bluuebunny/crossref_metadata_2025 huggingface dataset:
BEHAVIOUR OF SOCIALLY LIVING RHESUS MONKEYS IN THEIR FIRST SIX MONTHS
Authors: HINDE R. A. , BOWELL T. E. , SPENCER‐BOOTH Y.
Published: August 2010

A and B. The behaviour of eight rhesus monkeys during the first six months of life was studied. The animals were brought up by their natural mothers living in captivity in small social groups containing one adult male and three or four adult females.

C (i). Three births were witnessed. The placenta was not eaten in some cases.

C (ii). Many of the mothers held their babies in abnormal positions immediately after birth. They were often held so tightly that they could not turn their heads to gain the nipple.

D (i)The normal ventro‐ventral nursing position is described.

D (ii)The methods by which the infant finds the nipple are described. The time spent by the infant on the nipple with its eyes open rose to a peak of 35 per cent in the third week, and then declined (Fig. 1). Only a small proportion of the time spent on the nipple is occupied by sucking.

D (iii). A nipple preference is established during the first few weeks. This may not be a sucking preference.

D (iv). The proportion of time in which the infant's eyes were closed fell from 70 per cent in week 1 to about 25 per cent after five weeks, and then more slowly (Fig. 2). The proportion of time on the mother with the eyes open but not attached to the nipple rose to a peak of 22 per cent in weeks 7/8 (Fig. 3).

D (v). The way in which the mother carried the baby during locomotion is described. Riding on the mother's back was not common in our colony.

D (vi). Some observations on the development of eye‐hand‐mouth coordination are described. The ages at which certain criteria of achievement were reached are given in Table 3.

D (vii). The initiative for the first separation between mother and infant comes sometimes from the mother, sometimes from the infant.

D (viii). The proportion of time spent off the mother rose t o about 60 per cent after 16 weeks (Fig. 4).

D (ix). The ages at which certain criteria of achievement were attained are given in Table 4.

D (x). The manner in which the infant follows its mother is described.

D (xi). As the infants get older, the length of the periods which they spend off their mother increases (Fig. 5). After the sixth week the infant spends a considerable proportion of its time more than two feet from its mother (Figs. 6, 7 & 8).

D (xii). The relative roles of infant and mother in increasing and decreasing the distance between them are shown in Figs. 9 and 10.

D (xiii).The manner in which the mother protects and grooms the infant is described

D (xiv). The development of independent feeding is described. (Fig. 11). She also shows various types of “affectionate” behaviour without obvious function.

D (xv). As the infant gets older, there are a number of contexts in which its behaviour is not reciprocal to that of the mother. Mother‐infant incompatibility arises in the The development of independent feeding is described contexts of sucking, carrying, feeding, exploration and play.
TWO NEW SPECIES OF PABABATHYNELLA (CRUSTACEA: SYNCARIDA) FROM LAKE ALBERT, UGANDA
Authors: GREEN J.
Published: August 2010

Parabathynetla bakeri sp. n. and P. ninianae sp. n. are described and figured. These species were found in the interstitial water of a sand spit on the shore of Lake Albert, and are the second and third species of Parabathynella recorded from Africa. A synoptic table of the genus is given, and the genera Braailibathynella and Thermobathynella are discussed.
Bex1 is involved in the regeneration of axons after injury
Authors: Khazaei Mohammad R. , Halfter Hartmut , Karimzadeh Fereshteh , Koo Jae Hyung , Margolis Frank L. , Young Peter
Published: August 2010

J. Neurochem.(2010)115, 910–920.

Successful axonal regeneration is a complex process determined by both axonal environment and endogenous neural capability of the regenerating axons in the central and the peripheral nervous systems. Numerous external inhibitory factors inhibit axonal regeneration after injury. In response, neurons express various regeneration‐associated genes to overcome this inhibition and increase the intrinsic growth capacity. In the present study, we show that the brain‐expressed X‐linked (Bex1) protein was over‐expressed as a result of peripheral axonal damage. Bex1 antagonized the axon outgrowth inhibitory effect of myelin‐associated glycoprotein. The involvement of Bex1 in axon regeneration was further confirmedin vivo. We have demonstrated that Bex1 knock‐out mice showed lower capability for regeneration after peripheral nerve injury than wild‐type animals. Wild‐type mice could recover from sciatic nerve injury much faster than Bex1 knock‐out mice. Our findings suggest that Bex1 could be considered as regeneration‐associated gene.
GFR α‐1 receptor expression in the aging nigrostriatal and mesoaccumbens pathways
Authors: Pruett Brandon S. , Salvatore Michael F.
Published: August 2010

