bluuebunny/crossref_metadata_2025 huggingface dataset:
Chironomid (Diptera) distribution and diversity in Tibetan streams with different glacial influence
Authors: HAMERLÍK LADISLAV , JACOBSEN DEAN
Published: September 2011

Abstract.  1. We collected chironomid larvae and measured basic environmental variables in eight high mountain streams with different degrees of glacial influence in southern Tibet.

2. In total, 32 chironomid taxa were collected. The Orthocladiinae subfamily dominated both in taxon number and in abundance.

3. Both average taxon number and abundance were lower in glacier‐fed streams compared with those of non‐glacial origin. The total taxon number collected (γ diversity) was similar regardless of glacial influence. However, spot diversity (α diversity) was higher in non‐glacial streams, while glacier‐fed streams supported higher species turnover (β diversity).

4. Detrended correspondence analysis scattered the study sites along the first ordination axis, representing a combination of distance from glacier and channel stability. Two‐way indicator analysis distinguished three groups of sites. Group 1 represented the sites closest to the glacier and were characterised by unstable channel conditions and low temperature with characteristic taxa Diamesa sp. 1, Orthocladius (Eud.) sp. and Rheocricotopus sp. Group 2 was made up of glacier‐fed streams situated further from glaciers, with unstable channels and characterised by Orthocladius (Euo.) sp. Group 3 contained non‐glacial streams as well as a glacier‐fed stream further from the glacier margin. For these sites, stable channels and high conductivity were characteristic and Cricotopus (C.) sp., Pseudosmittia sp, Polypedilum sp., Eukiefferiella gracei group and Pagastia sp. 1 were the dominating taxa.

5. We propose a general distribution pattern of chironomids in the streams of glacial and non‐glacial influence in Tibet, which is in accordance with the model proposed by Milner et al. (2001a) Freshwater Biology, 46, 1833–1847.
Energy Conservative Dissipative Particle Dynamics Simulation of Natural Convection in Liquids
Authors: Abu-Nada Eiyad
Published: September 2011

Dissipative particle dynamics with energy conservation (eDPD) was used to study natural convection in liquid domain over a wide range of Rayleigh Numbers. The problem selected for this study was the Rayleigh–Bénard convection problem. The Prandtl number used resembles water where the Prandtl number is set to Pr = 6.57. The eDPD results were compared to the finite volume solutions, and it was found that the eDPD method calculates the temperature and flow fields throughout the natural convection domains correctly. The eDPD model recovered the basic features of natural convection, such as development of plumes, development of thermal boundary layers, and development of natural convection circulation cells (rolls). The eDPD results were presented by means of temperature isotherms, streamlines, velocity contours, velocity vector plots, and temperature and velocity profiles.
Dry Machining of Carbon Fiber Reinforced Plastic Composite by Rotary Ultrasonic Machining: Effects of Machining Variables
Authors: Cong W. L. , Feng Q. , Pei Z. J. , Deines T. W. , Treadwell C.
Published: September 2011

Rotary ultrasonic machining (RUM) has been used to drill holes in brittle, ductile, and composite materials. However, all these experiments were conducted with help of water or oil based coolant. This paper presents an experimental study on RUM of carbon fiber reinforced plastic (CFRP) composite using cold air as coolant. It reports effects of machining variables (ultrasonic power, spindle speed, and feedrate) on outputs (cutting force, torque, surface roughness, and burning) in RUM of CFRP using vortex-tube (VT) generated cold air as coolant.
Finite Element Analysis of Central Bursting Defects Occurring in Cold Forward Extrusion
Authors: Joun Man-Soo , Kim Min-Cheol , Yoon Duk-Jae , Choi Ho-Joon , Son Yo-Hun
Published: September 2011

An improved approach to simulating the formation of central bursting defects is presented in this paper. The rigid-plastic finite element method and a modified McClintock damage model are employed. An improved node-splitting technique with degenerate element cleaning is proposed. The technique is applied to several cold forward extrusion processes to reveal the effects of reduction of area, die conical angle, and friction on the formation of central bursting defects. A comparison with experimental results and predictions found in the literature shows that the present analysis provides more realistic predictions of the shape of a central bursting defect (i.e., an obtuse V-shape, which is typical).
Investigation on the Effect of SiC Nanoparticles on Cutting Forces for Micro-Milling Magnesium Matrix Composites
Authors: Liu Jian , Li Juan , Ji Yingfeng , Xu Chengying
Published: September 2011

Magnesium Metal Matrix Composites (Mg-MMCs) with nano-sized reinforcements exhibit better mechanical properties comparing to pure Magnesium (Mg) and its alloys. However, it is challenging to improve the machinability of this kind of composites. An analytical cutting force model for the micro-milling process was developed and validated to analyze the micro-machinability of the SiC nanoparticles reinforced Mg-MMCs. This model is different from the previous ones because it encompasses the behaviors of the reinforcement nanoparticles in the three cutting regimes, i.e., shearing, ploughing and elastic recovery. The volume fraction of particles and particle size are considered as two significant factors affecting the cutting forces in this model. The effects of the reinforcement nanoparticles on cutting forces were studied through modeling and experimental validation. The simulated cutting forces show a good agreement with the experimental data. Moreover, it is indicated that the amplitude and profile of cutting forces vary with the reinforcement particle’s volume fraction. This mainly arises from the strengthening effect of SiC nanoparticles.
An Introduction to Dynamical Systems
Authors: Sobie Eric A.
Published: September 2011

