Methods of tropical optimization in rating alternatives based on pairwise comparisons

We apply methods of tropical optimization to handle problems of rating alternatives on the basis of the log-Chebyshev approximation of pairwise comparison matrices. We derive a direct solution in a closed form, and investigate the obtained solution when it is not unique. Provided the approximation problem yields a set of score vectors, rather than a unique (up to a constant factor) one, we find those vectors in the set, which least and most differentiate between the alternatives with the highest and lowest scores, and thus can be representative of the entire solution.Comment: 9 pages, presented at the Annual Intern. Conf. of the German Operations Research Society (GOR), Helmut Schmidt University Hamburg, Germany, August 30 - September 2, 201

MMP14 regulates the lineage progression of hypertrophic chondrocytes

It is traditionally believed that chondrocytes and osteoblasts are two separate lineages with hypertrophic chondrocytes (HCs) being the terminal stage of chondrocyte differentiation, culminating in apoptosis. However, we have shown that HCs can contribute to the full osteoblast (Obs) lineage in vivo. MMP14 is a transmembrane matrix metalloproteinase responsible for matrix remodeling that is highly expressed at the chondro‐osseous junction which coincides with the transition from HCs to Obs. Knockout of Mmp14 in mice results in impaired endochondral ossification. To test whether loss of MMP14 has an impact on the HC to Obs transition, we have employed a genetic recombination approach to track and compare the fate of HCs in wild‐type and Mmp14 conditional and total null mutants. Both complete and conditional deletion of MMP14 activity results in increased number of HC‐descendent cells in the trabecular bone. Surprisingly, conditional knockout of Mmp14 in HC‐descendent cells results in increased trabecular bone formation. Our results suggest that MMP14 in general negatively regulates HC to Obs transition.postprin

On pairwise comparison matrices that can be made consistent by the modification of a few elements

Pairwise comparison matrices are often used in Multi-attribute Decision Making forweighting the attributes or for the evaluation of the alternatives with respect to a criteria. Matrices provided by the decision makers are rarely consistent and it is important to index the degree of inconsistency. In the paper, the minimal number of matrix elements by the modification of which the pairwise comparison matrix can be made consistent is examined. From practical point of view, the modification of 1, 2, or, for larger matrices, 3 elements seems to be relevant. These cases are characterized by using the graph representation of the matrices. Empirical examples illustrate that pairwise comparison matrices that can be made consistent by the modification of a few elements are present in the applications

Writing with others in wiki: an investigation of student collaborative writing in English among Chinese secondary students

The Conference program's website is located at http://dgi-info.informationsassistent.de/index.php/dgi-eigenveranstaltungen/dgi-konferenz/dgi-konferenz-2012/programmSession 3: E-Learning & Knowledge DistributionWikis have become popular in the educational setting due to their potential to facilitate learning. It has increasingly been used in collaborative writing contexts; although in-depth explorations of the processes and interactions among students using wiki for collaborative writing projects is still lacking. This study aims to investigate how secondary school students in a Hong Kong school used wiki for collaborative writing. Data were obtained from analyzing the revision histories and the contents of the wiki pages. Results indicated that there was a tendency among students to add or edit the page contents rather than delete or organize them. Second, the use of wikis does not automatically guarantee the participation of all students in the writing process. Third, work is unevenly distributed among the group members. Fourth, evidence of collaboration was found in the comments and replies to the comments section. Theoretical and practical implications are discussed.postprin

Pulmonary artery sarcoma diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration

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High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients

Previous work on the subclones within Escherichia coli ST131 predominantly involved isolates from Western countries. This study assessed the prevalence and antimicrobial resistance attributed to this clonal group. A total of 340 consecutive, non-duplicated urinary E. coli isolates originating from four clinical laboratories in Hong Kong in 2013 were tested. ST131 prevalence among the total isolates was 18.5 % (63/340) and was higher among inpatient isolates (23.0 %) than outpatient isolates (11.8 %, P<0.001), and higher among isolates from patients aged ≥65 years than from patients aged 18–50 years and 51–64 years (25.4 vs 3.4 and 4.0 %, respectively, P<0.001). Of the 63 ST131 isolates, 43 (68.3 %) isolates belonged to the H30 subclone, whereas the remaining isolates belonged to H41 (n = 17), H54 (n = 2) and H22 (n = 1). All H30 isolates were ciprofloxacin-resistant, of which 18.6 % (8/43) belonged to the H30-Rx subclone. Twenty-six (41.3 %) ST131 isolates were ESBL-producers, of which 19 had bla CTX-M-14 (12 non-H30-Rx, two H30-Rx and five H41), six had bla CTX-M-15 (five non-H30-Rx and one H30-Rx) and one was bla CTX-M-negative (H30). In conclusion, ST131 accounts for a large share of the antimicrobial-resistant E. coli isolates from geriatric patients. Unlike previous reports, ESBL-producing ST131 strains mainly belonged to non-H30-Rx rather than the H30-Rx subclone, with bla CTX-M-14 as the dominant enzyme type.postprin

