Neural networks for perpetual grouping

A number of researchers have investigated the application of neural networks to visual recognition, with much of the emphasis placed on exploiting the network's ability to generalise. However, despite the benefits of such an approach it is not at all obvious how networks can be developed which are capable of recognising objects subject to changes in rotation, translation and viewpoint. In this study, we suggest that a possible solution to this problem can be found by studying aspects of visual psychology and in particular, perceptual organisation. For example, it appears that grouping together lines based upon perceptually significant features can facilitate viewpoint independent recognition. The work presented here identifies simple grouping measures based on parallelism and connectivity and shows how it is possible to train multi-layer perceptrons (MLPs) to detect and determine the perceptual significance of any group presented. In this way, it is shown how MLPs which are trained via backpropagation to perform individual grouping tasks, can be brought together into a novel, large scale network capable of determining the perceptual significance of the whole input pattern. Finally the applicability of such significance values for recognition is investigated and results indicate that both the NILP and the Kohonen Feature Map can be trained to recognise simple shapes described in terms of perceptual significances. This study has also provided an opportunity to investigate aspects of the backpropagation algorithm, particularly the ability to generalise. In this study we report the results of various generalisation tests. In applying the backpropagation algorithm to certain problems, we found that there was a deficiency in performance with the standard learning algorithm. An improvement in performance could however, be obtained when suitable modifications were made to the algorithm. The modifications and consequent results are reported here

Are 11 Weeks Weak? A Conversation With Instructors

Undergraduate programs in the United States range from locally funded, two-year community colleges, to state and federally funded universities, as well as private, tuition-based institutions. Assumingly most programs attempt to facilitate a relevant and balanced curriculum that prepares students for the general and perhaps specific obstacles that they will experience in a professional environment. Successful curricula may also attempt to prepare students for the social, cultural and economic challenges that they will experience in their personal life. The question of how various programs implement this fundamental yet daunting task has been in the past and assuredly will remain a part of academia, research studies and discussions. In general, these debates relate to the breadth of a program. However, within this arena, the pertinent factor is a program’s length—the number of credit hours congruent to or with the duration of a quarter or a semester that are required to achieve a particular degree. This aspect may be of significance to prospective students, their parents, spouses and other individuals who potentially hold a role in the selection of the student’s educational process and future. Undeniable factors in the decision-process include admission’s work, the program itself, the degree offering, the reputation of the institution, cost of credit hours, the school’s physical location and its supporting environment—including housing accommodation, libraries, activity centers, proximity to family and workplace. Regardless of the various options, some individuals make the decision to enroll in an 11-week quarter-based educational model. The Art Institutes utilize this educational model at their thirty-five locations across the United States and two facilities in Canada. This system leads us to the question: do eleven weeks provide sufficient time for a student to interpret, analyze and demonstrate the course objectives? With an effort to advocate open-minded and non-conformist responses questions relating to this topic were asked in an informal setting—to new and experienced instructors who currently teach full or part-time at The Art Institute of Dallas. All possess a Masters or terminal degree in their fields of instruction and have been teaching in higher education for five or more years. Data from these conversations was gathered and has become the essence of this paper. Readers may assume current faculty advocate this model in order to maintain active employment. However, those assumptions are erroneous. The relevance of this research is important to prospective students, parents and all the individuals involved in higher education across the continuum of five- to seventeen-week terms. Those individuals can ‘hear’ the pros and cons (if any) of such a model from instructors themselves. This inquiry contributes to the conversations and value as found and defined by instructors. Via their research, the authors hope to facilitate a dialogue that advocates/or does not advocate the institution of an 11-week educational model amongst all the interested individuals in higher education. A deeper level of understanding and respect for instructors who successfully teach in quarter-based educational models can be obtained. Administrators may find value in this research for economic and accounting reasons. Both the authors clearly understand that the ‘instructor’ is only one component of any successful educational model. Opinions from others such as the students and alumni are also of immense value. These individuals will be addressed in their further studies

Oxidative cytotoxic agent withaferin A resensitizes temozolomide-resistant glioblastomas via MGMT depletion and induces apoptosis through Akt/mTOR pathway inhibitory modulation