J. Neurochem.(2010)115, 707–715.

We recently reported that age‐related bradykinesia was associated with reduced dopamine (DA) tissue content, ser31 tyrosine hydroxylase (TH) phosphorylation, and total TH levels in substantia nigra (SN) only. In this study, we propose that these decreases result from reduced glial cell line‐derived neurotrophic factor family receptor α‐1 (GFR α‐1) levels in the aged (30‐month‐old) cohort of rats. Analysis of GFR α‐1 receptor protein in SN, striatum, ventral tegmental area, and nucleus accumbens from 12‐ and 30‐month‐old Brown‐Norway/Fischer 344 F1hybrid rats revealed immunoreactivity at ∼48 and 52 kDa, bands previously characterized to correspond to soluble and glycosyl‐phosphatidylinositol‐linked forms of GFR α‐1, respectively. The nigrostriatal pathway had significantly greater levels of the soluble GFR α‐1 than the mesoaccumbens pathway. Aging significantly reduced soluble and total GFR α‐1 in the SN. The levels of GFR α‐1 significantly correlated with TH protein in SN, striatum, and nucleus accumbens, but only in the SN did GFR α‐1 significantly correlate with DA levels. Based on these observations and findings from the literature, we speculate that (i) GFR α‐1 receptor expression may regulate nigral DA bioavailabilityin vivo, (ii) age‐related decreases in soluble GFR α‐1 in SN may contribute to bradykinesia in aging, and (iii) differences in expression of the GFR α‐1 forms between the nigrostriatal and mesoaccumbens pathways and allied tissue may indicate that glial cell line‐derived neurotrophic factor‐signaling differs between these DA pathways.
Follow‐up of adolescents born extremely preterm: self‐perceived mental health, social and relational outcomes
Authors: Hallin Anne‐Li , Stjernqvist Karin
Published: August 2010

Aim:  The aim of this study was to investigate whether adolescents born extremely preterm differ from full‐term born regarding mental health, social support and attachment style.

Methods:  Fifty‐one young adults born before the 29th gestational week and 54 born at term were investigated by self‐reports. Psychological health was measured by the Beck Youth Inventories of Emotional and Social Impairment, social support with the Interview Schedule of Social Interaction and attachment style with the Relationship Questionnaire.

Results:  No difference was noted regarding mental health. The preterm group described themselves as having less social interaction (p ≤ 0.001), but no difference was obtained regarding satisfaction with this circumstance. The prematurely born judged a preoccupied attachment style, concordant with a model of a negative self and positive other, to be applicable more often than the controls (p = 0.02).

Conclusion:  Extremely preterm born adolescents did not experience more problems regarding mental health compared to controls. Nevertheless, they reported less social interaction and, to a greater extent, a negative model of self.
Effects of Drug Hydrophobicity on Liposomal Stability
Authors: Khan David R. , Rezler Evonne M. , Lauer‐Fields Janelle , Fields Gregg B.
Published: August 2010

A major obstacle in drug delivery is the inability to effectively deliver drugs to their intended biological target without deleterious side‐effects. Delivery vehicles such as liposomes can minimize toxic side‐effects by shielding the drug from reaction with unintended targets while in systemic circulation. Liposomes have the ability to accommodate both hydrophilic and hydrophobic drugs, either in the internal aqueous core or the lipid bilayer, respectively. In the present study, fluorescein and rhodamine have been used to model hydrophilic and hydrophobic drugs, respectively. We have compared the stabilities of liposomes encapsulating these fluorophores as a function of lipid content, time, and temperature. At 25 and 37 °C, liposomes containing distearoyl phosphatidylcholine as the major phospholipid component were found to be more stable over time than those containing dipalmitoyl phosphatidylcholine, regardless of the fluorophore encapsulated. Liposomes loaded with fluorescein were found to be more stable than those with rhodamine. Dipalmitoyl phosphatidylcholine liposomes that encapsulated rhodamine were the least stable. The results indicate that the physical properties of the drug cargo play a role in the stability, and hence drug delivery kinetics, of liposomal delivery systems, and desired drug release times can be achieved by adjusting/fine‐tuning the lipid compositions.
Delay Dependent Robust Stabilization for Systems With Uncertain Time Varying Delays
Authors: Tissir El Houssaine
Published: August 2010

Sufficient and improved stability robustness conditions that depend both on the size and time derivative of time varying delays are presented. The approach is applied to investigate the problem of finding memoryless state feedback control that simultaneously stabilizes the uncertain system and guarantees an upper bound for some performance index. The perturbations are unknown but norm bounded. The results are derived via Lyapunov– Krasovskii functional and are expressed in terms of linear matrix inequalities. Numerical computations are performed to illustrate the feasibility and the improvements of the results with respect to previous works.
Magnetically Suspended VSCMGs for Simultaneous Attitude Control and Power Transfer IPAC Service
Authors: Park Junyoung , Palazzolo Alan
Published: August 2010

