Showing papers by "Illinois Institute of Technology published in 2003"

Genome sequence of Bacillus cereus and comparative analysis with Bacillus anthracis

Abstract: Bacillus cereus is an opportunistic pathogen causing food poisoning manifested by diarrhoeal or emetic syndromes1. It is closely related to the animal and human pathogen Bacillus anthracis and the insect pathogen Bacillus thuringiensis, the former being used as a biological weapon and the latter as a pesticide. B. anthracis and B. thuringiensis are readily distinguished from B. cereus by the presence of plasmid-borne specific toxins (B. anthracis and B. thuringiensis) and capsule (B. anthracis). But phylogenetic studies based on the analysis of chromosomal genes bring controversial results, and it is unclear whether B. cereus, B. anthracis and B. thuringiensis are varieties of the same species2 or different species3,4. Here we report the sequencing and analysis of the type strain B. cereus ATCC 14579. The complete genome sequence of B. cereus ATCC 14579 together with the gapped genome of B. anthracis A20125 enables us to perform comparative analysis, and hence to identify the genes that are conserved between B. cereus and B. anthracis, and the genes that are unique for each species. We use the former to clarify the phylogeny of the cereus group, and the latter to determine plasmid-independent species-specific markers.

Spreading of nanofluids on solids

Abstract: Suspensions of nanometre-sized particles (nanofluids) are used in a variety of technological contexts. For example, their spreading and adhesion behaviour on solid surfaces can yield materials with desirable structural and optical properties1. Similarly, the spreading behaviour of nanofluids containing surfactant micelles has implications for soil remediation, oily soil removal, lubrication and enhanced oil recovery. But the well-established concepts of spreading and adhesion of simple liquids do not apply to nanofluids2,3,4,5,6,7. Theoretical investigations have suggested that a solid-like ordering of suspended spheres will occur in the confined three-phase contact region at the edge of the spreading fluid, becoming more disordered and fluid-like towards the bulk phase8,9. Calculations have also suggested that the pressure arising from such colloidal ordering in the confined region will enhance the spreading behaviour of nanofluids10,11. Here we use video microscopy to demonstrate both the two-dimensional crystal-like ordering of charged nanometre-sized polystyrene spheres in water, and the enhanced spreading dynamics of a micellar fluid, at the three-phase contact region. Our findings suggest a new mechanism for oily soil removal—detergency.

Coverage in wireless ad hoc sensor networks

Abstract: Sensor networks pose a number of challenging conceptual and optimization problems such as location, deployment, and tracking. One of the fundamental problems in sensor networks is the calculation of the coverage. In Meguerdichian et al. (2001), it is assumed that the sensor has uniform sensing ability. We provide efficient distributed algorithms to optimally solve the best-coverage problem raised in the above-mentioned article. In addition, we consider a more general sensing model: the sensing ability diminishes as the distance increases. As energy conservation is a major concern in wireless (or sensor) networks, we also consider how to find an optimum best-coverage-path with the least energy consumption and how to find an optimum best-coverage-path that travels a small distance. In addition, we justify the correctness of the method proposed above that uses the Delaunay triangulation to solve the best coverage problem and show that the search space of the best coverage problem can be confined to the relative neighborhood graph, which can be constructed locally.

Just do it? impact of a science apprenticeship program on high school students' understandings of the nature of science and scientific inquiry

Abstract: The purpose of this study was to explicate the impact of an 8-week science apprenticeship program on a group of high-ability secondary students' understandings of the nature of science and scientific inquiry. Ten volunteers (Grades 10–11) completed a modified version of the Views of Nature of Science, Form B both before and after their apprenticeship to assess their conceptions of key aspects of the nature of science and scientific inquiry. Semistructured exit interviews provided an opportunity for students to describe the nature of their apprenticeship experiences and elaborate on their written questionnaire responses. Semistructured exit interviews were also conducted with the scientists who served as mentors for each of the science apprentices. For the most part, students held conceptions about the nature of science and scientific inquiry that were inconsistent with those described in current reforms. Participating science mentors held strong convictions that their apprentices had learned much about the scientific enterprise in the course of doing the science in their apprenticeship. Although most students did appear to gain knowledge about the processes of scientific inquiry, their conceptions about key aspects of the nature of science remained virtually unchanged. Epistemic demand and reflection appeared to be crucial components in the single case where a participant experienced substantial gains in her understandings of the nature of science and inquiry. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 487–509, 2003

