A Grouped Hamming Network

A distributed hash table (DHT) is a type of peer-to-peer (P2P) network that, like traditional hash tables, maps keys to values. Unlike traditional hash tables, however, the data is distributed across a network with each node being responsible for a particular range of keys. Numerous other DHTs have been presented and have become the cornerstone of wildly popular P2P file-sharing applications, such as BitTorrent. Each of these DHTs trades-off the number of pointers maintained per node with the overhead and lookup time; storing more pointers decreases the lookup time at the expense of increased overhead. A Grouped Hamming Network (GHN), the overlay network presented in this thesis, allows for the number of pointers per node to be any increasing function of n, P(n) = Ω(log n). The system presented assumes that nodes fail independently and uniformly at random with some probability q = 1 − p. Three different schemes for routing in a GHN are presented. For each routing scheme a theoretical estimate on the probability of failure is given and optimal configurations in terms of n and P(n) are given. Simulations of GHNs with various configurations indicate that the given estimates are indeed accurate for reasonable values of q and that the optimal configurations are accurate

Tetracycline Effects on Candida Albicans Virulence Factors

Object. To determine if tetracycline, previously reported to increase the probability of developing symptomatic vaginal yeast infections, has a direct effect on Candida albicans growth or induction of virulent phenotypes. Method. In vitro, clinical isolates of yeast were cultivated with sublethal concentrations of tetracycline and yeast cell counts, hyphal formation, drug efflux pump activity, biofilm production, and hemolysin production were determined by previously reported methods. Results. Tetracycline concentrations above 150 μg/mL inhibited Candida albicans, but at submicrogram/mL, a modest growth increase during the early hours of the growth curve was observed. Tetracycline did not inhibit hyphal formation at sublethal concentrations. Hypha formation appeared augmented by exposure to tetracycline in the presence of chemically defined medium and especially in the presence of human serum. Efflux pump CDR1 was upregulated and a nonsignificant trend toward increased biofilm formation was noted. Conclusion. Tetracycline appears to have a small growth enhancing effect and may influence virulence through augmentation of hypha formation, and a modest effect on drug efflux and biofilm formation, although tetracycline did not affect hemolysin. It is not clear if the magnitude of the effect is sufficient to attribute vaginitis following tetracycline treatment to direct action of tetracycline on yeast

Anthracite Outdoor Adventure Area (AOAA) Corridor Analysis

This research investigates the potential economic opportunity that is provided to the Shamokin area because of the creation of Anthracite Outdoor Adventure Area (A.O.A.A.). Using spatial analysis, we illustrate travel to the area, commercial mapping and potential accommodation mapping. The exponential growth of A.O.A.A. that has been seen so far illustrates the necessity to rethink commercial zoning in the future, and although there are plans for hotels and future investors, we argue to maximize economic and social benefit to the Northumberland county area, it is necessary to address those challenges and create short-term solutions to bring as much economic prosperity as possible. The research addresses four core goals: 1. Better understand the A.O.A.A. and how it relates to the surrounding area 2. Visually depict where people are traveling from and how they’re getting to the A.O.A.A. during different times of year 3. Research possible solutions to A.O.A.A. obstacles including: understanding visitor transportation routes, parking alternatives, overnight accommodations, better integration between visitors, Shamokin residents, and the A.O.A.A. and visually depict the expansion of the commercial zone of Shamokin. 4. Create maps and a proposal that A.O.A.A. can share with potential investors and people interested in a summary of this information. This report is the result of a student group project for Geography 326 Thinking Space taught by Prof. Vanessa Massaro. The GIS component of the project was part of work for Geography 204 Applied Geography taught by Prof. Duane Griffin

The Role of Notch3 in Self-Renewal of Adipose Derived Stem Cells

Hannah Logan is an undergraduate student in Biology at Louisiana Tech University. Avery Bryan is an undergraduate student in Biology at Louisiana Tech University. Mengcheng Liu is a graduate student in Biology at Louisiana Tech University. Jamie Newman is an Assistant Professor in Biological Sciences at Louisiana Tech University

The Role of NOTCH3 in Determining Adipose Derived Stem Cell Fate

Jacob Cambre, Hannah Logan, Avery Bryan, and Demi Sandel are undergraduate students in Biology at Louisiana Tech University. Mengcheng Liu and Ngozi Ogbonnaya are graduate students in Biology at Louisiana Tech University. Jamie Newman is a Professor in Biological Sciences at Louisiana Tech University

Field responsive mechanical metamaterials.

Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs

Structural Basis for α-Conotoxin Potency and Selectivity

Parkinson\u27s disease is a debilitating movement disorder characterized by altered levels of α6β2* nicotinic acetylcholine receptors (nAChRs) localized on presynaptic striatal catecholaminergic neurons. α-Conotoxin MII (α-CTx MII) is a highly useful ligand to probe α6ß2 nAChRs structure and function, but it does not discriminate among closely related α6* nAChR subtypes. Modification of the α-CTx MII primary sequence led to the identification of α-CTx MII[E11A], an analog with 500-5300 fold discrimination between α6* subtypes found in both human and non-human primates. α-CTx MII[E11A] binds most strongly (femtomolar dissociation constant) to the high affinity α6* nAChR, a subtype that is selectively lost in Parkinson\u27s disease. Here we present the three-dimensional solution structure for α-CTx MII[E11A] as determined by two-dimensional 1H NMR spectroscopy to 0.13 +/- 0.09 Ǻ backbone and 0.45 +/- 0.08 Ǻ heavy atom root mean square deviation from mean structure. Structural comparisons suggest that the increased hydrophobic area of α-CTx MII[E11A] relative to other members of the α-CTx family may be responsible for its exceptionally high affinity for α6α4β2* nAChR as well as discrimination between α6ß2 and α3β2 containing nAChRs. This finding may enable the rational design of novel peptide analogs that demonstrate enhanced specificity for α6* nAChR subunit interfaces and provide a means to better understand nAChR structural determinants that modulate brain dopamine levels and the pathophysiology of Parkinson\u27s disease

