751 research outputs found
A new geometric approach to problems in birational geometry
A classical set of birational invariants of a variety are its spaces of
pluricanonical forms and some of their canonically defined subspaces. Each of
these vector spaces admits a typical metric structure which is also
birationally invariant. These vector spaces so metrized will be referred to as
the pseudonormed spaces of the original varieties. A fundamental question is
the following: given two mildly singular projective varieties with some of the
first variety's pseudonormed spaces being isometric to the corresponding ones
of the second variety's, can one construct a birational map between them which
induces these isometries? In this work a positive answer to this question is
given for varieties of general type. This can be thought of as a theorem of
Torelli type for birational equivalence.Comment: 13 pages, to appear in PNA
Mycobacterium tuberculosis and M. bovis infection in Feedlot Deer (Cervus unicolor swinhoei and C. nippon taiouanus) in Taiwan
Background/purposeMycobacterium bovis frequently infects wild and farm deer species with tuberculosis. This study investigated mycobacterial infection in two native deer species Cervus unicolor swinhoei (Formosan Sambar, Sambar) and C. nippon taiouanus (Formasan Sika, Sika).MethodsBased on different sampling sources of 19 intradermal tuberculin test (ITT) Sambar, mycobacterial infection and/or species were detected by acid-fast stain, duplex polymerase chain reaction (PCR) and multiplex nested PCR (mnPCR) methods, traditional mycobacterial culture and gross lesion. Blood samples of 167 Sambar deer and 147 Sika deer were then tested by duplex PCR and mnPCR methods to investigate the prevalence of mycobacterial infection. Sequence variations of these mycobacterial species were analyzed as well.ResultsDuplex PCR and mnPCR assays could differentiate between MTBC (M. bovis and M. tuberculosis) and M. avium, as well as between M. bovis and M. tuberculosis, respectively. These PCR methods showed a higher detection rate than traditional culture and matched the gross lesions examined in 19 ITT-examined Sambar. Therefore, the mycobacterial infection in blood samples of 314 deer samples was detected using these PCR methods. Duplex PCR and mnPCR showed an identical prevalence of 16.1% in Sambar and 8.2% in Sika and a significant difference in prevalence between these two deer species. M. bovis and M. tuberculosis were the species detected in feedlot Sambar and Sika. M. tuberculosis was found only and first in Sambar fed in central Taiwan. Sequence analysis revealed diverse genetic variations in M. bovis and M. tuberculosis associated with deer subspecies.ConclusionMultiplex PCR methods were established, and M. bovis and M. tuberculosis were identified in feedlot deer in Taiwan. Sequence variations indicated diverse sources of both mycobacterial species
Discontinuity of Maximum Entropy Inference and Quantum Phase Transitions
In this paper, we discuss the connection between two genuinely quantum
phenomena --- the discontinuity of quantum maximum entropy inference and
quantum phase transitions at zero temperature. It is shown that the
discontinuity of the maximum entropy inference of local observable measurements
signals the non-local type of transitions, where local density matrices of the
ground state change smoothly at the transition point. We then propose to use
the quantum conditional mutual information of the ground state as an indicator
to detect the discontinuity and the non-local type of quantum phase transitions
in the thermodynamic limit.Comment: Major revision. 26 pages, 12 figure
THE RELATIONSHIPS AMONG LMX, PSYCHOLOGICAL EMPOWERMENT, MOTIVATIONAL ORIENTATIONS AND INNOVATIVE BEHAVIOR
ABSTRACT In the past study, many researchers believed that leader-member exchange (LMX) had a significant influence on employee innovative behavior. This study extends previous research by examining the mediating role played by employee perceived psychological empowerment. This study also explores whether employees" motivational orientations have significant moderating effects on the relationship between employees" psychological empowerment and their innovative behaviors. Finally, this study examines whether the mediating effect of employees" psychological empowerment on the relation between LMX and innovative behaviors is, in turn, moderated by motivational orientations. Data were collected from 359 employees and their immediate supervisors in 46 companies in Taiwan. We tested the proposed relationships with robust data analytic techniques. Results were consistent with the hypothesized conceptual scheme, in that psychological empowerment mediated the relationship between LMX and innovative behavior when intrinsic or extrinsic motivation was high, but not when intrinsic or extrinsic motivation was low. On the basis of these findings, we conclude that the connection between LMX and innovative behavior in situations is more complex than was previously believed -there-by yielding a pattern of moderated mediation. JEL Classifications: M12, C12, L2
Projected Increase of the East Asian Summer Monsoon (Meiyu) in Taiwan by Climate Models With Variable Performance