Microwave enhanced ion-cut silicon layer transfer

Microwave heating has been used to decrease the time required for exfoliation of thin single-crystalline silicon layers onto insulator substrates using ion-cut processing. Samples exfoliated in a 2.45 GHz, 1300 W cavity applicator microwave system saw a decrease in incubation times as compared to conventional anneal processes. Rutherford backscattering spectrometry, cross sectional scanning electron microscopy, cross sectional transmission electron microscopy, and selective aperture electron diffraction were used to determine the transferred layer thickness and crystalline quality. The surface quality was determined by atomic force microscopy. Hall measurements were used to determine electrical properties as a function of radiation repair anneal times. Results of physical and electrical characterizations demonstrate that the end products of microwave enhanced ion-cut processing do not appreciably differ from those using more traditional means of exfoliation. © 2007 American Institute of Physics

On reducing inconsistency of pairwise comparison matrices below an acceptance threshold

A recent work of the authors on the analysis of pairwise comparison matrices that can be made consistent by the modification of a few elements is continued and extended. Inconsistency indices are defined for indicating the overall quality of a pairwise comparison matrix. It is expected that serious contradictions in the matrix imply high inconsistency and vice versa. However, in the 35-year history of the applications of pairwise comparison matrices, only one of the indices, namely CR proposed by Saaty, has been associated to a general level of acceptance, by the well known ten percent rule. In the paper, we consider a wide class of inconsistency indices, including CR, CM proposed by Koczkodaj and Duszak and CI by Pel\'aez and Lamata. Assume that a threshold of acceptable inconsistency is given (for CR it can be 0.1). The aim is to find the minimal number of matrix elements, the appropriate modification of which makes the matrix acceptable. On the other hand, given the maximal number of modifiable matrix elements, the aim is to find the minimal level of inconsistency that can be achieved. In both cases the solution is derived from a nonlinear mixed-integer optimization problem. Results are applicable in decision support systems that allow real time interaction with the decision maker in order to review pairwise comparison matrices.Comment: 20 page

Treatment of severe acute respiratory syndrome with lopinavir/ritonavir: A multicentre retrospective matched cohort study

Objectives. To investigate the possible benefits and adverse effects of the addition of lopinavir/ritonavir to a standard treatment protocol for the treatment of severe acute respiratory syndrome. Design. Retrospective matched cohort study. Setting. Four acute regional hospitals in Hong Kong. Patients and methods. Seventy-five patients with severe acute respiratory syndrome treated with lopinavir/ritonavir in addition to a standard treatment protocol adopted by the Hospital Authority were matched with controls retrieved from the Hospital Authority severe acute respiratory syndrome central database. Matching was done with respect to age, sex, the presence of co-morbidities, lactate dehydrogenase level and the use of pulse steroid therapy. The 75 patients treated with lopinavir/ritonavir were divided into two subgroups for analysis: lopinavir/ritonavir as initial treatment, and lopinavir/ritonavir as rescue therapy. These groups were compared with matched cohorts of 634 and 343 patients, respectively. Outcomes including overall death rate, oxygen desaturation, intubation rate, and use of pulse methylprednisolone were reviewed. Results. The addition of lopinavir/ritonavir as initial treatment was associated with a reduction in the overall death rate (2.3%) and intubation rate (0%), when compared with a matched cohort who received standard treatment (15.6% and 11.0% respectively, P<0.05) and a lower rate of use of methylprednisolone at a lower mean dose. The subgroup who had received lopinavir/ritonavir as rescue therapy, showed no difference in overall death rate and rates of oxygen desaturation and intubation compared with the matched cohort, and received a higher mean dose of methylprednisolone. Conclusion. The addition of lopinavir/ritonavir to a standard treatment protocol as an initial treatment for severe acute respiratory syndrome appeared to be associated with improved clinical outcome. A randomised double-blind placebo-controlled trial is recommended during future epidemics to further evaluate this treatment.published_or_final_versio

Plasma hydrogenation of strained Si/SiGe/Si heterostructure for layer transfer without ion implantation

We have developed an innovative approach without the use of ion implantation to transfer a high-quality thin Si layer for the fabrication of silicon-on-insulator wafers. The technique uses a buried strained SiGe layer, a few nanometers in thickness, to provide H trapping centers. In conjunction with H plasma hydrogenation, lift-off of the top Si layer can be realized with cleavage occurring at the depth of the strained SiGe layer. This technique avoids irradiation damage within the top Si layer that typically results from ion implantation used to create H trapping regions in the conventional ion-cut method. We explain the strain-facilitated layer transfer as being due to preferential vacancy aggregation within the strained layer and subsequent trapping of hydrogen, which lead to cracking in a well controlled manner. © 2005 American Institute of Physics