Lecture notes, slides, and homework assignments illustrate a strategy for teaching.
Science Signaling
Podcast: 20 September 2011
Authors: Gutkind J. Silvio , VanHook Annalisa M.
Published: September 2011

Activation of the small GTPase Rho downstream of a chemokine receptor is required for metastasis of some breast cancer cells.
Shifting Signals with CXCR7
Authors: Adler Elizabeth M.
Published: September 2011

CXCR7 heterodimerizes with CXCR4, leading to preferential activation of β-arrestin–mediated signaling pathways.
Concentration of Antifungal Agents within Host Cell Membranes: a New Paradigm Governing the Efficacy of Prophylaxis
Authors: Campoli P. , Al Abdallah Q. , Robitaille R. , Solis N. V. , Fielhaber J. A. , Kristof A. S. , Laverdiere M. , Filler S. G. , Sheppard D. C.
Published: September 2011

Posaconazole prophylaxis has proven highly effective in preventing invasive fungal infections, despite relatively low serum concentrations. However, high tissue levels of this agent have been reported in treated patients. We therefore hypothesized that the intracellular levels of antifungal agents are an important factor in determining the success of fungal prophylaxis. To examine the effect of host cell-associated antifungals on the growth of medically important molds, we exposed cells to antifungal agents and removed the extracellular drug prior to infection. Epithelial cells loaded with posaconazole and its parent molecule itraconazole, but not other antifungals, were able to inhibit fungal growth for at least 48 h and were protected from damage caused by infection. Cell-associated posaconazole levels were 40- to 50-fold higher than extracellular levels, and the drug was predominantly detected in cellular membranes. Fungistatic levels of posaconazole persisted within epithelial cells for up to 48 h. Therefore, the concentration of posaconazole in mammalian host cell membranes mediates its efficacy in prophylactic regimens and likely explains the observed discrepancy between serum antifungal levels and efficacy.
Dose of Trimethoprim-Sulfamethoxazole To Treat Skin and Skin Structure Infections Caused by Methicillin-Resistant Staphylococcus aureus
Authors: Cadena Jose , Nair Shalini , Henao-Martinez Andres F. , Jorgensen James H. , Patterson Jan E. , Sreeramoju Pranavi V.
Published: September 2011

We undertook this study to investigate whether treatment with a higher dose of trimethoprim-sulfamethoxazole (TMP/SMX) led to greater clinical resolution in patients with skin and soft tissue infections (SSTIs) caused by methicillin-resistant
Staphylococcus aureus
(MRSA). A prospective, observational cohort with nested case-control study was performed at a public tertiary health system. Among patients with MRSA SSTIs during the period from May 2008 to September 2008 who received oral monotherapy with TMP/SMX and whose clinical outcome was known, the clinical characteristics and outcomes were compared between patients treated with a high dose of TMP/SMX (320 mg/1,600 mg twice daily) for 7 to 15 days and patients treated with the standard dose of TMP/SMX (160 mg/800 mg twice daily) for 7 to 15 days. In patients with MRSA SSTIs, those treated with the high dose of TMP/SMX (
n
= 121) had clinical characteristics similar to those of patients treated with the standard dose of TMP/SMX (
n
= 170). The only exception was a higher proportion of patients with a history of trauma upon admission among the patients treated with the higher dose. The proportion of patients with clinical resolution of infection was not different in the two groups (88/121 [73%] versus 127/170 [75%];
P
= 0.79). The lack of significance remained in patients with abscess upon stratified analysis by whether surgical drainage was performed. The study found that patients with MRSA SSTIs treated with the higher dose of TMP/SMX (320/1,600 mg twice daily) for 7 to 15 days had a similar rate of clinical resolution as patients treated with the standard dose of TMP/SMX (160/800 mg twice daily) for 7 to 15 days.
Molecular Characteristics of KPC-Producing Enterobacteriaceae at the Early Stage of Their Dissemination in Poland, 2008–2009
Authors: Baraniak Anna , Grabowska Anna , Izdebski Radosław , Fiett Janusz , Herda Małgorzata , Bojarska Katarzyna , Żabicka Dorota , Kania-Pudło Marta , Młynarczyk Grażyna , Żak-Puławska Zofia , Hryniewicz Waleria , Gniadkowski Marek ,   the KPC-PL Study Group
Published: September 2011

After the first report in May 2008, the National Reference Center for Susceptibility Testing confirmed 113 cases of infection or colonization by KPC-producing members of the family
Enterobacteriaceae
in Poland by the end of 2009. The vast majority of patients were found in 18 hospitals; three patients were diagnosed at outpatient clinics. Most of the institutions were in the Warsaw area, including three hospitals with the highest numbers of cases. When available, the data on previous hospitalizations often indicated that these hospitals were the probable acquisition sites; one patient arrived from New York. The group of 119 unique isolates consisted of
Klebsiella pneumoniae
(
n
= 114), followed by
Klebsiella oxytoca
(
n
= 3), and
Escherichia coli
(
n
= 2). The
K. pneumoniae
isolates were dominated by the clone sequence type 258 (ST258) (
n
= 111); others were ST11 and ST23. The ST258 group was heterogeneous, with 28 pulsed-field gel electrophoresis (PFGE) subtypes, ∼25 plasmid profiles, and nine β-lactamase patterns differing by KPC variants (KPC-2 mainly), and SHV-12, CTX-M-3, and TEM-1-like enzymes. Plasmids carrying
bla
KPC
genes varied in size (∼48 to 250 kb), structure, and conjugation potential. Transferable IncFII
K
plasmids of ∼110 to 160 kb, probably pKpQIL or its derivatives, were observed in all
K. pneumoniae
clones and in
K. oxytoca
. Also prevalent were nontypeable pETKp50-like plasmids of ∼50 kb, found in
K. pneumoniae
ST258 and
E. coli
isolates (ST93 and ST224). Two
K. pneumoniae-E. coli
pairs from single patients might represent the
in vivo
transfer of such plasmids. The striking diversity of KPC producers at the early stage of dissemination could result from several introductions of these bacteria into the country, their multidirectional evolution during clonal spread, and transfer of the plasmids.
Identification and Characterization of the Anti-Methicillin-Resistant Staphylococcus aureus WAP-8294A2 Biosynthetic Gene Cluster from Lysobacter enzymogenes OH11
Authors: Zhang Wei , Li Yaoyao , Qian Guoliang , Wang Yan , Chen Haotong , Li Yue-Zhong , Liu Fengquan , Shen Yuemao , Du Liangcheng
Published: September 2011