Understandings of the nature of science and decision making on science and technology based issues

Abstract: The purpose of this investigation was to explicate the role of the nature of science in decision making on science and technology based issues and to delineate factors and reasoning associated with these types of decisions. Twenty-one volunteer participants purposively selected from the faculty of geographically diverse universities completed an open-ended questionnaire and follow-up interview designed to assess their decision making on science and technology based issues. Participants were subsequently placed in one of two groups based upon their divergent views of the nature of science as assessed by a second open-ended questionnaire and follow-up interview. Profiles of each group's decision making were then constructed, based on participants' previous responses to the decision making questionnaire and follow-up interviews. Finally, the two groups' decisions, decision influencing factors, and decision making strategies were compared. No differences were found between the decisions of the two groups, despite their disparate views of the nature of science. Participants in both groups based their decisions primarily on personal values, morals/ethics, and social concerns. While all participants considered scientific evidence in their decision making, most did not require absolute “proof,” even though many participants held absolute conceptions of the nature of science. Overall, the nature of science did not figure prominently in either group's decisions. These findings contrast with basic assumptions of current science education reform efforts and call for a re-examination of the goals of nature of science instruction. Developing better decision making skills—even on science and technology based issues—may involve other factors, including more value-based instruction and attention to intellectual/moral development. © 2003 Wiley Periodicals, Inc. Sci Ed87:352–377, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10063

QoS guided min-min heuristic for grid task scheduling

Abstract: Task scheduling is an integrated component of computing With the emergence of Grid and ubiquitous computing, new challenges appear in task scheduling based on properties such as security, quality of service, and lack of central control within distributed administrative domains A Grid task scheduling framework must be able to deal with these issues One of the goals of Grid task scheduling is to achieve high system throughput while matching applications with the available computing resources This matching of resources in a nondeterministically shared heterogeneous environment leads to concerns over Quality of Service (QoS) In this paper a novel QoS guided task scheduling algorithm for Grid computing is introduced The proposed novel algorithm is based on a general adaptive scheduling heuristics that includes QoS guidance The algorithm is evaluated within a simulated Grid environment The experimental results show that the new QoS guided Min-Min heuristic can lead to significant performance gain for a variety of applications The approach is compared with others based on the quality of the prediction formulated by inaccurate information

Multiple-image radiography

Abstract: Conventional radiography produces a single image of an object by measuring the attenuation of an x-ray beam passing through it When imaging weakly absorbing tissues, x-ray attenuation may be a suboptimal signature of diseaserelated information In this paper we describe a new phase-sensitive imaging method, called multiple-image radiography (MIR), which is an improvement on a prior technique called diffraction-enhanced imaging (DEI) This paper elaborates on our initial presentation of the idea in Wernick et al (2002 Proc Int SympBiomedImaging pp 129–32) MIR simultaneously produces several images from a set of measurements made with a single x-ray beam Specifically, MIR yields three images depicting separately the effects of refraction, ultrasmall-angle scatter and attenuation by the object All three images have good contrast, in part because they are virtually immune from degradation due to scatter at higher angles MIR also yields a very comprehensive object description, consisting of the angular intensity spectrum of a transmitted x-ray beam at every image pixel, within a narrow angular range Our experiments are based on data acquired using a synchrotron light source; however, in preparation for more practical implementations using conventional x-ray sources, we develop and evaluate algorithms designed for Poisson noise, which is characteristic of photon-limited imaging The results suggest that MIR is capable of operating at low photon count levels, therefore the method

