Hypergraph Acyclicity and Propositional Model Counting

We show that the propositional model counting problem #SAT for CNF- formulas with hypergraphs that allow a disjoint branches decomposition can be solved in polynomial time. We show that this class of hypergraphs is incomparable to hypergraphs of bounded incidence cliquewidth which were the biggest class of hypergraphs for which #SAT was known to be solvable in polynomial time so far. Furthermore, we present a polynomial time algorithm that computes a disjoint branches decomposition of a given hypergraph if it exists and rejects otherwise. Finally, we show that some slight extensions of the class of hypergraphs with disjoint branches decompositions lead to intractable #SAT, leaving open how to generalize the counting result of this paper

Parameterized Compilation Lower Bounds for Restricted CNF-formulas

We show unconditional parameterized lower bounds in the area of knowledge compilation, more specifically on the size of circuits in decomposable negation normal form (DNNF) that encode CNF-formulas restricted by several graph width measures. In particular, we show that - there are CNF formulas of size $n$ and modular incidence treewidth $k$ whose smallest DNNF-encoding has size $n^{\Omega(k)}$, and - there are CNF formulas of size $n$ and incidence neighborhood diversity $k$ whose smallest DNNF-encoding has size $n^{\Omega(\sqrt{k})}$. These results complement recent upper bounds for compiling CNF into DNNF and strengthen---quantitatively and qualitatively---known conditional low\-er bounds for cliquewidth. Moreover, they show that, unlike for many graph problems, the parameters considered here behave significantly differently from treewidth

The Range of Topological Effects on Communication

We continue the study of communication cost of computing functions when inputs are distributed among $k$ processors, each of which is located at one vertex of a network/graph called a terminal. Every other node of the network also has a processor, with no input. The communication is point-to-point and the cost is the total number of bits exchanged by the protocol, in the worst case, on all edges. Chattopadhyay, Radhakrishnan and Rudra (FOCS'14) recently initiated a study of the effect of topology of the network on the total communication cost using tools from $L_1$ embeddings. Their techniques provided tight bounds for simple functions like Element-Distinctness (ED), which depend on the 1-median of the graph. This work addresses two other kinds of natural functions. We show that for a large class of natural functions like Set-Disjointness the communication cost is essentially $n$ times the cost of the optimal Steiner tree connecting the terminals. Further, we show for natural composed functions like $\text{ED} \circ \text{XOR}$ and $\text{XOR} \circ \text{ED}$, the naive protocols suggested by their definition is optimal for general networks. Interestingly, the bounds for these functions depend on more involved topological parameters that are a combination of Steiner tree and 1-median costs. To obtain our results, we use some new tools in addition to ones used in Chattopadhyay et. al. These include (i) viewing the communication constraints via a linear program; (ii) using tools from the theory of tree embeddings to prove topology sensitive direct sum results that handle the case of composed functions and (iii) representing the communication constraints of certain problems as a family of collection of multiway cuts, where each multiway cut simulates the hardness of computing the function on the star topology

Behavioral and Environmental Residential Risk Factors for Lyme Disease in the Southern Tier of New York

During the past 40 years, Lyme disease has emerged as the most widely reported vector-borne illness in the U.S., with the majority of cases occurring in the Northeastern United States. The pathogenic bacterium Borrelia burgdorferi relies on the deer tick, Ixodes scapularis, the primary enzootic vector responsible for the passage of the bacteria to humans. Behavioral risk factors for tick-borne diseases include those that increase the likelihood of being bit by a tick, including contact with vegetation, exposed skin, and spending time outdoors, all of which can occur within one’s residential yard. Risk factors within the assumed safety net of the home have not been extensively studied, nor has the effects of pet ownership, nor the presence of wild animals within the yard. During 2019-2020 we conducted 130 surveys of households in Broome and Chenango Counties, and performed tick drags in the rear yards of 102 of these homes. Risk factors included household members’ time spent in yard, type of outside activity, use of tick control methods, seasonal activity, and pet ownership, as well as specifics of the yard, including amount and type of vegetation and presence of wild animals. The household’s history of tick bites and infection were also recorded. A risk analysis is currently underway to determine which factors contribute to a higher risk of contracting tick-borne illnesses. This study is part of our ongoing effort to understand the threat of tick-borne diseases in peri-urban and urban settings within the Southern Tier of New York.https://orb.binghamton.edu/research_days_posters_2022/1034/thumbnail.jp