Lysobactor enzymogenes
strain OH11 is an emerging biological control agent of fungal and bacterial diseases. We recently completed its genome sequence and found it contains a large number of gene clusters putatively responsible for the biosynthesis of nonribosomal peptides and polyketides, including the previously identified antifungal dihydromaltophilin (HSAF). One of the gene clusters contains two huge open reading frames, together encoding 12 modules of nonribosomal peptide synthetases (NRPS). Gene disruption of one of the NRPS led to the disappearance of a metabolite produced in the wild type and the elimination of its antibacterial activity. The metabolite and antibacterial activity were also affected by the disruption of some of the flanking genes. We subsequently isolated this metabolite and subjected it to spectroscopic analysis. The mass spectrometry and nuclear magnetic resonance data showed that its chemical structure is identical to WAP-8294A2, a cyclic lipodepsipeptide with potent anti-methicillin-resistant
Staphylococcus aureus
(MRSA) activity and currently in phase I/II clinical trials. The WAP-8294A2 biosynthetic genes had not been described previously. So far, the Gram-positive
Streptomyces
have been the primary source of anti-infectives.
Lysobacter
are Gram-negative soil/water bacteria that are genetically amendable and have not been well exploited. The WAP-8294A2 synthetase represents one of the largest NRPS complexes, consisting of 45 functional domains. The identification of these genes sets the foundation for the study of the WAP-8294A2 biosynthetic mechanism and opens the door for producing new anti-MRSA antibiotics through biosynthetic engineering in this new source of
Lysobacter
.
Genotypic and Phenotypic Variation in Pseudomonas aeruginosa Reveals Signatures of Secondary Infection and Mutator Activity in Certain Cystic Fibrosis Patients with Chronic Lung Infections
Authors: Warren Ashley E. , Boulianne-Larsen Carla M. , Chandler Christine B. , Chiotti Kami , Kroll Evgueny , Miller Scott R. , Taddei Francois , Sermet-Gaudelus Isabelle , Ferroni Agnes , McInnerney Kathleen , Franklin Michael J. , Rosenzweig Frank
Published: September 2011

Evolutionary adaptation ofPseudomonas aeruginosato the cystic fibrosis lung is limited by genetic variation, which depends on rates of horizontal gene transfer and mutation supply. Because each may increase following secondary infection or mutator emergence, we sought to ascertain the incidence of secondary infection and genetic variability in populations containing or lacking mutators. Forty-nine strains collected over 3 years from 16 patients were phenotyped for antibiotic resistance and mutator status and were genotyped by repetitive-sequence PCR (rep-PCR), pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). Though phenotypic and genetic polymorphisms were widespread and clustered more strongly within than between longitudinal series, their distribution revealed instances of secondary infection. Sequence data, however, indicated that interlineage recombination predated initial strain isolation. Mutator series were more likely to be multiply antibiotic resistant, but not necessarily more variable in their nucleotide sequences, than nonmutators. One mutator and one nonmutator series were sequenced at mismatch repair loci and analyzed for gene content using DNA microarrays. Both were wild type with respect tomutL, but mutators carried an 8-bpmutSdeletion causing a frameshift mutation. Both series lacked 126 genes encoding pilins, siderophores, and virulence factors whose inactivation has been linked to adaptation during chronic infection. Mutators exhibited loss of severalfold more genes having functions related to mobile elements, motility, and attachment. A 105-kb, 86-gene deletion was observed in one nonmutator that resulted in loss of virulence factors related to pyoverdine synthesis and elements of the multidrug efflux regulon. Diminished DNA repair activity may facilitate but not be absolutely required for rapid evolutionary change.
Ehrlichia chaffeensis Induces Monocyte Inflammatory Responses through MyD88, ERK, and NF-κB but Not through TRIF, Interleukin-1 Receptor 1 (IL-1R1)/IL-18R1, or Toll-Like Receptors
Authors: Miura Koshiro , Matsuo Junji , Rahman M. Akhlakur , Kumagai Yumi , Li Xin , Rikihisa Yasuko
Published: September 2011