This paper presents the theory and numerical results of utilizing four gimbaled, magnetically suspended, variable speed flywheels for simultaneous satellite attitude control and power transfer (charge, storage, and delivery). Previous variable speed control moment gyro models and control algorithms assumed that the flywheel bearings were rigid. However, high speed flywheels on spacecraft will be supported by active magnetic bearings, which have flexibility and in general frequency dependent characteristics. The present work provides the theory for modeling the satellite and flywheel systems including controllers for stable magnetic bearing suspension for power transfer to and from the flywheels and for attitude control of the satellite. A major reason for utilizing flexible bearings is to isolate the imbalance disturbance forces from the flywheel to the satellite. This g-jitter vibration could interfere with the operation of sensitive onboard instrumentation. A special control approach is employed for the magnetic bearings to reject the imbalance disturbances. The stability, robustness, tracking, and disturbance rejection performances of the feedback control laws are demonstrated with a satellite simulation that includes initial attitude error, system modeling error, and flywheel imbalance disturbance.
PCCI Control Authority of a Modern Diesel Engine Outfitted With Flexible Intake Valve Actuation
Authors: Kulkarni Anup M. , Stricker Karla C. , Blum Angeline , Shaver Gregory M.
Published: August 2010

Premixed charge compression ignition (PCCI), an advanced mode combustion strategy, promises to simultaneously deliver the fuel efficiency of diesel combustion and the ultralow NOx emissions that usually require advanced exhaust aftertreatment. A flexible, computationally efficient, and whole engine simulation model for a 2007 6.7 l diesel engine with exhaust gas recirculation (EGR), variable geometry turbocharging (VGT), and common rail fuel injection was validated after extensive experimentation. This model was used to develop strategies for highly fuel-efficient and ultralow NOx emission PCCI. The primary aim of this modeling investigation is to determine the PCCI control authority present on a modern diesel engine outfitted with both conventional actuators (multipulse fuel injectors, EGR valve, and VGT) and flexible intake valve closure modulation, which dictates the effective compression ratio. The results indicate that early fuel injection coupled with ECR reduction and modest amounts of EGR yield a well-timed PCCI exhibiting 70%+ reductions in NOx with no fuel consumption penalty over a significant portion of the engine operating range.
Line Up for Movement
Authors: Hurtley Stella M.
Published: August 2010

An actin-dependent mechanism is involved in moving nuclei so that they are properly positioned for cell migration.
Antimicrobial Resistance Testing of Verocytotoxin-Producing
Escherichia coli
and First Description of TEM-52 Extended-Spectrum β-Lactamase in Serogroup O26
Authors: Buvens Glenn , Bogaerts Pierre , Glupczynski Youri , Lauwers Sabine , Piérard Denis
Published: August 2010

We have investigated the antimicrobial resistance of verocytotoxin-producing
Escherichia coli
(VTEC) strains isolated from humans, animals, food, and the environment in Belgium. Resistance was more frequent in non-O157 strains from humans than in O157 strains from humans or other sources, and among non-O157 VTEC strains, intimin-positive strains were more resistant than intimin-negative strains. We also report the first VTEC strain producing an IncI1 extended-spectrum β-lactamase encoded by plasmid-borne
bla
TEM-52
; this β-lactamase was previously associated with
Salmonella enterica
and
E. coli
isolates from different origins.
Impact of
cyp51A
Mutations on the Pharmacokinetic and Pharmacodynamic Properties of Voriconazole in a Murine Model of Disseminated Aspergillosis
Authors: Mavridou Eleftheria , Bruggemann Roger J. M. , Melchers Willem J. G. , Verweij Paul E. , Mouton Johan W.
Published: August 2010

The
in vivo
efficacy of voriconazole against 4 clinical
Aspergillus fumigatus
isolates with MICs ranging from 0.125 to 2 mg/liter (CLSI document M38A) was assessed in a nonneutropenic murine model of disseminated aspergillosis. The study involved TR/L98H, M220I, and G54W mutants and a wild-type control isolate. Oral voriconazole therapy was started 24 h after intravenous infection of mice and was given once daily for 14 consecutive days, with doses ranging from 10 to 80 mg/kg of body weight, using survival as the endpoint. Survival for all isolates was dependent on the voriconazole dose level (
R
2
value of 0.5 to 0.6), but a better relationship existed for the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC/MIC ratio) or the AUC for the free, unbound fraction of the drug divided by the MIC (
f
AUC/MIC ratio) (
R
2
value of 0.95 to 0.98). The 24-h
f
AUC/MIC ratio showed a clear relationship to effect, with an exposure index for amount of free drug required for 50% of maximum effectiveness (
f
EI
50
) of 11.17 at day 7. Maximum effect was reached at values of around 80 to 100, comparable to that observed for posaconazole and
A. fumigatus
. Mice infected with an isolate having a MIC of 2 mg/liter required an exposure that was inversely correlated with the increase in MIC compared to that of the wild-type control, but due to nonlinear pharmacokinetics, this required only doubling of the voriconazole dose. The efficacy of voriconazole for isolates with high MICs for other triazoles but voriconazole MICs within the wild-type population range was comparable to that for the wild-type control. Finally, we used a grapefruit juice-free murine model of aspergillosis and concluded that this model is appropriate to study pharmacokinetic/pharmacodynamic relationships of voriconazole.
Systematic Review and Meta-Analysis of the Efficacy of Appropriate Empiric Antibiotic Therapy for Sepsis
Authors: Paul Mical , Shani Vered , Muchtar Eli , Kariv Galia , Robenshtok Eyal , Leibovici Leonard
Published: August 2010

