Presenting the cohomology of a Schubert variety: Proof of the minimality conjecture

A minimal presentation of the cohomology ring of the flag manifold $GL_n/B$ was given in [A. Borel, 1953]. This presentation was extended by [E. Akyildiz-A. Lascoux-P. Pragacz, 1992] to a non-minimal one for all Schubert varieties. Work of [Gasharov-Reiner, 2002] gave a short, i.e. polynomial-size, presentation for a subclass of Schubert varieties that includes the smooth ones. In [V. Reiner-A. Woo-A. Yong, 2011], a general shortening was found; it implies an exponential upper bound of $2^n$ on the number of generators required. That work states a minimality conjecture whose significance would be an exponential lower bound of $\sqrt{2}^{n+2}/\sqrt{\pi n}$ on the number of generators needed in worst case, giving the first obstructions to short presentations. We prove the minimality conjecture. Our proof uses the Hopf algebra structure of the ring of symmetric functions.Comment: 19 pages, 4 figures, to appear in J. London. Math. So

How content contributors assess and establish credibility on the web

The proliferation of user‐generated content (UGC) is one of the distinguishing characteristics of Web 2.0. Internet users contribute content online through platforms such as blogs, wikis, video sharing sites, and sites that allow user feedback. Yet little is known of the credibility practices of these content contributors. Through phone interviews conducted with 29 online content contributors, this study investigates how content contributors assess credibility when gathering information for their online content creation and mediation activities, as well as the strategies they use to establish the credibility of the content they create. These contributors reported that they engaged in content creation activities such as posting or commenting on blogs or online forums, rating or voting on online content, and uploading photos, music, or video. We found that credibility judgments made when gathering information for online content creation and mediation activities could be grouped into three levels: intuitive, heuristic, and strategy‐based. We identified three distinctive ways of establishing credibility that are applied during different phases of content contribution: ensuring credibility during the content creation phase; signaling credibility during the content presentation phase; and reinforcing credibility during the post‐production phase. We also discovered that content contributors tend to carry over the strategies they used for assessing credibility during information gathering to their strategies for establishing the credibility of their own content. Theoretical implications for credibility research and practical implications for developing information literacy programs are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90253/1/14504801163_ftp.pd

An online activity diary method for studying credibility assessment on the Web

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78324/1/1450460388_ftp.pd

A diary study of credibility assessment in everyday life information activities on the web: Preliminary findings

This study investigates how people's credibility assessment processes have evolved as they engage in increasingly diverse types of online activities beyond seeking for information or reading online news. Using an online activity diary method, information on people's online activities and their associated credibility assessment processes were collected at multiple points throughout the day for three days. This paper reports on a preliminary analysis of 2,471 diary entries received from 333 respondents. Content analysis was applied to people's descriptions of their online activities, yielding 17 different types of information objects and 26 categories of online content. People's credibility judgments were examined on three levels: construct, heuristics, and interaction. The results, although preliminary, indicate that distinct credibility assessment heuristics are in fact emerging as people engage in online activities involving more user-generated and multimedia content. The unique contribution of this paper is its identification of the importance of taking a heuristic approach to credibility assessment by studying a large sample of heavy Internet users within the context of the everyday life information activities they conduct online.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83172/1/14504701182_ftp.pd

Recurrent deletions of ULK4 in schizophrenia : a gene crucial for neuritogenesis and neuronal motility

Peer reviewedPublisher PD

Living donor liver transplantation without the use of blood products.

We report on two patients who presented with unresectable hepatocellular carcinoma complicating hepatitis B liver cirrhosis. After evaluation, both patients were accepted for liver transplantation. Being aware of the scarce availability of cadaveric liver grafts and the long waiting time, family members volunteered to be donors for the two patients. Living donor liver transplantation using right lobe liver grafts, including the middle hepatic vein, was subsequently performed without the use of blood products in both the donors and recipients. All involved recovered uneventfully from their respective operations.published_or_final_versio

Changes in the Intensity of Flat Communal Spaces in the New Normal Era of Pandemic COVID-19 (Case Study of Penjaringan Sari Surabaya Flats)