Human monocytic ehrlichiosis, an influenza-like illness accompanied by signs of hepatitis, is caused by infection of monocytes/macrophages with a lipopolysaccharide-deficient bacterium,Ehrlichia chaffeensis. TheE. chaffeensisstrain Wakulla induces diffuse hepatitis with neutrophil infiltration in mice with severe combined immunodeficiency, which is accompanied by strong CXCL2 (mouse functional homolog of interleukin-8 [IL-8]) and tumor necrosis factor alpha (TNF-α) expression in the liver. In this study, we found that expression of IL-1β, CXCL2, and TNF-α was induced by strain Wakulla in mouse bone marrow-derived macrophages; this expression was dependent on MyD88, but not on TRIF, TLR2/4, IL-1R1/IL-18R1, or endosome acidification. When the human leukemia cell line THP-1 was exposed toE. chaffeensis, significant upregulation of IL-8, IL-1β, and TNF-α mRNA and extracellular regulated kinase 2 (ERK2) activation were detected. U0126 (inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 [MEK1/2] upstream of ERK), manumycin A (Ras inhibitor), BAY43-9006 (Raf-1 inhibitor), and NS-50 (inhibitor of NF-κB nuclear translocation) inhibited the cytokine gene expression. A luciferase reporter assay using HEK293 cells, which lack Toll-like receptors (TLRs), showed activation of both the IL-8 promoter and NF-κB byE. chaffeensis. Activation of the IL-8 promoter in transfected HEK293 cells was inhibited by manumycin A, BAY43-9006, U0126, and transfection with a dominant-negative Ras mutant. These results indicate that theE. chaffeensisWakulla strain can induce inflammatory responses through MyD88-dependent NF-κB and ERK pathways, without the involvement of TRIF and TLRs.
A randomised control trial of short term efficacy of in-shoe foot orthoses compared with a wait and see policy for anterior knee pain and the role of foot mobility
Authors: Mills Kathryn , Blanch Peter , Dev Priya , Martin Michael , Vicenzino Bill
Published: September 2011

Objectives

To investigate the short-term clinical efficacy of in-shoe foot orthoses over a wait-and-see policy in the treatment of anterior knee pain (AKP) and evaluate the ability of foot posture measures to predict outcome.

Design

Single-blind, randomised control trial.

Participants

Forty participants (18–40 years) with clinically diagnosed AKP of greater than 6-week duration, who had not been treated with orthoses in the previous 5 years.

Intervention

Prefabricated orthoses perceived as most comfortable from a selection of 3 different hardness values compared with a wait-and-see control group.

Outcome measures

Participant-perceived global improvement, Kujala Patellofemoral Score, usual and worst pain severity over the previous week and the Patient Specific Functional Scale measures at 6 weeks.

Results

Foot orthoses produced a significant global improvement compared with the control group (p = 0.008, relative risk reduction = 8.47%, numbers needed to treat = 2). Significant differences also occurred in measures of function (standardised mean difference = 0.71). Within the intervention group, individuals who exhibited a change in midfoot width from weight bearing to non-weight bearing of >11.25 mm were more likely to report a successful outcome (correct classification 77.8%).

Conclusion

This is the first study to show orthoses provide greater improvements in AKP than a wait-and-see approach. Individuals with greater midfoot mobility are more likely to experience success from treatment.

Trial Registration

ACTRN12611000492954
TRANSIENT MAGNETO-THERMOELASTIC RESPONSE FOR A SEMI-INFINITE BODY WITH VOIDS AND VARIABLE MATERIAL PROPERTIES DURING THERMAL SHOCK
Authors: XIONG QI-LIN , TIAN XIAO-GENG
Published: September 2011

In this work the magneto-thermoelastic problem of a semi-infinite body with voids and temperature-dependent material properties placed in a transverse magnetic field is investigated in the context of different theories of generalized thermoelasticity. The upper surface of the body is subjected to a zonal time-dependent heat shock. The solution is obtained by solving finite element governing equations of the problem. The results, including temperature, stresses, displacements, the change in volume fraction field, induced magnetic field and induced electric field are presented graphically. Comparisons are made in the results obtained under different theories of generalized thermoelasticity and three forms of temperature-dependent material properties (absolute temperature-dependent, reference temperature-dependent, and temperature-independent). Finally the voids effects in the theory of thermoelasticity are presented graphically.
LABORATORY INVESTIGATION OF DIFFERENT EJECTOR GEOMETRIES FOR R-744 TRANSCRITICAL SYSTEMS
Authors: HAFNER ARMIN
Published: September 2011

This work describes measurement results of ejectors manufactured and experimentally investigated at SINTEF Energy Research/NTNU. The ejectors are experimentally investigated in an oil free R-744 test facility in order to focus on the ejector properties and behavior. Five different ejectors were experimentally investigated at equal boundary conditions. The results are promising with pressure lifts close to 9 bars at low mass entrainment ratios of 0.22 and suction pressure ratios of 1.24. At an higher mass entrainment ratio of 0.56 and suction pressure ratio of 1.14 a pressure lift of 6.5 bar was achieved with the smallest mixing section. Best performances were measured with the smallest mixing section diameter (3 mm) and a short nozzle with an ID of 0.9 mm. The results are very promising and show a very good Coefficient of Performance improvement potential for R-744 transcritical process deploying an ejector, as the pressure ratio for a compressor could be reduced by close to 10 bars.
Lightweight monadic programming in ML
Authors: Swamy Nikhil , Guts Nataliya , Leijen Daan , Hicks Michael
Published: September 2011