URBAN GEOCHEMICAL STUDIES IN EUROPE

Urban soil is generally contaminated to a variable degree depending on its proximity to contamination sources. Traffic is one of the main sources of urban contamination; lead (Pb) from the use of leaded petrol, zinc (Zn) and cadmium (Cd) from tyre wear, antimony (Sb) from break pads, and the platinum group Nelements (PGEs) from the wear of catalytic converters, are some typical elements that often reach high concentrations in the urban environment. Lead was also a key ingredient in white paint, and in towns with a high proportion of white wooden houses very high concentrations were found in soil. Crematoria can or have emitted mercury (Hg). Coal and heavy oil fired municipal power and heating stations emit sulphur (S), silver (Ag), vanadium (V), bromine (Br) and barium (Ba). The use of impregnated wood may have resulted in high concentrations of arsenic (As), especially in kindergartens (nursery schools) and playgrounds. Building materials (plaster and paint) may also contain high concentrations of organic contaminants, especially polychlorinated biphenyls (PCBs), which again end up in urban soil. Coal and wood burning, the use of diesel fuel, and the production of coke, all lead to the emission of polycyclic aromatic hydrocarbons (PAHs). There exist countless other sources of local contamination in towns, and there is thus every reason to be concerned about the quality of the urban environment, and the suitability of soil for sensitive land uses, such as schools, playgrounds, parks and vegetable gardens. Contaminated urban soil may contaminate indoor dust and, therefore, to an increased human exposure to toxic chemicals. Consequently, the distribution of toxic contaminants in urban soil needs to be documented and known by city administration to avoid costly mistakes in land use planning, and further spreading of highly contaminated materials. The EuroGeoSurveys ‘Geochemistry’ Expert Group during the compilation of a proposal to the Directors for a European wide urban geochemistry project, using a harmonised sampling and analytical methodology, it discovered that many urban geochemical studies have been performed in Europe by National Geological Surveys, which are not known to the wider geoscientific community. Since, the results of these studies are directly related to our quality of life, the EuroGeoSurveys ‘Geo-chemistry’ Expert Group decided to publish at least one case study from each country in a book,which will be available in the second half of 2010. A concise description of some of these studies will be given in this paper

Antarctic bdelloid rotifers: diversity, endemism and evolution

Antarctica is an isolated continent whose conditions challenge the survival of living organisms. High levels of endemism are now known in many Antarctic organisms, including algae, tardigrades, nematodes and microarthropods. Bdelloid rotifers are a key, widespread and abundant group of Antarctic microscopic invertebrates. However, their diversity, regional distribution and endemism have received little attention until recently. We provide the first authoritative review on Antarctic Bdelloidea, based on published data and new collections. Our analysis reveals the extreme levels of bdelloid endemism in Antarctica. Sixty-six bdelloid morphospecies are now confirmed from the continent, and 83–91 putative species are identified using molecular approaches (depending on the delimitation method used). Twelve previously unknown species are described based on both morphology and molecular analyses. Molecular analyses indicate that only two putative species found in Antarctica proved to be truly cosmopolitan. The level of endemism based on the available data set (95%) is higher than that in any other continent, with many bdelloid species occurring only in maritime or continental Antarctica. These findings are consistent with the long-term presence of Bdelloidea in Antarctica, with their considerable isolation facilitating intraregional radiation, providing further evidence that does not support the microbial global ubiquity hypothesis that “everything is everywhere.

Flow and Tableting Behaviors of Some Egyptian Kaolin Powders as Potential Pharmaceutical Excipients

The present work aimed at assessing the pharmaceutical tableting properties of some Egyptian kaolin samples belong to the Abu Zenima kaolin deposits (estimated at 120 million tons). Four representative samples were selected based on kaolinite richness and their structural order-disorder degree, and after purification, they were dried at 70 ºC and heated from room temperature up to 400 ºC (10 ºC/min). Mineralogy, micromorphology, microtexture, granulometry, porosimetry, moisture content, bulk and tapped density, direct and indirect flowability, and tableting characteristics are studied. Results indicated that purified kaolin samples were made up of 95–99% kaolinite, <3% illite, 1% quartz and 1% anatase. The powder showed mesoporous character (pore diameters from 2 to 38 nm and total pore volume from 0.064 to 0.136 cm3/g) with dominance of fine nanosized particles (<1 um–10 nm). The powder flow characteristics of both the ordered (Hinckley Index HI > 0.7, crystallite size D001 > 30 nm) and disordered (HI < 0.7, D001 < 30 nm) kaolinite-rich samples have been improved (Hausner ratio between 1.24 and 1.09) as their densities were influenced by thermal treatment (with some observed changes in the kaolinite XRD reflection profiles) and by moisture content (variable between 2.98% and 5.82%). The obtained tablets exhibited hardness between 33 and 44 N only from the dehydrated powders at 400 ºC, with elastic recovery (ER) between 21.74% and 25.61%, ejection stress (ES) between 7.85 and 11.45 MPa and tensile fracture stress (TFS) between 1.85 and 2.32 MPa, which are strongly correlated with crystallinity (HI) and flowability (HR) parameters. These findings on quality indicators showed the promising pharmaceutical tabletability of the studied Egyptian kaolin powders and the optimization factors for their manufacturability and compactability.This work has been funded by the Egyptian Cultural Affairs and Missions Sector (Plan 2013–2014), Ministry of Higher Education, in collaboration with the Group CTS-946 (Junta de Andalucía) and MINECO project CGL2016-80833-R (Spain), and the grant funded by Erasmus+ KA1 mobility program 2016/2017