Generalized feedback vertex set problems on bounded-treewidth graphs: chordality is the key to single-exponential parameterised algorithms

It has long been known that Feedback Vertex Set can be solved in time 2^O(w log w)n^O(1) on graphs of treewidth w, but it was only recently that this running time was improved to 2^O(w)n^O(1), that is, to single-exponential parameterized by treewidth. We investigate which generalizations of Feedback Vertex Set can be solved in a similar running time. Formally, for a class of graphs P, Bounded P-Block Vertex Deletion asks, given a graph G on n vertices and positive integers k and d, whether G contains a set S of at most k vertices such that each block of G-S has at most d vertices and is in P. Assuming that P is recognizable in polynomial time and satisfies a certain natural hereditary condition, we give a sharp characterization of when single-exponential parameterized algorithms are possible for fixed values of d: - if P consists only of chordal graphs, then the problem can be solved in time 2^O(wd^2) n^{O}(1), - if P contains a graph with an induced cycle of length ell>= 4, then the problem is not solvable in time 2^{o(w log w)} n^O(1)} even for fixed d=ell, unless the ETH fails. We also study a similar problem, called Bounded P-Component Vertex Deletion, where the target graphs have connected components of small size instead of having blocks of small size, and present analogous results

Parameterized Streaming Algorithms for Min-Ones d-SAT

In this work, we initiate the study of the Min-Ones d-SAT problem in the parameterized streaming model. An instance of the problem consists of a d-CNF formula F and an integer k, and the objective is to determine if F has a satisfying assignment which sets at most k variables to 1. In the parameterized streaming model, input is provided as a stream, just as in the usual streaming model. A key difference is that the bound on the read-write memory available to the algorithm is O(f(k) log n) (f: N -> N, a computable function) as opposed to the O(log n) bound of the usual streaming model. The other important difference is that the number of passes the algorithm makes over its input must be a (preferably small) function of k. We design a (k + 1)-pass parameterized streaming algorithm that solves Min-Ones d-SAT (d >= 2) using space O((kd^(ck) + k^d)log n) (c > 0, a constant) and a (d + 1)^k-pass algorithm that uses space O(k log n). We also design a streaming kernelization for Min-Ones 2-SAT that makes (k + 2) passes and uses space O(k^6 log n) to produce a kernel with O(k^6) clauses. To complement these positive results, we show that any k-pass algorithm for or Min-Ones d-SAT (d >= 2) requires space Omega(max{n^(1/k) / 2^k, log(n / k)}) on instances (F, k). This is achieved via a reduction from the streaming problem POT Pointer Chasing (Guha and McGregor [ICALP 2008]), which might be of independent interest. Given this, our (k + 1)-pass parameterized streaming algorithm is the best possible, inasmuch as the number of passes is concerned. In contrast to the results of Fafianie and Kratsch [MFCS 2014] and Chitnis et al. [SODA 2015], who independently showed that there are 1-pass parameterized streaming algorithms for Vertex Cover (a restriction of Min-Ones 2-SAT), we show using lower bounds from Communication Complexity that for any d >= 1, a 1-pass streaming algorithm for Min-Ones d-SAT requires space Omega(n). This excludes the possibility of a 1-pass parameterized streaming algorithm for the problem. Additionally, we show that any p-pass algorithm for the problem requires space Omega(n/p)

Anthropological Study of Shain Library: Uses, Perceptions, and Recommendations

In the spring of 2009 professor Benoit’s Applied Anthropology class conducted a comprehensive study on Connecticut College’s Shain Library. The class met with the library staff multiple times before deciding how to tackle the project. The research question posed was, how do students use and perceive the library? Does the library satisfy student’s needs, and if not what changes could be implemented to better the student body? The class began by submitting a proposal of our project to the Institutional Review Board, and then proceeded with the investigation. Though the topic as a whole is an examination of Shain Library each member of the class took on a specific aspects of the research. The topics covered range from study habits such as multitasking to how students utilize library resources outside of the library. The class created a DVD of their research and presented their findings to the library staff. This is the complete report of the research to compliment the DVD presentation

Design, navigation, and structure of a hypermedia application for the teaching–learning of pneumatic engineering design drawing

This article presents a hypermedia application used to study pneumatics that serves to support the lecturer in the lecture hall and as a self-study tool for the student. The reason behind the creation of this application is as follows: currently, there is no application in the market, which is equipped with a navigational system to guide the student through this subject matter, which has a system for self-assessment, and a system to identify those concepts that are of greatest interest or difficulty for the student. The proposed system monitors the time each user spends studying each section, as well as the dates on which each one was studied. Moreover, students are able to monitor their progress in learning the subject matter and identify those areas in which they have to improve. They are also able to simulate any pneumatic circuit in order to check its feasibility or detect any errors. The application has an open, modular structure, which enables changes to be made without its structure being affected. Use of the hypermedia application has supported the tutorial work of lecturers and reduced time spent elaborating on subject matter in the lecture hall, at the same time as facilitating its study

Holistic management of live animals confiscated from illegal wildlife trade

Practitioner's Perspectiv

The Autoimmune Regulator AIRE in Thymoma Biology: Autoimmunity and Beyond

Abstract:Thymomas are tumors of thymic epithelial cells. They associate more often than any other human tumors with various autoimmune diseases; myasthenia gravis is the commonest, occurring in 10–50% of thymoma patients, depending on the World Health Organization-defined histologic subtype. Most thymomas generate many polyclonal maturing T lymphocytes but in disorganized microenvironments Failure to induce self-tolerance may be a key factor leading to the export of potentially autoreactive CD4+ progeny, thus predisposing to autoimmune diseases. Normally, the master Autoimmune Regulator promotes expression of peripheral tissue-restricted antigens such as insulin by medullary thymic epithelial cells and induction of tolerance to them. The failure of ∼95% of thymomas to express autoimmune regulator is another feature potentially contributing to autoimmunity

Parameterized Streaming Algorithms for Min-Ones d-SAT

International audienc

PCR-free method detects high frequency of genomic instability in prostate cancer

Most studies of tumor instability are PCR-based. PCR-based methods may underestimate mutation frequencies of heterogeneous tumor genomes. Using a novel PCR-free random cloning/sequencing method, we analyzed 100 kb of total genomic DNA from blood lymphocytes, normal prostate and tumor prostate taken from six individuals. Variations were identified by comparison of the sequence of the cloned fragments with the nr-database in Genbank. After excluding known polymorphisms (by comparison to the NCBI dbSNP), we report a significant over-representation of variants in the tumors: 0.66 variations per kilobase of sequence, compared with the corresponding normal prostates (0.14 variations/kb) or blood (0.09 variations/kb). Extrapolating the observed difference between tumor and normal prostate DNA, we estimate 1.8 million somatic (de novo) alterations per tumor cell genome, a much higher frequency than previous measurements obtained by mostly PCR-based methods in other tumor types. Moreover, unlike the normal prostate and blood, most of the tumor variations occur in a specific motif (P = 0.046), suggesting common etiology. We further report high tumor cell-to-cell heterogeneity. These data have important implications for selecting appropriate technologies for cancer genome projects as well as for understanding prostate cancer progression

Highly Pathogenic Avian Influenza Virus (H5N1) Outbreak in Captive Wild Birds and Cats, Cambodia

From December 2003 through January 2004, the Phnom Tamao Wildlife Rescue Centre, Cambodia, was affected by the highly pathogenic influenza virus (H5N1). Birds from 26 species died. Influenza virus subtype H5N1 was detected in 6 of 7 species tested. Cats from 5 of 7 species were probably infected; none died