Many useful programming constructions can be expressed as monads. Examples include probabilistic modeling, functional reactive programming, parsing, and information flow tracking, not to mention effectful functionality like state and I/O. In this paper, we present a type-based rewriting algorithm to make programming with arbitrary monads as easy as using ML's built-in support for state and I/O. Developers write programs using monadic values of type
m
τ as if they were of type τ, and our algorithm inserts the necessary binds, units, and monad-to-monad morphisms so that the program type checks. Our algorithm, based on Jones' qualified types, produces principal types. But principal types are sometimes problematic: the program's semantics could depend on the choice of instantiation when more than one instantiation is valid. In such situations we are able to simplify the types to remove any ambiguity but without adversely affecting typability; thus we can accept strictly more programs. Moreover, we have proved that this simplification is
efficient
(linear in the number of constraints) and
coherent
: while our algorithm induces a particular rewriting, all related rewritings will have the same semantics. We have implemented our approach for a core functional language and applied it successfully to simple examples from the domains listed above, which are used as illustrations throughout the paper.
Forest
Authors: Fisher Kathleen , Foster Nate , Walker David , Zhu Kenny Q.
Published: September 2011

A
filestore
is a structured collection of data files housed in a conventional hierarchical file system. Many applications use filestores as a poor-man's database, and the correct execution of these applications requires that the collection of files, directories, and symbolic links stored on disk satisfy a variety of precise invariants. Moreover, all of these structures must have acceptable ownership, permission, and timestamp attributes. Unfortunately, current programming languages do not provide support for documenting assumptions about filestores, detecting errors in them, or safely loading from and storing to them.

This paper describes the design, implementation, and semantics of Forest, a new domain-specific language for describing filestores. The language uses a type-based metaphor to specify the expected structure, attributes, and invariants of filestores. Forest generates loading and storing functions that make it easy to connect data on disk to an isomorphic representation in memory that can be manipulated as if it were any other data structure. Forest also generates metadata that describes the degree to which the structures on the disk conform to the specification, making error detection easy. In a nutshell, Forest extends the rigorous discipline of typed programming languages to the untyped world of file systems.

We have implemented Forest as an embedded domain-specific language in Haskell. In addition to generating infrastructure for reading, writing and checking file systems, our implementation generates type class instances that make it easy to build generic tools that operate over arbitrary filestores. We illustrate the utility of this infrastructure by building a file system visualizer, a file access checker, a generic query interface, description-directed variants of several standard UNIX shell tools and (circularly) a simple Forest description inference engine. Finally, we formalize a core fragment of Forest in a semantics inspired by classical tree logics and prove round-tripping laws showing that the loading and storing functions behave sensibly.
Modular verification of preemptive OS kernels
Authors: Gotsman Alexey , Yang Hongseok
Published: September 2011

Most major OS kernels today run on multiprocessor systems and are preemptive: it is possible for a process running in the kernel mode to get descheduled. Existing modular techniques for verifying concurrent code are not directly applicable in this setting: they rely on scheduling being implemented correctly, and in a preemptive kernel, the correctness of the scheduler is interdependent with the correctness of the code it schedules. This interdependency is even stronger in mainstream kernels, such as Linux, FreeBSD or XNU, where the scheduler and processes interact in complex ways.

We propose the first logic that is able to decompose the verification of preemptive multiprocessor kernel code into verifying the scheduler and the rest of the kernel separately, even in the presence of complex interdependencies between the two components. The logic hides the manipulation of control by the scheduler when reasoning about preemptable code and soundly inherits proof rules from concurrent separation logic to verify it thread-modularly. This is achieved by establishing a novel form of refinement between an operational semantics of the real machine and an axiomatic semantics of OS processes, where the latter assumes an abstract machine with each process executing on a separate virtual CPU. The refinement is local in the sense that the logic focuses only on the relevant state of the kernel while verifying the scheduler. We illustrate the power of our logic by verifying an example scheduler, modelled on the one from Linux 2.6.11.
Characteristic formulae for the verification of imperative programs
Authors: Charguéraud Arthur
Published: September 2011

In previous work, we introduced an approach to program verification based on characteristic formulae. The approach consists of generating a higher-order logic formula from the source code of a program. This characteristic formula is constructed in such a way that it gives a sound and complete description of the semantics of that program. The formula can thus be exploited in an interactive proof assistant to formally verify that the program satisfies a particular specification.

This previous work was, however, only concerned with purely-functional programs. In the present paper, we describe the generalization of characteristic formulae to an imperative programming language. In this setting, characteristic formulae involve specifications expressed in the style of Separation Logic. They also integrate the frame rule, which enables local reasoning. We have implemented a tool based on characteristic formulae. This tool, called CFML, supports the verification of imperative Caml programs using the Coq proof assistant. Using CFML, we have formally verified nontrivial imperative algorithms, as well as CPS functions, higher-order iterators, and programs involving higher-order stores.
Delay performance of backlog based random access
Authors: Bouman N. , Borst S. C. , van Leeuwaarden J. S.H.
Published: September 2011

Backlog-based CSMA strategies provide a popular mechanism for distributed medium access control in wireless networks. When suitably designed, such strategies offer the striking capability to match the optimal throughput performance of centralized scheduling algorithms in a wide range of scenarios. Unfortunately, however, the activation rules used in these schemes tend to yield excessive backlogs and delays. More aggressive activation rates can potentially improve the delay performance, but may not allow provable maximum-stability guarantees. In order to gain a fundamental understanding how the shape of the activation function affects the queueing behavior, we focus on a single- node scenario, thus separating the impact of the network topology. We demonstrate that three qualitatively different regimes can arise, depending on how rapidly the activation function increases with the backlog. Simulation experiments are conducted to validate the analytical findings.
Improving path failure detection in SCTP using adaptive heartbeat time intervals
Authors: Cano Maria Dolores
Published: September 2011