Temozolomide (TMZ) has remained the chemotherapy of choice in patients with glioblastoma multiforme (GBM) primarily due to the lack of more effective drugs. Tumors, however, quickly develop resistance to this line of treatment creating a critical need for alternative approaches and strategies to resensitize the cells. Withaferin A (WA), a steroidal lactone derived from several genera of the Solanaceae plant family has previously demonstrated potent anti-cancer activity in multiple tumor models. Here, we examine the effects of WA against TMZ-resistant GBM cells as a monotherapy and in combination with TMZ. WA prevented GBM cell proliferation by dose-dependent G2/M cell cycle arrest and cell death through both intrinsic and extrinsic apoptotic pathways. This effect correlated with depletion of principle proteins of the Akt/mTOR and MAPK survival and proliferation pathways with diminished phosphorylation of Akt, mTOR, and p70 S6K but compensatory activation of ERK1/2. Depletion of tyrosine kinase cell surface receptors c-Met, EGFR, and Her2 was also observed. WA demonstrated induction of N-acetyl-L-cysteine-repressible oxidative stress as measured directly and through a subsequent heat shock response with HSP32 and HSP70 upregulation and decreased HSF1. Finally, pretreatment of TMZ-resistant GBM cells with WA was associated with O6-methylguanine-DNA methyltransferase (MGMT) depletion which potentiated TMZ-mediated MGMT degradation. Combination treatment with both WA and TMZ resulted in resensitization of MGMT-mediated TMZ-resistance but not resistance through mismatch repair mutations. These studies suggest great clinical potential for the utilization of WA in TMZ-resistant GBM as both a monotherapy and a resensitizer in combination with the standard chemotherapeutic agent TMZ

MARQUIS: A multiplex method for absolute quantification of peptides and posttranslational modifications

Absolute quantification of protein expression and posttranslational modifications by mass spectrometry has been challenging due to a variety of factors, including the potentially large dynamic range of phosphorylation response. To address these issues, we have developed MARQUIS—Multiplex Absolute Regressed Quantification with Internal Standards—a novel mass spectrometry-based approach using a combination of isobaric tags and heavy-labelled standard peptides, to construct internal standard curves for peptides derived from key nodes in signal transduction networks. We applied MARQUIS to quantify phosphorylation dynamics within the ​EGFR network at multiple time points following stimulation with several ligands, enabling a quantitative comparison of ​EGFR phosphorylation sites and demonstrating that receptor phosphorylation is qualitatively similar but quantitatively distinct for each ​EGFR ligand tested. MARQUIS was also applied to quantify the effect of ​EGFR kinase inhibition on glioblastoma patient-derived xenografts. MARQUIS is a versatile method, broadly applicable and extendable to multiple mass spectrometric platforms.United States-Israel Binational Science FoundationNational Institutes of Health (U.S.) (Grant U54 CA112967)National Institutes of Health (U.S.) (Grant R01 CA118705)National Institutes of Health (U.S.) (Grant R01 CA096504)Mayo Brain Tumor SPORE CA10896

Notes about the Caratheodory number

In this paper we give sufficient conditions for a compactum in $\mathbb R^n$ to have Carath\'{e}odory number less than $n+1$, generalizing an old result of Fenchel. Then we prove the corresponding versions of the colorful Carath\'{e}odory theorem and give a Tverberg type theorem for families of convex compacta

Estrogens and genomic instability in human cancer cells-involvement of Src/Raf/Erk signaling in micronucleus formation by estrogenic chemicals

This article is available open access through the publisher’s website. Copyright @ 2008 The Authors.Reports of the ability of estrogenic agents such as 17β-estradiol (E2), estriol (E3) and bisphenol A (BPA) to induce micronuclei (MN) in MCF-7 breast cancer cells have prompted us to investigate whether these effects are linked to activation of the estrogen receptor (ER) α. Coadministration of tamoxifen and the pure ER antagonist ICI 182 780 to cells treated with E2 and E3 did not lead to significant reductions in micronucleus frequencies. Since these antiestrogens interfere with the transcriptional activity of the ER and block promotion of ER-dependent gene expression, it appears that this process is not involved in micronucleus formation. However, ER activation also triggers rapid signaling via the Src/Raf/extracellular signal-regulated kinase (Erk) pathway. When MCF-7 cells were exposed to E2 and BPA in combination with the specific kinase inhibitors pyrazolopyrimidine and 2′-amino-3′-methoxyflavone, reductions in micronucleus frequencies occurred. These findings suggest that the Src/Raf/Erk pathway plays a role in micronucleus formation by estrogenic agents. Enhanced activation of the Src/Raf/Erk cascade disturbs the localization of Aurora B kinase to kinetochores, leading to a defective spindle checkpoint with chromosome malsegregation. Using antikinetochore CREST antibody staining, a high proportion of micronucleus containing kinetochores was observed, indicating that such processes are relevant to the induction of MN by estrogens. Our results suggest that estrogens induce MN by causing improper chromosome segregation, possibly by interfering with kinase signaling that controls the spindle checkpoint, or by inducing centrosome amplification. Our findings may have some relevance in explaining the effects of estrogens in the later stages of breast carcinogenesis.European Commissio