Quantifying the benefit of early antibiotic treatment is crucial for decision making and can be assessed only in observational studies. We performed a systematic review of prospective studies reporting the effect of appropriate empirical antibiotic treatment on all-cause mortality among adult inpatients with sepsis. Two reviewers independently extracted data. Risk of bias was assessed using the Newcastle-Ottawa score. We calculated unadjusted odds ratios (ORs) with 95% confidence intervals for each study and extracted adjusted ORs, with variance, methods, and covariates being used for adjustment. ORs were pooled using random-effects meta-analysis. We examined the effects of methodological and clinical confounders on results through subgroup analysis or mixed-effect meta-regression. Seventy studies were included, of which 48 provided an adjusted OR for inappropriate empirical antibiotic treatment. Inappropriate empirical antibiotic treatment was associated with significantly higher mortality in the unadjusted and adjusted comparisons, with considerable heterogeneity occurring in both analyses (
I
2
> 70%). Study design, time of mortality assessment, the reporting methods of the multivariable models, and the covariates used for adjustment were significantly associated with effect size. Septic shock was the only clinical variable significantly affecting results (it was associated with higher ORs). Studies adjusting for background conditions and sepsis severity reported a pooled adjusted OR of 1.60 (95% confidence interval = 1.37 to 1.86; 26 studies; number needed to treat to prevent one fatal outcome, 10 patients [95% confidence interval = 8 to 15];
I
2
= 46.3%) given 34% mortality with inappropriate empirical treatment. Appropriate empirical antibiotic treatment is associated with a significant reduction in all-cause mortality. However, the methods used in the observational studies significantly affect the effect size reported. Methods of observational studies assessing the effects of antibiotic treatment should be improved and standardized.
vanM
, a New Glycopeptide Resistance Gene Cluster Found in
Enterococcus faecium
Authors: Xu Xiaogang , Lin Dongfang , Yan Guoquan , Ye Xinyu , Wu Shi , Guo Yan , Zhu Demei , Hu Fupin , Zhang Yingyuan , Wang Fu , Jacoby George A. , Wang Minggui
Published: August 2010

Since glycopeptide-resistant enterococci (GRE) were reported in 1988, they have appeared in hospitals worldwide. Seven
van
gene cluster types (
vanA
,
vanB
,
vanC
,
vanD
,
vanE
,
vanG
, and
vanL
) are currently known. We investigated a clinical strain of
Enterococcus
faecium
Efm-HS0661 that was isolated in 2006 from an inpatient with intra-abdominal infection in Shanghai. It was resistant to most antimicrobials, including vancomycin (MIC, >256 μg/ml) and teicoplanin (MIC, 96 μg/ml). Glycopeptide resistance could be transferred to
E
.
faecium
BM4105RF by conjugation. The donor and its transconjugant were negative by PCR for the known
van
genes. By cloning and primer walk sequencing, we discovered a novel
van
gene cluster, designated
vanM
. The
vanM
ligase gene was 1,032-bp in length and encoded a 343-amino-acid protein that shared 79.9, 70.8, 66.3, and 78.8% amino acid identity with VanA, VanB, VanD, and VanF, respectively. Although the
vanM
DNA sequence was closest to
vanA
, the organization of the
vanM
gene cluster was most similar to that of
vanD
. Upstream from the
vanM
cluster was an IS
1216-
like element, which may play a role in the dissemination of this resistance determinant. Liquid chromatography-mass spectrometry analysis of peptidoglycan precursors extracted from the VanM-type strain Efm-HS0661 treated with vancomycin or teicoplanin revealed a modified precursor (UDP-
N
-acetylmuramic acid [MurNAc]-tetrapeptide-
d
-Lac), indicating that VanM, like VanA, confers glycopeptide resistance by the inducible synthesis of precursor ending in
d
-Ala-
d
-Lac.
Phenotypic and Biochemical Comparison of the Carbapenem-Hydrolyzing Activities of Five Plasmid-Borne AmpC β-Lactamases
Authors: Mammeri Hedi , Guillon Hélène , Eb François , Nordmann Patrice
Published: August 2010