Localized Delaunay triangulation with application in ad hoc wireless networks

Abstract: Several localized routing protocols guarantee the delivery of the packets when the underlying network topology is a planar graph. Typically, relative neighborhood graph (RING) or Gabriel graph (GG) is used as such planar structure. However, it is well-known that the spanning ratios of these two graphs are not bounded by any constant (even for uniform randomly distributed points). Bose et al. (1999) recently developed a localized routing protocol that guarantees that the distance traveled by the packets is within a constant factor of the minimum if Delaunay triangulation of all wireless nodes is used, in addition, to guarantee the delivery of the packets. However, it is expensive to construct the Delaunay triangulation in a distributed manner. Given a set of wireless nodes, we model the network as a unit-disk graph (UDG), in which a link uv exists only if the distance /spl par/uv/spl par/ is at most the maximum transmission range. In this paper, we present a novel localized networking protocol that constructs a planar 2 5-spanner of UDG, called the localized Delaunay triangulation (LDEL), as network topology. It contains all edges that are both in the unit-disk graph and the Delaunay triangulation of all nodes. The total communication cost of our networking protocol is O(n log n) bits, which is within a constant factor of the optimum to construct any structure in a distributed manner. Our experiments show that the delivery rates of some of the existing localized routing protocols are increased when localized Delaunay triangulation is used instead of several previously proposed topologies. Our simulations also show that the traveled distance of the packets is significantly less when the FACE routing algorithm is applied on LDEL, rather than applied on GG.

Sensors, Chemical Sensors, Electrochemical Sensors, and ECS

Abstract: BCPS Department, Illinois Institute of Technology, Chicago, Illinois 60616, USAThe growing branch of science and technology known as sensors has permeated virtually all professional science and engineeringorganizations. Sensor science generates thousands of new publications each year, in publications ranging from magazines such asPopular Mechanics and Discover to learned journals like the Journal of The Electrochemical Society (JES). The ElectrochemicalSociety ~ECS!, which has declared itself the society for solid state and electrochemical science and technology, and its worldwidemembership, have been vitally instrumental in contributions to both the science and technology underlying sensors. This article isabout a few of the chemical sensors that have evolved, those still now evolving, and the continuing role of ECS in advancementof sensor science and engineering.© 2003 The Electrochemical Society. @DOI: 10.1149/1.1539051# All rights reserved.Available electronically January 13, 2003.

Review of Active Control of Flow-Induced Cavity Resonance

Abstract: A review of active control of flow-induced cavity oscillations is presented. This paper is motivated by two factors. First, the search for solutions to the practical problem of suppressing oscillations caused by flow over open cavities has generated significant interest in this area. Second, cavity oscillation control serves as a model problem in the growing multidisciplinary field of flow control. As such, we attempt to summarize recent activities in this area, with emphasis on experimental implementation of open- and closed-loop control approaches. In addition to describing successes, failures, and outstanding issues relevant to cavity oscillations, we highlight the characteristics of the various actuators, flow sensing and measurement, and control methodologies employed to date in order to emphasize the choices, challenges, and potential of flow control in this and other applications.

Fault tolerant deployment and topology control in wireless networks

Abstract: This paper investigate fault tolerance for wireless ad hoc networks. We consider a large-scale of wireless networks whose nodes are distributed randomly in a unit-area square region. Given n wireless nodes V, each with transmission range rn, the wireless networks are often modeled by graph G(V,rn) in which two nodes are connected if their Euclidean distance is no more than rn.We first consider how the transmission range is related with the number of nodes in a fixed area such that the resulted network can sustain k fault nodes with high probability. We show that, for a unit-area square region, the probability that the network G(V,rn) is (k+1)-connected is at least e-e-α when the transmission radius rn satisfies n π rn2 ≥ ln n + (2k-1) ln ln n -2ln k! + 2α for k>0 and n sufficiently large. This result also applies to mobile networks when the moving of wireless nodes always generates randomly distributed positions. Our simulations show that n should be larger than 500 if k=2 or 3 and α = log n and n should be larger than 2500 if k=2 or 3 and α = log log n.We then present a localized method to control the network topology given a (k+1)-faults tolerant deployment G(V,rn) of wireless nodes such that the resulting topology is still (k+1)-faults tolerant but with O(kn) communication links maintained. We show that the constructed topology is also a length spanner. Here a subgraph H is spanner of graph G, if for any two nodes, the length of the shortest path connecting them in H is no more than a small constant factor of the length of the shortest path connecting them in G.Finally, we conduct some simulations to study the practical transmission range to achieve certain probability of k-connected when n is not large enough.

