Vancomycin intermediate and resistant S. aureus, represent a new
treatment challenge. In the community, penicillin and macrolide-resistant
pneumococci developed several decades ago and are now present all over the world.
More recently, community-acquired methicillin-resistant S. aureus has become a
problem in several countries causing skin infections but also severe diseases. The
molecular mechanisms by which bacteria have become resistant to antibiotics are
diverse and complex. Bacteria have developed resistance to all different classes of
antibiotics discovered to date. The most frequent type of resistance is acquired and
transmitted horizontally via the conjugation of a plasmid. In recent times new
mechanisms of resistance have resulted in the simultaneous development of
resistance to several antibiotic classes creating very dangerous multidrug-resistant
(MDR) bacterial strains, some also known as 18 18superbugs 19 19. In many cases the use of
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antibiotics is unnecessary or questionable. The indiscriminate and inappropriate use
of antibiotics in outpatient clinics, hospitalized patients and in the food industry is
the single largest factor leading to antibiotic resistance. In recent years, the number
of new antibiotics licensed for human use in different parts of the world has been
lower than in the recent past. In addition, there has been less innovation in the field
of antimicrobial discovery research and development. The pharmaceutical industry,
large academic institutions or the government are not investing the necessary
resources to produce the next generation of newer safe and effective antimicrobial
drugs. In many cases, large pharmaceutical companies have terminated their antiinfective
research programs altogether due to economic reasons. The potential
negative consequences of all these events are relevant because they put society at
risk for the spread of potentially serious MDR bacterial infections
Evidence of a new shell closed nucleus governing slow quasi-fission
Mass distributions of fission fragments arising from the slow quasi-fission
process have been derived by comparing the measured distributions with the
theoretical distributions based on compound nuclear fission model for several
reactions. The mass-distributions corresponding to quasi-fission events for all
the systems show the following common features: (1) they are double peaked with
fixed peak-centroids and nearly same width at different incident energies, (2)
the yield of quasi-fission events decreases with the increasing projectile
energy, and (3) peak corresponding to lighter fragment is observed at A
96 for all the systems, whereas the peak of heavier fragment increases linearly
with the mass of the di-nuclear system. All the above observations are quite
similar to the ones observed in well known asymmetric fission of actinides,
thus providing clear evidences of shell effect in slow quasi-fission where the
lighter fragment is possibly nuclei around Zr, a new doubly magic
nucleus. This finding has great implications in the study of nuclear reactions,
structure and particularly in super-heavy element synthesis where quasi-fission
is synonymous
A multiscale experimental analysis of mechanical properties and deformation behavior of sintered copper–silicon carbide composites enhanced by high‑pressure torsion
Experiments were conducted to investigate, within the framework of a multiscale approach, the mechanical enhancement, deformation and damage behavior of copper–silicon carbide composites (Cu–SiC) fabricated by spark plasma sintering (SPS) and the combination of SPS with high-pressure torsion (HPT). The mechanical properties of the metal–matrix composites were determined at three different length scales corresponding to the macroscopic, micro- and nanoscale. Small punch testing was employed to evaluate the strength of composites at the macroscopic scale. Detailed analysis of microstructure evolution related to SPS and HPT, sample deformation and failure of fractured specimens was conducted using scanning and transmission electron microscopy. A microstructural study revealed changes in the damage behavior for samples processed by HPT and an explanation for this behavior was provided by mechanical testing performed at the micro- and nanoscale. The strength of copper samples and the metal–ceramic interface was determined by microtensile testing and the hardness of each composite component, corresponding to the metal matrix, metal–ceramic interface, and ceramic reinforcement, was measured using nano-indentation. The results confirm the advantageous effect of large plastic deformation on the mechanical properties of Cu–SiC composites and demonstrate the impact on these separate components on the deformation and damage type
A global reference database of crowdsourced cropland data collected using the Geo-Wiki platform
A global reference data set on cropland was collected through a crowdsourcing campaign using the Geo-Wiki crowdsourcing tool. The campaign lasted three weeks, with over 80 participants from around the world reviewing almost 36,000 sample units, focussing on cropland identification. For quality assessment purposes, two additional data sets are provided. The first is a control set of 1,793 sample locations validated by students trained in satellite image interpretation. This data set was used to assess the quality of the crowd as the campaign progressed. The second data set contains 60 expert validations for additional evaluation of the quality of the contributions. All data sets are split into two parts: the first part shows all areas classified as cropland and the second part shows cropland average per location and user. After further processing, the data presented here might be suitable to validate and compare medium and high resolution cropland maps generated using remote sensing. These could also be used to train classification algorithms for developing new maps of land cover and cropland extent
A global reference database of crowdsourced cropland data collected using the Geo-Wiki platform
A global reference data set on cropland was collected through a crowdsourcing campaign using the Geo-Wiki crowdsourcing tool. The campaign lasted three weeks, with over 80 participants from around the world reviewing almost 36,000 sample units, focussing on cropland identification. For quality assessment purposes, two additional data sets are provided. The first is a control set of 1,793 sample locations validated by students trained in satellite image interpretation. This data set was used to assess the quality of the crowd as the campaign progressed. The second data set contains 60 expert validations for additional evaluation of the quality of the contributions. All data sets are split into two parts: the first part shows all areas classified as cropland and the second part shows cropland average per location and user. After further processing, the data presented here might be suitable to validate and compare medium and high resolution cropland maps generated using remote sensing. These could also be used to train classification algorithms for developing new maps of land cover and cropland extent
ZnS nanocomposite formation: Effect of ZnS source concentration ratio
186-189Thin films of
ZnS-PVA nanocomposites have been prepared by chemical bath deposition (CBD)
method by varying the concentration ratio of sulphur to zinc sources. The
obtained films are characterized by XRD, TEM, UV-visible spectra, photoluminescence
(PL) spectra and current-voltage (I-V)
characteristics. The results show strong dependence on source concentration
ratio. There is an increase in particle size and decrease in band gap with
increase of S to Zn source ratio. PL spectra show decrease in intensity and
blue shift with the increase in this ratio
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