The CMY-2, ACT-1, DHA-1, ACC-1, and FOX-1 enzymes are representative of five plasmid-mediated AmpC (pAmpC) β-lactamase clusters. Resistance to imipenem has been reported in
Enterobacteriaceae
as a result of pAmpC expression combined with decreased outer membrane permeability. The aim of this study was to determine the role of different pAmpCs in carbapenem resistance and to define the structure/activity relationship supporting carbapenemase activity. The
ampC
genes encoding the five pAmpCs and the chromosomal AmpC of
Escherichia coli
EC6, which was used as a reference cephalosporinase, were cloned and introduced into wild-type
E. coli
TOP10 and OmpC/OmpF porin-deficient
E. coli
HB4 strains. The MICs of β-lactams for the recombinant strains revealed that CMY-2, ACT-1, and DHA-1 β-lactamases conferred a high level of resistance to ceftazidime and cefotaxime once expressed in
E. coli
TOP10 and reduced significantly the susceptibility to imipenem once expressed in
E. coli
HB4. In contrast, FOX-1 and ACC-1 enzymes did not confer resistance to imipenem. Biochemical analysis showed that CMY-2 β-lactamase and, to a lesser extent, ACT-1 exhibited the highest catalytic efficiency toward imipenem and showed low

K
m

values. A modeling study revealed that the large R2 binding site of these two enzymes may support the carbapenemase activity. Therefore, CMY-2-type, ACT-1-type, and DHA-1-type β-lactamases may promote the emergence of carbapenem resistance in porin-deficient clinical isolates.
Specific Resistance to
Pseudomonas aeruginosa
Infection in Zebrafish Is Mediated by the Cystic Fibrosis Transmembrane Conductance Regulator
Authors: Phennicie Ryan T. , Sullivan Matthew J. , Singer John T. , Yoder Jeffrey A. , Kim Carol H.
Published: August 2010

Cystic fibrosis (CF) is a genetic disease caused by recessive mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and is associated with prevalent and chronic
Pseudomonas aeruginosa
lung infections. Despite numerous studies that have sought to elucidate the role of CFTR in the innate immune response, the links between CFTR, innate immunity, and
P. aeruginosa
infection remain unclear. The present work highlights the zebrafish as a powerful model organism for human infectious disease, particularly infection by
P. aeruginosa
. Zebrafish embryos with reduced expression of the
cftr
gene (Cftr morphants) exhibited reduced respiratory burst response and directed neutrophil migration, supporting a connection between
cftr
and the innate immune response. Cftr morphants were infected with
P. aeruginosa
or other bacterial species that are commonly associated with infections in CF patients, including
Burkholderia cenocepacia
,
Haemophilus influenzae
, and
Staphylococcus aureus
. Intriguingly, the bacterial burden of
P. aeruginosa
was found to be significantly higher in zebrafish Cftr morphants than in controls, but this phenomenon was not observed with the other bacterial species. Bacterial burden in Cftr morphants infected with a
P. aeruginosa
ΔLasR mutant, a quorum sensing-deficient strain, was comparable to that in control fish, indicating that the regulation of virulence factors through LasR is required for enhancement of infection in the absence of Cftr. The zebrafish system provides a multitude of advantages for studying the pathogenesis of
P. aeruginosa
and for understanding the role that innate immune cells, such as neutrophils, play in the host response to acute bacterial infections commonly associated with cystic fibrosis.
Human Intestinal Tissue and Cultured Colonic Cells Contain Globotriaosylceramide Synthase mRNA and the Alternate Shiga Toxin Receptor Globotetraosylceramide
Authors: Zumbrun Steven D. , Hanson Leanne , Sinclair James F. , Freedy James , Melton-Celsa Angela R. , Rodriguez-Canales Jaime , Hanson Jeffrey C. , O'Brien Alison D.
Published: August 2010