Path failure detection in the Stream Control Transmission Protocol (SCTP) is a key point to determine its viability as a transport protocol for mobile applications in wireless environments. Whereas most works have focused on how to optimize SCTP failure detection by modifying the retrans-mission algorithm inherited from TCP, we propose to change the SCTP heartbeat mechanism. In our proposal, the heart- beat time interval adapts to network conditions, so the more frequent the path failures are, the faster is the heartbeat pace. By simulation, we show that our approach detects inactive alternative destination addresses earlier, improving significantly the throughput of the SCTP connection.
On the impact of the flow size distribution's tail index on network performance with TCP connections
Authors: Goga Oana , Loiseau Patrick , Gonçalves Paulo
Published: September 2011

In this paper, we study the impact of the flow-size distribution on network performance in the case of a single bottle-neck with finite buffer. To tackle the case where flows are transmitted with the TCP protocol, we use real experiments and ns-2 simulations. Our preliminary results show that the distribution's tail index impacts the performance in a more complex way than what is reported in existing literature. In particular, we exhibit situations where a heavier tail gives better performance for certain metrics. We argue that a main cause of our observed results is the transient behavior at the beginning of each flow.
Load balancing and the power of preventive probing
Authors: Van Houdt B.
Published: September 2011

Consider a randomized load balancing problem consisting of a large number n of server sites each equipped with K servers. Under the greedy policy, clients randomly probe a site to check whether there is still a server available. If not, d -- 1 other sites are probed and the task is assigned to the site with the fewest number of busy servers. If all the servers are also busy in each of these d -- 1 sites, the task is lost.

This short paper analyzes a set of policies, i.e., (L, d) policies, that will occasionally probe additional sites even when there is still a server available at the site that was probed first. Using mean field methods, we show that these policies, that preventively probe other sites, can achieve the same loss probability while requiring a lower overall probe rate.
Repeatability and workability evaluation of SIGMOD 2011
Authors: Bonnet Philippe , Manegold Stefan , Bjørling Matias , Cao Wei , Gonzalez Javier , Granados Joel , Hall Nancy , Idreos Stratos , Ivanova Milena , Johnson Ryan , Koop David , Kraska Tim , Müller René , Olteanu Dan , Papotti Paolo , Reilly Christine , Tsirogiannis Dimitris , Yu Cong , Freire Juliana , Shasha Dennis
Published: September 2011

SIGMOD has offered, since 2008, to verify the experiments published in the papers accepted at the conference. This year, we have been in charge of reproducing the experiments provided by the authors (repeatability), and exploring changes to experiment parameters (workability). In this paper, we assess the SIGMOD repeatability process in terms of participation, review process and results. While the participation is stable in terms of number of submissions, we find this year a sharp contrast between the high participation from Asian authors and the low participation from American authors. We also find that most experiments are distributed as Linux packages accompanied by instructions on how to setup and run the experiments. We are still far from the vision of executable papers.
Polymeric Scaffolds in Tissue Engineering Application: A Review
Authors: Dhandayuthapani Brahatheeswaran , Yoshida Yasuhiko , Maekawa Toru , Kumar D. Sakthi
Published: September 2011

Current strategies of regenerative medicine are focused on the restoration of pathologically altered tissue architectures by transplantation of cells in combination with supportive scaffolds and biomolecules. In recent years, considerable interest has been given to biologically active scaffolds which are based on similar analogs of the extracellular matrix that have induced synthesis of tissues and organs. To restore function or regenerate tissue, a scaffold is necessary that will act as a temporary matrix for cell proliferation and extracellular matrix deposition, with subsequent ingrowth until the tissues are totally restored or regenerated. Scaffolds have been used for tissue engineering such as bone, cartilage, ligament, skin, vascular tissues, neural tissues, and skeletal muscle and as vehicle for the controlled delivery of drugs, proteins, and DNA. Various technologies come together to construct porous scaffolds to regenerate the tissues/organs and also for controlled and targeted release of bioactive agents in tissue engineering applications. In this paper, an overview of the different types of scaffolds with their material properties is discussed. The fabrication technologies for tissue engineering scaffolds, including the basic and conventional techniques to the more recent ones, are tabulated.
Giant Ectopic Ureter Mimicking Pelvic Organ Prolapse: A Case Report
Authors: Simsir Adnan , Kizilay Fuat , Yildiz Bilbasar , Nazli Oktay
Published: September 2011

Ectopic ureter is one of the most common urinary tract anomalies. We, herein, present a case of a giant ureter with ectopic orifice, mimicking pelvic organ prolapse, which is the first in the literature. A 59-year-old female patient presenting with frequently recurrent urinary tract infection had grade 3 pelvic organ prolapse. On examination, the organ producing the appearance of prolapse was found to be a right ureter of giant size and was obstructed by a large stone at the distal segment. The proximal end of the ureter ended blindly. After exploration, the stone was removed, the ureter was detached from the urethra, and the lumen was tied off and cut 5 cm proximally. At 6 months postoperatively, the patient is being followed up without any clinical problems. In such cases with nonfunctioning renal segment draining proximally, the chance of cure can be obtained without a need for a comprehensive intervention such as total abdominal ureterectomy.
Etiology and Viral Genotype in Patients with End-Stage Liver Diseases admitted to a Hepatology Unit in Colombia
Authors: Cortes-Mancera Fabian , Loureiro Carmen Luisa , Hoyos Sergio , Restrepo Juan-Carlos , Correa Gonzalo , Jaramillo Sergio , Norder Helene , Pujol Flor Helene , Navas Maria-Cristina
Published: September 2011