Compression Heating of Selected Fatty Food Materials during High‐pressure Processing

Abstract: Compression heating of selected fatty and model food materials during high-pressure processing was studied using a specially designed experimental system. Commercially available soybean oil, olive oil, beef fat, chicken fat, and salmon fish were studied at different pressures (150 to 600 MPa) and at different initial temperatures (25 to 70 °C). At an initial temperature of 25 °C, fats and oils showed higher compression heating values (up to 8.7 °C per 100 MPa) compared to 2 to 3 °C per 100 MPa for water. Though the compression heating of water depends on its initial temperature, oils have little or no effect of initial temperature.

Recent progress in neutrino factory and muon collider research within the Muon Collaboration

Abstract: We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end. We summarize the physics that can be done with neutrino factories as well as with intense cold beams of muons. The physics potential of muon colliders is reviewed, both as Higgs factories and compact high-energy lepton colliders. The status and time scale of our research and development effort is reviewed as well as the latest designs in cooling channels including the promise of ring coolers in achieving longitudinal and transverse cooling simultaneously. We detail the efforts being made to mount an international cooling experiment to demonstrate the ionization cooling of muons.

Multiparticle simulation of collapsing volcanic columns and pyroclastic flow

Abstract: [1] A multiparticle thermofluid dynamic model was developed to assess the effect of a range of particle size on the transient two-dimensional behavior of collapsing columns and associated pyroclastic flows. The model accounts for full mechanical and thermal nonequilibrium conditions between a continuous gas phase and N solid particulate phases, each characterized by specific physical parameters and properties. The dynamics of the process were simulated by adopting a large eddy simulation approach able to resolve the large-scale features of the flow and by parametrizing the subgrid gas turbulence. Viscous and interphase effects were expressed in terms of Newtonian stress tensors and gas-particle and particle-particle coefficients, respectively. Numerical simulations were carried out by using different grain-size distributions of the mixture at the vent, constitutive equations, and numerical resolutions. Dispersal dynamics describe the formation of the vertical jet, the column collapse and the building of the pyroclastic fountain, the generation of radially spreading pyroclastic flows, and the development of thermal convective instabilities from the fountain and the flow. The results highlight the importance of the multiparticle formulation of the model and describe several mechanical and thermal nonequilibrium effects. Finer particles tend to follow the hot ascending gas, mainly in the phoenix column and, secondarily, in the convective plume above the fountain. Coarser particles tend to segregate mainly along the ground both in the proximal area close to the crater rim because of the recycling of material from the fountain and in the distal area, because of the loss of radial momentum. As a result, pyroclastic flows were described as formed by a dilute fine-rich suspension current overlying a dense underflow rich in coarse particles from the proximal region of the flow. Nonequilibrium effects between particles of different sizes appear to be controlled by particle-particle collisions in the basal layer of the flow, whereas particle dispersal in the suspension current and ascending plumes is determined by the gas-particle drag. Simulations performed with a different grain-size distribution at the vent indicate that a fine-grained mixture produces a thicker and more mobile current, a larger runout distance, and a greater elutriated mass than the coarse-grained mixture.

Online batch/fed-batch process performance monitoring, quality prediction, and variable-contribution analysis for diagnosis

Abstract: An integrated online multivariate statistical process monitoring (MSPM), quality prediction, and fault diagnosis framework is developed for batch processes. Batch data from I batches, with J process variables measured at K time points generate a three-way array of size I × K × J. Unfolding this three-way array into a two-way matrix of size IK × J by preserving the variable direction is advantageous for developing online MSPM methods because it does not require estimation of future portions of new batches. Two different multiway partial least squares (MPLS) models are developed. The first model (MPLSV) is developed between the data matrix (IK × J) and the local batch time (or an indicator variable) for online MSPM. The second model (MPLSB) is developed between the rearranged data matrix in the batch direction (I × KJ) and the final quality matrix for online prediction of end-of-batch quality. The problem of discontinuity in process variable measurements due to operation switching (or moving to a different ...

A model for intracortical visual prosthesis research.