Escherichia coli
O157:H7 and other Shiga toxin (Stx)-producing
E. coli
(STEC) bacteria are not enteroinvasive but can cause hemorrhagic colitis. In some STEC-infected individuals, a life-threatening sequela of infection called the hemolytic uremic syndrome may develop that can lead to kidney failure. This syndrome is linked to the production of Stx by the infecting organism. For Stx to reach the kidney, the toxin must first penetrate the colonic epithelial barrier. However, the Stx receptor, globotriaosylceramide (Gb3), has been thought to be absent from human intestinal epithelial cells. Thus, the mechanisms by which the toxin associates with and traverses through the intestine en route to the kidneys have been puzzling aspects of STEC pathogenesis. In this study, we initially determined that both types of Stx made by STEC, Stx1 and Stx2, do in fact bind to colonic epithelia in fresh tissue sections and to a colonic epithelial cell line (HCT-8). We also discovered that globotetraosylceramide (Gb4), a lower-affinity toxin receptor derived from Gb3, is readily detectable on the surfaces of human colonic tissue sections and HCT-8 cells. Furthermore, we found that Gb3 is present on a fraction of HCT-8 cells, where it presumably functions to bind and internalize Stx1 and Stx2. In addition, we established by quantitative real-time PCR (qRT-PCR) that both fresh colonic epithelial sections and HCT-8 cells express Gb3 synthase mRNA. Taken together, our data suggest that Gb3 may be present in small quantities in human colonic epithelia, where it may compete for Stx binding with the more abundantly expressed glycosphingolipid Gb4.
Proximal migration and compaction of an Enterprise stent into a coiled basilar apex aneurysm: a posterior circulation phenomenon?
Authors: Dashti Shervin R , Fiorella David , Toledo Maria M , Hu Yin , McDougall Cameron G , Albuquerque Felipe C
Published: August 2010

A patient with a giant partially thrombosed basilar apex aneurysm was treated with balloon-assisted coil embolization. At the conclusion of the embolization, an Enterprise stent was placed from the upper basilar artery to the left P1 segment. Follow-up angiography 4 months later showed that the distal stent had pulled out of the posterior cerebral artery and was in the coil mass within the aneurysm. Angiography clearly showed that the stent had migrated down the basilar artery and that the artery was now kinked proximal to the stent. Nonetheless, the left posterior cerebral artery and the basilar artery were still widely patent. This is the first documented case in which a stent ‘compacted’ into a completed coiled aneurysm in a delayed fashion.
EXPLAINING THE PRICE OF VOLUNTARY CARBON OFFSETS
Authors: CONTE MARC N. , KOTCHEN MATTHEW J.
Published: August 2010

This paper identifies factors that explain the large variability in the price of voluntary carbon offsets. We estimate hedonic price functions using a variety of provider- and project-level characteristics as explanatory variables. We find that providers located in Europe sell offsets at prices that are approximately 30% higher than providers located in either North America or Australasia. Contrary to what one might expect, offset prices are generally higher, by roughly 20%, when projects are located in developing or least-developed nations. But this result does not hold for forestry-based projects. We find evidence that forestry-based offsets sell at lower prices, and the result is particularly strong when projects are located in developing or least-developed nations. Offsets that are certified under the Clean Development Mechanism or the Gold Standard, and therefore qualify for emission reductions under the Kyoto Protocol, sell at a premium of more than 30%; however, third-party certification from the Voluntary Carbon Standard, one of the popular certifiers, is associated with a price discount. Variables that have no effect on offset prices are the number of projects that a provider manages and a provider's status as for-profit or not-for-profit.
AjaxScope
Authors: Kiciman Emre , Livshits Benjamin
Published: August 2010

The rise of the software-as-a-service paradigm has led to the development of a new breed of sophisticated, interactive applications often called Web 2.0. While web applications have become larger and more complex, web application developers today have little visibility into the end-to-end behavior of their systems. This paper presents AjaxScope, a dynamic instrumentation platform that enables cross-user monitoring and just-in-time control of web application behavior on end-user desktops. AjaxScope is a proxy that performs on-the-fly parsing and instrumentation of JavaScript code as it is sent to users' browsers. AjaxScope provides facilities for distributed and adaptive instrumentation in order to reduce the client-side overhead, while giving fine-grained visibility into the code-level behavior of web applications. We present a variety of policies demonstrating the power of AjaxScope, ranging from simple error reporting and performance profiling to more complex memory leak detection and optimization analyses. We also apply our prototype to analyze the behavior of over 90 Web 2.0 applications and sites that use large amounts of JavaScript.
Secure web applications via automatic partitioning
Authors: Chong Stephen , Liu Jed , Myers Andrew C. , Qi Xin , Vikram K. , Zheng Lantian , Zheng Xin
Published: August 2010

Swift is a new, principled approach to building web applications that are
secure by construction
. In modern web applications, some application functionality is usually implemented as client-side code written in JavaScript. Moving code and data to the client can create security vulnerabilities, but currently there are no good methods for deciding when it is secure to do so. Swift automatically partitions application code while providing assurance that the resulting placement is secure and efficient. Application code is written as Java-like code annotated with information flow policies that specify the confidentiality and integrity of web application information. The compiler uses these policies to automatically partition the program into JavaScript code running in the browser, and Java code running on the server. To improve interactive performance, code and data are placed on the client side. However, security-critical code and data are always placed on the server. Code and data can also be replicated across the client and server, to obtain both security and performance. A max-flow algorithm is used to place code and data in a way that minimizes client-server communication.
Tolerating byzantine faults in transaction processing systems using commit barrier scheduling
Authors: Vandiver Ben , Balakrishnan Hari , Liskov Barbara , Madden Sam
Published: August 2010

This paper describes the design, implementation, and evaluation of areplication scheme to handle Byzantine faults in transaction processing database systems. The scheme compares answers from queries and updates on multiple replicas which are unmodified, off-the-shelf systems, to provide a single database that is Byzantine fault tolerant. The scheme works when the replicas are homogeneous, but it also allows heterogeneous replication in which replicas come from different vendors. Heterogeneous replicas reduce the impact of bugs and security compromises because they are implemented independently and are thus less likely to suffer correlated failures.