The active phase of the East Asian summer monsoon (EASM) in Taiwan during May and June, known as Meiyu, produces substantial precipitation for water uses in all sectors of society. Following a companion study that analysed the historical increase in the Meiyu precipitation, the present study conducted model evaluation and diagnosis based on the EASM lifecycle over Taiwan. Higher and lower skill groups were identified from 17 Couple Model Intercomparison Project Phase 5 (CMIP5) models, with five models in each group. Despite the difference in model performance, both groups projected a substantial increase in the Meiyu precipitation over Taiwan. In the higher skill group, weak circulation changes and reduced low‐level convergence point to a synoptically unfavourable condition for precipitation. In the lower skill group, intensified low‐level southwesterly winds associated with a deepened upper level trough enhance moisture pooling. Thus, the projected increase in Meiyu precipitation will likely occur through the combined effects of (1) the extension of a strengthened North Pacific anticyclone enhancing southwesterlies; and (2) more systematically, the Clausius–Clapeyron relationship that increases precipitation intensity in a warmer climate. The overall increase in the Meiyu precipitation projected by climate models of variable performance supports the observed tendency toward more intense rainfall in Taiwan and puts its early June 2017 extreme precipitation events into perspective
Validation of bidimensional measurement in nasopharyngeal carcinoma
<p>Abstract</p> <p>Background</p> <p>Our previous study showed a close relationship between computed tomography (CT)-derived bidimensional measurement of primary tumor and retropharyngeal nodes (BDMprn) and gross tumor volume of primary tumor and retropharyngeal nodes (GTVprn) in nasopharyngeal carcinoma (NPC) and better prognosis for NPC patients with smaller BDMprn. In this study, we report the results on of a study to validate the use of BDM in a separate cohort of NPC patients.</p> <p>Methods</p> <p>We retrospectively reviewed 103 newly diagnosed NPC cases who were treated with radiotherapy/concurrent chemoradiotherapy (CCRT) or CCRT with adjuvant chemotherapy from 2002 to 2009. We used magnetic resonance imaging (MRI) to measure BDMprn. We calculated overall survival, recurrence-free and distant metastasis-free survival curves and set a BDMprn cut off point to categorize patients into a high- or low-risk group. We then used Cox proportional hazard model to evaluate the prognostic influence of BDMprn after correcting age, gender and chemotherapy status.</p> <p>Results</p> <p>After adjusting for age, gender, and chemotherapy status, BDMprn remained an independent prognostic factor for distant metastasis [Hazard ratio (HR) = 1.046; <it>P </it>= 0.042] and overall survival (HR = 1.012; <it>P </it>= 0.012). Patients with BDMprn < 15 cm<sup>2 </sup>had a greater 3-year overall survival rate than those with BDMprn ≧ 15 cm<sup>2 </sup>(92.3% vs. 73.7%; <it>P </it>= 0.009). They also had a greater 3-year distant metastasis-free survival (94% vs.75%; <it>P </it>= 0.034).</p> <p>Conclusion</p> <p>The predictive ability of BDMprn was validated in a separate NPC cohort. A BDMprn of 15 cm<sup>2 </sup>can be used to separate NPC patients into high- and low-risk groups and predict survival rates and metastasis potential. It can, therefore, be used as a reference to design clinical trials, predict prognosis, and make treatment decisions.</p
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Sialylation of vasorin by ST3Gal1 facilitates TGF-β1-mediated tumor angiogenesis and progression.
ST3Gal1 is a key sialyltransferase which adds α2,3-linked sialic acid to substrates and generates core 1 O-glycan structure. Upregulation of ST3Gal1 has been associated with worse prognosis of breast cancer patients. However, the protein substrates of ST3Gal1 implicated in tumor progression remain elusive. In our study, we demonstrated that ST3GAL1-silencing significantly reduced tumor growth along with a notable decrease in vascularity of MCF7 xenograft tumors. We identified vasorin (VASN) which was shown to bind TGF-β1, as a potential candidate that links ST3Gal1 to angiogenesis. LC-MS/MS analysis of VASN secreted from MCF7, revealed that more than 80% of its O-glycans are sialyl-3T and disialyl-T. ST3GAL1-silencing or desialylation of VASN by neuraminidase enhanced its binding to TGF-β1 by 2- to 3-fold and thereby dampening TGF-β1 signaling and angiogenesis, as indicated by impaired tube formation of HUVECs, suppressed angiogenesis gene expression and reduced activation of Smad2 and Smad3 in HUVEC cells. Examination of 114 fresh primary breast cancer and their adjacent normal tissues showed that the expression levels of ST3Gal1 and TGFB1 were high in tumor part and the expression of two genes was positively correlated. Kaplan Meier survival analysis showed a significantly shorter relapse-free survival for those with lower expression VASN, notably, the combination of low VASN with high ST3GAL1 yielded even higher risk of recurrence (p = 0.025, HR = 2.967, 95% CI = 1.14-7.67). Since TGF-β1 is known to transcriptionally activate ST3Gal1, our findings illustrated a feedback regulatory loop in which TGF-β1 upregulates ST3Gal1 to circumvent the negative impact of VASN
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