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the principal risk factor associated to end-stage liver diseases in the world. A study was carried out on end-stage liver disease cases admitted to an important hepatology unit in Medellin, the second largest city in Colombia. From 131 patients recruited in this prospective study, 71% of cases were diagnosed as cirrhosis, 12.2% as HCC, and 16.8% as cirrhosis and HCC. Regarding the risk factors of these patients, alcohol consumption was the most frequent (37.4%), followed by viral etiology (17.6%). Blood and/or hepatic tissue samples from patients with serological markers for HCV or HBV infection were characterized; on the basis of the phylogenetic analysis of HCV 5′
UTR and HBV S gene, isolates belonged to HCV/1 and HBV/F3, respectively. These results confirm the presence of strains associated with poor clinical outcome, in patients with liver disease in Colombia; additionally, HBV basal core promoter double mutant was identified in HCC cases. Here we show the first study of cirrhosis and/or HCC in Colombian and HBV and HCV molecular characterization of these patients. Viral aetiology was not the main risk factor in this cohort but alcohol consumption.
Endometrial Histopathology in Patients with Laparoscopic Proven Salpingitis and HIV-1 Infection
Authors: Mugo Nelly R. , Kiehlbauch Julia , Kiviat Nancy , Nguti Rosemary , Gichuhi Joseph W. , Stamm Walter E. , Cohen Craig R.
Published: September 2011

Study Objective. To identify sensitive and specific histological criteria for endometritis in women with laparoscopically-confirmed acute salpingitis.Methods. Women, age 18–40 years of age presenting with complaints of lower abdominal pain ≤2 weeks and no antibiotics use in past two weeks, were enrolled. They underwent clinical examination, screening for HIV; other sexually transmitted infections plus endometrial biopsy sampling for histopathology. Diagnostic laparoscopy confirmed the diagnosis of acute salpingitis. Controls were women undergoing tubal ligation and HIV-1 infected women asymptomatic for genital tract infection.Results. Of 125 women with laparoscopically-confirmed salpingitis, 38% were HIV-1 seropositive. Nineteen HIV-1 negative controls were recruited. For the diagnosis of endometritis, ≥1 plasma cells (PC) and ≥3 polymorphonuclear lymphocytes (PMN) per HPF in the endometrium had a sensitivity of 74% for HIV-1-seropositive, 63% for HIV-1-seronegative women with a specificity of 75% and positive predictive value of 85% regardless of HIV-1-infection for predicting moderate to severe salpingitis. For HIV-1-seronegative women with mild salpingitis, ≥1 PC and ≥3 PMN had a sensitivity of 16% and a PPV of 57%.Conclusion. Endometrial histology, did not perform well as a surrogate marker for moderate to severe salpingitis, and failed as a surrogate marker for mild salpingitis.
Exercise Increases Insulin Content and Basal Secretion in Pancreatic Islets in Type 1 Diabetic Mice
Authors: Huang Han-Hung , Farmer Kevin , Windscheffel Jill , Yost Katie , Power Mary , Wright Douglas E. , Stehno-Bittel Lisa
Published: September 2011

Exercise appears to improve glycemic control for people with type 1 diabetes (T1D). However, the mechanism responsible for this improvement is unknown. We hypothesized that exercise has a direct effect on the insulin-producing islets. Eight-week-old mice were divided into four groups: sedentary diabetic, exercised diabetic, sedentary control, and exercised control. The exercised groups participated in voluntary wheel running for 6 weeks. When compared to the control groups, the islet density, islet diameter, andβ-cell proportion per islet were significantly lower in both sedentary and exercised diabetic groups and these alterations were not improved with exercise. The total insulin content and insulin secretion were significantly lower in sedentary diabetics compared to controls. Exercise significantly improved insulin content and insulin secretion in islets in basal conditions. Thus, some improvements in exercise-induced glycemic control in T1D mice may be due to enhancement of insulin content and secretion in islets.
LysoPC and PAF Trigger Arachidonic Acid Release by Divergent Signaling Mechanisms in Monocytes
Authors: Oestvang Janne , Anthonsen Marit W. , Johansen Berit
Published: September 2011

Oxidized low-density lipoproteins (LDLs) play an important role during the development of atherosclerosis characterized by intimal inflammation and macrophage accumulation. A key component of LDL is lysophosphatidylcholine (lysoPC). LysoPC is a strong proinflammatory mediator, and its mechanism is uncertain, but it has been suggested to be mediated via the platelet activating factor (PAF) receptor. Here, we report that PAF triggers a pertussis toxin- (PTX-) sensitive intracellular signaling pathway leading to sequential activation of sPLA2, PLD, cPLA2, and AA release in human-derived monocytes. In contrast, lysoPC initiates two signaling pathways, one sequentially activating PLD and cPLA2, and a second parallel PTX-sensitive pathway activating cPLA2with concomitant activation of sPLA2, all leading to AA release. In conclusion, lysoPC and PAF stimulate AA release by divergent pathways suggesting involvement of independent receptors. Elucidation of monocyte lysoPC-specific signaling mechanisms will aid in the development of novel strategies for atherosclerosis prevention, diagnosis, and therapy.
Synthesis and Structural Investigations of Ag‐Added BaTiO3‐CuO Mixed Oxide for CO2 Gas Sensing
Authors: El-Sayed Ahmed Mohamed , Ismail Fathy Mohamed , Yakout Saad Mabrouk
Published: September 2011