The main challenge in designing a replication scheme for transactionprocessing systems is ensuring that the different replicas execute transactions in equivalent serial orders while allowing a high degreeof concurrency. Our scheme meets this goal using a novel concurrency control protocol, commit barrier scheduling (CBS). We have implemented CBS in the context of a replicated SQL database, HRDB(Heterogeneous Replicated DB), which has been tested with unmodified production versions of several commercial and open source databases as replicas. Our experiments show an HRDB configuration that can tolerate one faulty replica has only a modest performance overhead(about 17% for the TPC-C benchmark). HRDB successfully masks several Byzantine faults observed in practice and we have used it to find a new bug in MySQL.
/*icomment
Authors: Tan Lin , Yuan Ding , Krishna Gopal , Zhou Yuanyuan
Published: August 2010

Commenting source code has long been a common practice in software development. Compared to source code, comments are more
direct
,
descriptive
and
easy-to-understand
. Comments and sourcecode provide relatively redundant and independent information regarding a program's semantic behavior. As software evolves, they can easily grow out-of-sync, indicating two problems: (1) bugs -the source code does not follow the assumptions and requirements specified by correct program comments; (2) bad comments - comments that are inconsistent with correct code, which can confuse and mislead programmers to introduce bugs in subsequent versions. Unfortunately, as most comments are written in natural language, no solution has been proposed to automatically analyze commentsand detect inconsistencies between comments and source code. This paper takes the first step in automatically analyzing commentswritten in natural language to extract implicit program rulesand use these rules to automatically detect inconsistencies between comments and source code, indicating either bugs or bad comments. Our solution, iComment, combines Natural Language Processing(NLP), Machine Learning, Statistics and Program Analysis techniques to achieve these goals. We evaluate iComment on four large code bases: Linux, Mozilla, Wine and Apache. Our experimental results show that iComment automatically extracts 1832 rules from comments with 90.8-100% accuracy and detects 60 comment-code inconsistencies, 33 newbugs and 27 bad comments, in the latest versions of the four programs. Nineteen of them (12 bugs and 7 bad comments) have already been confirmed by the corresponding developers while the others are currently being analyzed by the developers.
Sinfonia
Authors: Aguilera Marcos K. , Merchant Arif , Shah Mehul , Veitch Alistair , Karamanolis Christos
Published: August 2010

We propose a new paradigm for building scalable distributed systems. Our approach does not require dealing with message-passing protocols -- a major complication in existing distributed systems. Instead, developers just design and manipulate data structures within our service called Sinfonia. Sinfonia keeps data for applications on a set of memory nodes, each exporting a linear address space. At the core of Sinfonia is a novel minitransaction primitive that enables efficient and consistent access to data, while hiding the complexities that arise from concurrency and failures. Using Sinfonia, we implemented two very different and complex applications in a few months: a cluster file system and a group communication service. Our implementations perform well and scale to hundreds of machines.
VirtualPower
Authors: Nathuji Ripal , Schwan Karsten
Published: August 2010

Power management has become increasingly necessary in large-scale datacenters to address costs and limitations in cooling or power delivery. This paper explores how to integrate power management mechanisms and policies with the virtualization technologies being actively deployed in these environments. The goals of the proposed
VirtualPower
approach to online power management are (i) to support the isolated and independent operation assumed by guest virtual machines (VMs) running on virtualized platforms and (ii) to make it possible to control and globally coordinate the effects of the diverse power management policies applied by these VMs to virtualized resources. To attain these goals, VirtualPower extends to guest VMs `soft' versions of the hardware power states for which their policies are designed. The resulting technical challenge is to appropriately map VM-level updates made to soft power states to actual changes in the states or in the allocation of underlying virtualized hardware. An implementation of VirtualPower Management (VPM) for the Xen hypervisor addresses this challenge by provision of multiple system-level abstractions including VPM states, channels, mechanisms, and rules. Experimental evaluations on modern multicore platforms highlight resulting improvements in online power management capabilities, including minimization of power consumption with little or no performance penalties and the ability to throttle power consumption while still meeting application requirements. Finally, coordination of online methods for server consolidation with VPM management techniques in heterogeneous server systems is shown to provide up to 34% improvements in power consumption.
SecVisor
Authors: Seshadri Arvind , Luk Mark , Qu Ning , Perrig Adrian
Published: August 2010

We propose SecVisor, a tiny hypervisor that ensures code integrity for commodity OS kernels. In particular, SecVisor ensures that only user-approved code can execute in kernel mode over the entire system lifetime. This protects the kernel against code injection attacks, such as kernel rootkits. SecVisor can achieve this propertyeven against an attacker who controls everything but the CPU, the memory controller, and system memory chips. Further, SecVisor can even defend against attackers with knowledge of zero-day kernel exploits.