Abstract: In the field of visual prosthesis research, it has generally been held that animal models are limited to testing the safety of implantable hardware due to the inability of the animal to provide a linguistic report of perceptions. In contrast, vision scientists make extensive use of trained animal models to investigate the links between visual stimuli, neural activities, and perception. We describe an animal model for cortical visual prosthesis research in which novel animal psychophysical testing has been employed to compensate for the lack of a linguistic report. One hundred and fifty-two intracortical microelectrodes were chronically implanted in area V1 of a male macaque. Receptive field mapping was combined with eye-tracking to develop a reward-based training procedure. The animal was trained to use electrically induced point-flash percepts, called phosphenes, in performing a memory saccade task. It is our long-term goal to use this animal model to investigate stimulation strategies in developing a multichannel sensory cortical interface.

Morphogenesis of Bacillus Spore Surfaces

Abstract: Spores produced by bacilli are encased in a proteinaceous multilayered coat and, in some species (including Bacillus anthracis), further surrounded by a glycoprotein-containing exosporium. To characterize bacillus spore surface morphology and to identify proteins that direct formation of coat surface features, we used atomic-force microscopy (AFM) to image the surfaces of wild-type and mutant spores of Bacillus subtilis, as well as the spore surfaces of Bacillus cereus 569 and the Sterne strain of Bacillus anthracis. This analysis revealed that the coat surfaces in these strains are populated by a series of bumps ranging between 7 and 40 nm in diameter, depending on the species. Furthermore, a series of ridges encircled the spore, most of which were oriented along the long axis of the spore. The structures of these ridges differ sufficiently between species to permit species-specific identification. We propose that ridges are formed early in spore formation, when the spore volume likely decreases, and that when the spore swells during germination the ridges unfold. AFM analysis of a set of B. subtilis coat protein gene mutants revealed three coat proteins with roles in coat surface morphology: CotA, CotB, and CotE. Our data indicate novel roles for CotA and CotB in ridge pattern formation. Taken together, these results are consistent with the view that the coat is not inert. Rather, the coat is a dynamic structure that accommodates changes in spore volume.

Style mining of electronic messages for multiple authorship discrimination: first results

Abstract: This paper considers the use of computational stylistics for performing authorship attribution of electronic messages, addressing categorization problems with as many as 20 different classes (authors). Effective stylistic characterization of text is potentially useful for a variety of tasks, as language style contains cues regarding the authorship, purpose, and mood of the text, all of which would be useful adjuncts to information retrieval or knowledge-management tasks. We focus here on the problem of determining the author of an anonymous message, based only on the message text. Several multiclass variants of the Winnow algorithm were applied to a vector representation of the message texts to learn models for discriminating different authors. We present results comparing the classification accuracy of the different approaches. The results show that stylistic models can be accurately learned to determine an author's identity.

Network Lifetime and Power Assignment in ad hoc Wireless Networks

Abstract: Used for topology control in ad-hoc wireless networks, Power Assignment is a family of problems, each defined by a certain connectivity constraint (such as strong connectivity) The input consists of a directed complete weighted graph G=(V,c). The power of a vertex u in a directed spanning subgraph H is given by PH (u) = max uv ∈ E(H) c(uv). The power of H is given by \(p(H) = \sum_{u \in v}p{\sc H}(u)\), Power Assignment seeks to minimize p(H) while H satisfies the given connectivity constraint. We present asymptotically optimal O(log n)-approximation algorithms for three Power Assignment problems: Min-Power Strong Connectivity, Min-Power Symmetric Connectivity (the undirected graph having an edge uv iff H has both uv and vu must be connected) and Min-Power Broadcast (the input also has r ∈ V , and H must be a r-rooted outgoing spanning arborescence).

Photonic approach to making a material with a negative index of refraction

Abstract: An approach to producing a composite material with negative refraction index is demonstrated. It is shown that a photonic structure consisting of two dielectric materials, with positive and negative dielectric permittivities, can support electromagnetic surface waves which exhibit the unusual electromagnetic property of left handedness (or negative refraction index). Depending on the dielectric materials, these surface waves localized at the dielectric interfaces can be either surface plasmons or phonons. The detailed geometry of the structure determines whether this composite left-handed material is isotropic or anisotropic.