Impact of acamprosate on plasma amyloid-β precursor protein in youth: a pilot analysis in fragile X syndrome-associated and idiopathic autism spectrum disorder suggests a pharmacodynamic protein marker

BACKGROUND: Understanding of the pathophysiology of autism spectrum disorder (ASD) remains limited. Brain overgrowth has been hypothesized to be associated with the development of ASD. A derivative of amyloid-β precursor protein (APP), secreted APPα (sAPPα), has neuroproliferative effects and has been shown to be elevated in the plasma of persons with ASD compared to control subjects. Reduction in sAPPα holds promise as a novel molecular target of treatment in ASD. Research into the neurochemistry of ASD has repeatedly implicated excessive glutamatergic and deficient GABAergic neurotransmission in the disorder. With this in mind, acamprosate, a novel modulator of glutamate and GABA function, has been studied in ASD. No data is available on the impact of glutamate or GABA modulation on sAPPα function. METHODS: Plasma APP derivative levels pre- and post-treatment with acamprosate were determined in two pilot studies involving youth with idiopathic and fragile X syndrome (FXS)-associated ASD. We additionally compared baseline APP derivative levels between youth with FXS-associated or idiopathic ASD. RESULTS: Acamprosate use was associated with a significant reduction in plasma sAPP(total) and sAPPα levels but no change occurred in Aβ40 or Aβ42 levels in 15 youth with ASD (mean age: 11.1 years). Youth with FXS-associated ASD (n = 12) showed increased sAPPα processing compared to age-, gender- and IQ-match youth with idiopathic ASD (n = 11). CONCLUSIONS: Plasma APP derivative analysis holds promise as a potential biomarker for use in ASD targeted treatment. Reduction in sAPP (total) and sAPPα may be a novel pharmacodynamic property of acamprosate. Future study is required to address limitations of the current study to determine if baseline APP derivative analysis may predict subgroups of persons with idiopathic or FXS-associated ASD who may respond best to acamprosate or to potentially other modulators of glutamate and/or GABA neurotransmission

Interpretation of TOMS observations of tropical tropospheric ozone with a global model and in-situ observations

We interpret the distribution of tropical tropospheric ozone columns (TTOCs) from the Total Ozone Mapping Spectrometer (TOMS) by using a global three-dimensional model of tropospheric chemistry (GEOS-CHEM) and additional information from in situ observations. The GEOS-CHEM TTOCs capture 44% of the variance of monthly mean TOMS TTOCs from the convective cloud differential method (CCD) with no global bias. Major discrepancies are found over northern Africa and south Asia where the TOMS TTOCs do not capture the seasonal enhancements from biomass burning found in the model and in aircraft observations. A characteristic feature of these northern tropical enhancements, in contrast to southern tropical enhancements, is that they are driven by the lower troposphere where the sensitivity of TOMS is poor due to Rayleigh scattering. We develop an efficiency correction to the TOMS retrieval algorithm that accounts for the variability of ozone in the lower troposphere. This efficiency correction increases TTOCs over biomass burning regions by 3–5 Dobson units (DU) and decreases them by 2–5 DU over oceanic regions, improving the agreement between CCD TTOCs and in situ observations. Applying the correction to CCD TTOCs reduces by ∼5 DU the magnitude of the “tropical Atlantic paradox” [Thompson et al., 2000], i.e. the presence of a TTOC enhancement over the southern tropical Atlantic during the northern African biomass burning season in December–February. We reproduce the remainder of the paradox in the model and explain it by the combination of upper tropospheric ozone production from lightning NOx, persistent subsidence over the southern tropical Atlantic as part of the Walker circulation, and cross-equatorial transport of upper tropospheric ozone from northern midlatitudes in the African “westerly duct.” These processes in the model can also account for the observed 13–17 DU persistent wave-1 pattern in TTOCs with a maximum over the tropical Atlantic and a minimum over the tropical Pacific during all seasons. The photochemical effects of mineral dust have only a minor role on the modeled distribution of TTOCs, including over northern Africa, due to multiple competing effects. The photochemical effects of mineral dust globally decrease annual mean OH concentrations by 9%. A global lightning NOx source of 6 Tg N yr−1 in the model produces a simulation that is most consistent with TOMS and in situ observations

A tropospheric ozone maximum over the Middle East

The GEOS-CHEM global 3-D model of tropospheric chemistry predicts a summertime O3 maximum over the Middle East, with mean mixing ratios in the middle and upper troposphere in excess of 80 ppbv. This model feature is consistent with the few observations from commercial aircraft in the region. Its origin in the model reflects a complex interplay of dynamical and chemical factors, and of anthropogenic and natural influences. The anticyclonic circulation in the middle and upper troposphere over the Middle East funnels northern midlatitude pollution transported in the westerly subtropical jet as well as lightning outflow from the Indian monsoon and pollution from eastern Asia transported in an easterly tropical jet. Large-scale subsidence over the region takes place with continued net production of O3 and little mid-level outflow. Transport from the stratosphere does not contribute significantly to the O3 maximum. Sensitivity simulations with anthropogenic or lightning emissions shut off indicate decreases of 20–30% and 10–15% respectively in the tropospheric O3 column over the Middle East. More observations in this region are needed to confirm the presence of the O3 maximum