One of the necessities of apartment dwellers is social interaction, which occurs in communal areas. As a result of the COVID-19 epidemic, there are restrictions on social interaction and a call to remain at home. The COVID-19 epidemic alters the function of social rooms in apartments. This study employs a qualitative descriptive approach, characterizing the pattern using a rationalistic approach and explaining the condition of the item. This study aims to determine the number and impact of changes in the intensity of the communal space in apartment buildings as a space for social contact between inhabitants in the new normal period. Changes in the utilization pattern of community space in flats for formal activities, such as the communal, space in the RW and field halls with RT/RW meeting activities, range from high to low intensity. In the meantime, the level of informal activities in communal spaces such as the lobby, gardens/gazebos, and kiosks tends to grow, as speaking, sitting, and playing become more prevalent. Observations indicate that physical adaptations to this pandemic condition remain minimal, at only 17 percent. This is due to a lack of finance and public information regarding how to alter the buildings physical components in response to the epidemic. As a result of the cancellation of many gathering events, such as RT/RW meetings, routine recitations, etc., the non-physical level of the epidemic is relatively high, at approximately 66 percent

RelB Expression Determines the Differential Effects of Ascorbic Acid in Normal and Cancer Cells

Cancer cells typically experience higher oxidative stress than normal cells, such that elevating pro-oxidant levels can trigger cancer cell death. Although pre-exposure to mild oxidative agents will sensitize cancer cells to radiation, this pre-exposure may also activate the adaptive stress defense system in normal cells. Ascorbic acid is a prototype redox modulator that when infused intravenously appears to kill cancers without injury to normal tissues; however, the mechanisms involved remain elusive. In this study, we show how ascorbic acid kills cancer cells and sensitizes prostate cancer to radiation therapy while also conferring protection upon normal prostate epithelial cells against radiation-induced injury. We found that the NF-κB transcription factor RelB is a pivotal determinant in the differential radiosensitization effects of ascorbic acid in prostate cancer cells and normal prostate epithelial cells. Mechanistically, high reactive oxygen species concentrations suppress RelB in cancer cells. RelB suppression decreases expression of the sirtuin SIRT3 and the powerful antioxidant MnSOD, which in turn increases oxidative and metabolic stresses in prostate cancer cells. In contrast, ascorbic acid enhances RelB expression in normal cells, improving antioxidant and metabolic defenses against radiation injury. In addition to showing how RelB mediates the differential effects of ascorbic acid on cancer and normal tissue radiosensitivities, our work also provides a proof of concept for the existence of redox modulators that can improve the efficacy of radiotherapy while protecting against normal tissue injury in cancer settings

Glycyrrhizic Acid Can Attenuate Metabolic Deviations Caused by a High-Sucrose Diet without Causing Water Retention in Male Sprague-Dawley Rats

Glycyrrhizic acid (GA) ameliorates many components of the metabolic syndrome, but its potential therapeutic use is marred by edema caused by inhibition of renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). We assessed whether 100 mg/kg per day GA administered orally could promote metabolic benefits without causing edema in rats fed on a high-sucrose diet. Groups of eight male rats were fed on one of three diets for 28 days: normal diet, a high-sucrose diet, or a high-sucrose diet supplemented with GA. Rats were then culled and renal 11β-HSD2 activity, as well as serum sodium, potassium, angiotensin II and leptin levels were determined. Histological analyses were performed to assess changes in adipocyte size in visceral and subcutaneous depots, as well as hepatic and renal tissue morphology. This dosing paradigm of GA attenuated the increases in serum leptin levels and visceral, but not subcutaneous adipocyte size caused by the high-sucrose diet. Although GA decreased renal 11β-HSD2 activity, it did not affect serum electrolyte or angiotensin II levels, indicating no onset of edema. Furthermore, there were no apparent morphological changes in the liver or kidney, indicating no toxicity. In conclusion, it is possible to reap metabolic benefits of GA without edema using the current dosage and treatment time

Improving Sparse Representation-Based Classification Using Local Principal Component Analysis

Sparse representation-based classification (SRC), proposed by Wright et al., seeks the sparsest decomposition of a test sample over the dictionary of training samples, with classification to the most-contributing class. Because it assumes test samples can be written as linear combinations of their same-class training samples, the success of SRC depends on the size and representativeness of the training set. Our proposed classification algorithm enlarges the training set by using local principal component analysis to approximate the basis vectors of the tangent hyperplane of the class manifold at each training sample. The dictionary in SRC is replaced by a local dictionary that adapts to the test sample and includes training samples and their corresponding tangent basis vectors. We use a synthetic data set and three face databases to demonstrate that this method can achieve higher classification accuracy than SRC in cases of sparse sampling, nonlinear class manifolds, and stringent dimension reduction.Comment: Published in "Computational Intelligence for Pattern Recognition," editors Shyi-Ming Chen and Witold Pedrycz. The original publication is available at http://www.springerlink.co