Compositions having the general formula BaTiO3‐CuO + x wt% Ag, where x = 0, 1, 1.5, and 2 have been prepared by solid state ceramic processing and sintered at 500 and 700∘C for 5 h. Thermogravimetric analysis (TGA), X‐ray powder diffraction (XRD), infrared absorption spectra (IR), and scanning electron microscopy (SEM) were used to characterize the obtained sensor pellets. It was found that no solid state reaction took place between BaTiO3 and CuO during sintering process. The sensitivity of the prepared sensors to CO2 gas increases with increasing sintering temperature and Ag content. The correlation between Ag content at different sintering temperature and structure characterization is discussed.
Effects of Mushroom and Chicory Extracts on the Physiology and Shape of Prevotella intermedia, a Periodontopathogenic Bacterium
Authors: Signoretto Caterina , Marchi Anna , Bertoncelli Anna , Burlacchini Gloria , Tessarolo Francesco , Caola Iole , Pezzati Elisabetta , Zaura Egija , Papetti Adele , Lingström Peter , Pratten Jonathan , Spratt David A. , Wilson Michael , Canepari Pietro
Published: September 2011

Contrary to the common assumption that food has a negative impact on oral health, research has shown that several foods contain a number of components with antibacterial and antiplaque activity. These natural compounds may be useful for improving daily oral hygiene. In this study we evaluate the mode of antimicrobial action of fractions of mushroom and red chicory extracts on Prevotella intermedia, a periodontopathogenic bacterium. The minimal inhibitory concentration corresponded to 0.5x compared to the natural food concentration for both extracts. This concentration resulted in a bacteriostatic effect in mushroom extract and in a slightly bactericidal effect in chicory extract. Cell mass continued to increase even after division stopped. As regards macromolecular synthesis, DNA was almost totally inhibited upon addition of either mushroom or chicory extract, and RNA to a lesser extent, while protein synthesis continued. Cell elongation occurred after septum inhibition as documented by scanning electron microscopy and cell measurement. The morphogenetic effects are reminiscent of the mode of action of antibiotics such as quinolones or β‐lactams. The discovery of an antibiotic‐like mode of action suggests that these extracts can be advantageously employed for daily oral hygiene in formulations of cosmetic products such as mouthwashes and toothpastes.
Performance Analysis of Multilayered Multipriority Asymmetric-Sized Delta Networks
Authors: Vasiliadis D. C. , Rizos G. E. , Vassilakis C.
Published: September 2011

The performance of multilayered asymmetric-sized finite-buffered delta networks supporting multiclass routing traffic is presented and analyzed in the uniform traffic conditions under various loads using simulations. The rationale behind introducing asymmetric-sized buffered systems is to have a better exploitation of available buffer spaces, while the implementation of multilayered architecture is applied in order to further improve the overall performance of network. The findings of this performance evaluation can be used by network designers for drawing optimal configurations while setting up the network, so as to best meet the performance and cost requirements under the anticipated traffic load and quality of service specifications.
Large Deviations in Testing Squared Radial Ornstein‐Uhleneck Model
Authors: Zhao Shoujiang , Liu Qiaojing
Published: September 2011

We study the large deviations and moderate deviations of hypothesis testing for squared radial Ornstein‐Uhleneck model. Large deviation principles for the log‐likelihood ratio are obtained, by which we give negative regions in testing squared radial Ornstein‐Uhleneck model and get the decay rates of the error probabilities.
The Sulfate-Rich and Extreme Saline Sediment of the Ephemeral Tirez Lagoon: A Biotope for Acetoclastic Sulfate-Reducing Bacteria and Hydrogenotrophic Methanogenic Archaea
Authors: Montoya Lilia , Lozada-Chávez Irma , Amils Ricardo , Rodriguez Nuria , Marín Irma
Published: September 2011

Our goal was to examine the composition of methanogenic archaea (MA) and sulfate-reducing (SRP) and sulfur-oxidizing (SOP) prokaryotes in the extreme athalassohaline and particularly sulfate-rich sediment of Tirez Lagoon (Spain). Thus, adenosine-5′-phosphosulfate (APS) reductase α (aprA) and methyl coenzyme M reductase α (mcrA) gene markers were amplified given that both enzymes are specific for SRP, SOP, and MA, respectively. Anaerobic populations sampled at different depths in flooded and dry seasons from the anoxic sediment were compared qualitatively via denaturing gradient gel electrophoresis (DGGE) fingerprint analysis. Phylogenetic analyses allowed the detection of SRP belonging to Desulfobacteraceae, Desulfohalobiaceae, and Peptococcaceae in ∂-proteobacteria and Firmicutes and SOP belonging to Chromatiales/Thiotrichales clade and Ectothiorhodospiraceae in γ-proteobacteria as well as MA belonging to methylotrophic species in Methanosarcinaceae and one hydrogenotrophic species in Methanomicrobiaceae. We also estimated amino acid composition, GC content, and preferential codon usage for the AprA and McrA sequences from halophiles, nonhalophiles, and Tirez phylotypes. Even though our results cannot be currently conclusive regarding the halotolerant strategies carried out by Tirez phylotypes, we discuss the possibility of a plausible “salt-in” signal in SRP and SOP as well as of a speculative complementary haloadaptation between salt-in and salt-out strategies in MA.