Science teachers' diagnosis and understanding of students' preconceptions

Abstract: Research has established that students enter their science classes with ideas about the natural world that do not align with accepted scientificbeliefs. The diagnosis of these student preconceptions may be seen as aninitial, crucial step in the process of teacher-facilitated conceptualchange. So as to capture what science teachers do in their everydayclassroom routines to diagnose these student preconceptions, in-depthobservations and interviews were conducted with four exemplary secondaryscience teachers. The teachers' strategies for diagnosing students' preconceptions, their use of information found through diagnosis, and the teachers' understanding of students' preinstructional ideas were all analyzed. The four teachers in this study did not use any formal assessment tools such as pretests, concept maps, interviews, or journal writing to diagnose students' ideas, although they all stated that finding out what students know prior to instruction is important. The teachers all declared that they used questioning to gather information on student ideas but were seen in their classes to rely heavily on low-level, recall questions. One of the teachers, the most experienced, did conduct class discussions where the students were encouraged to express their ideas and preconceptions. The four teachers' understanding of what student preconceptions consist of and the justification for attempting to diagnose these ideas was seen to be weak.The implications of these findings and recommendations for teacher trainingare made in the article. © 2003 Wiley Periodicals, Inc. Sci Ed87:849–867, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10092

Localized construction of bounded degree and planar spanner for wireless ad hoc networks

Abstract: We propose a novel localized algorithm that constructs a bounded degree and planar spanner for wireless ad hoc networks modeled by unit disk graph (UDG). Every node only has to know its 2-hop neighbors to find the edges in this new structure. Our method applies the Yao structure on the local Delaunay graph [21] in an ordering that are computed locally. This new structure has the following attractive properties: (1) it is a planar graph; (2) its node degree is bounded from above by a positive constant 19 + 2p/a (3) it is a t-spanner (given any two nodes u and v, there is a path connecting them in the structure such that its length is no more than t = max(p/2, psina/2 +1) Cdel times of the shortest path in UDG); (4) it can be constructed locally and is easy to maintain when the nodes move around; (5) moreover, we show that the total communication cost is O(n), where n is the number of wireless nodes, and the computation cost of each node is at most O(d log d), where d is its 2-hop neighbors in the original unit disk graph. Here Cdel is the spanning ratio of the Delaunay triangulation, which is at most 4 v3/9 p. And the adjustable parameter a satisfies 0

Troponin I in the murine myocardium: influence on length‐dependent activation and interfilament spacing

Abstract: Cyclic AMP-dependent protein kinase (PKA) targets contractile proteins, troponin-I (TnI) and myosin binding protein C (MyBP-C) in the heart and induces a decrease in myofilament Ca2+ sensitivity. Yet, the effect of sarcomere length (SL) change on Ca2+ sensitivity (length-dependent activation: LDA) following PKA-dependent phosphorylation is not clear. To clarify the role of PKA-dependent phosphorylation of TnI and MyBP-C on LDA in the heart, we examined LDA in skinned myocytes from a non-transgenic (NTG) and a transgenic murine model in which the native cardiac isoform (cTnI) was completely replaced by the slow skeletal isoform of TnI (ssTnI-TG) lacking the phosphorylation sites for PKA, while retaining PKA sites on MyBP-C. In NTG myocytes, PKA treatment decreased Ca2+ sensitivity at each SL, but enhanced the impact of SL change on Ca2+ sensitivity. Despite a greater sensitivity to Ca2+ and a reduction in LDA, neither Ca2+ responsiveness nor LDA was affected by PKA treatment in ssTnI-TG myocytes. To determine whether the above observations could be explained by the lateral separation between thick and thin filaments, as suggested by others, we measured interfilament spacing by X-ray diffraction as a function of SL in skinned cardiac trabeculae in the passive state from both NTG and ssTnI-TG models before and following treatment with PKA. Phosphorylation by PKA increased lattice spacing at every SL in NTG trabeculae. However, the relationship between SL and myofilament lattice spacing in ssTnI-TG was markedly shifted downward to an overall decreased myofilament lattice spacing following PKA treatment. We conclude: (1) PKA-dependent phosphorylation enhances length-dependent activation in NTG hearts; (2) replacement of native TnI with ssTnI increases Ca2+ sensitivity of tension but reduces length-dependent activation; (3) MyBP-C phosphorylation by PKA does not alter calcium responsiveness and induces a decrease in myofilament lattice spacing at all sarcomere lengths and (4) length-dependent activation in the heart cannot be entirely explained by alterations in myofilament lattice spacing.