Our goal is to make SecVisor amenable to formal verificationand manual audit, thereby making it possible to rule out known classes of vulnerabilities. To this end, SecVisor offers small code size and small external interface. We rely on memory virtualization to build SecVisor and implement two versions, one using software memory virtualization and the other using CPU-supported memory virtualization. The code sizes of the runtime portions of these versions are 1739 and 1112 lines, respectively. The size of the external interface for both versions of SecVisor is 2 hypercalls. It is easy to port OS kernels to SecVisor. We port the Linux kernel version 2.6.20 by adding 12 lines and deleting 81 lines, out of a total of approximately 4.3 million lines of code in the kernel.
Secure virtual architecture
Authors: Criswell John , Lenharth Andrew , Dhurjati Dinakar , Adve Vikram
Published: August 2010

This paper describes an efficient and robust approach to provide a
safe execution environment
for an entire operating system, such as Linux, and all its applications. The approach, which we call
Secure Virtual Architecture
(SVA), defines a virtual, low-level, typed instruction set suitable for executing all code on a system, including kernel and application code. SVA code is translated for execution by a virtual machine transparently, offline or online. SVA aims to enforce
fine-grained (object level) memory safety, control-flow integrity, type safety for a subset of objects
, and
sound analysis
. A virtual machine implementing SVA achieves these goals by using a novel approach that exploits properties of existing memory pools in the kernel and by preserving the kernel's explicit control over memory, including custom allocators and explicit deallocation. Furthermore, the safety properties can be encoded compactly as extensions to the SVA type system, allowing the (complex) safety checking compiler to be outside the trusted computing base. SVA also defines a set of OS interface operations that abstract all privileged hardware instructions, allowing the virtual machine to monitor all privileged operations and control the physical resources on a given hardware platform. We have ported the Linux kernel to SVA, treating it as a new architecture, and made only minimal code changes (less than 300 lines of code) to the machine-independent parts of the kernel and device drivers. SVA is able to prevent 4 out of 5 memory safety exploits previously reported for the Linux 2.4.22 kernel for which exploit code is available, and would prevent the fifth one simply by compiling an additional kernel library.
Proving non-termination
Authors: Gupta Ashutosh , Henzinger Thomas A. , Majumdar Rupak , Rybalchenko Andrey , Xu Ru-Gang
Published: August 2010

The search for proof and the search for counterexamples (bugs) are complementary activities that need to be pursued concurrently in order to maximize the practical success rate of verification tools.While this is well-understood in safety verification, the current focus of liveness verification has been almost exclusively on the search for termination proofs. A counterexample to termination is an infinite programexecution. In this paper, we propose a method to search for such counterexamples. The search proceeds in two phases. We first dynamically enumerate lasso-shaped candidate paths for counterexamples, and then statically prove their feasibility. We illustrate the utility of our nontermination prover, called TNT, on several nontrivial examples, some of which require bit-level reasoning about integer representations.
Relational inductive shape analysis
Authors: Chang Bor-Yuh Evan , Rival Xavier
Published: August 2010

Shape analyses are concerned with precise abstractions of the heap to capture detailed structural properties. To do so, they need to build and decompose summaries of disjoint memory regions. Unfortunately, many data structure invariants require relations be tracked across disjoint regions, such as intricate numerical data invariants or structural invariants concerning back and cross pointers. In this paper, we identify issues inherent to analyzing relational structures and design an abstract domain that is parameterized both by an abstract domain for pure data properties and by user-supplied specifications of the data structure invariants to check. Particularly, it supports hybrid invariants about shape and data and features a generic mechanism for materializing summaries at the beginning, middle, or end of inductive structures. Around this domain, we build a shape analysis whose interesting components include a pre-analysis on the user-supplied specifications that guides the abstract interpretation and a widening operator over the combined shape and data domain. We then demonstrate our techniques on the proof of preservation of the red-black tree invariants during insertion.
Multiparty asynchronous session types
Authors: Honda Kohei , Yoshida Nobuko , Carbone Marco
Published: August 2010

Communication is becoming one of the central elements in software development. As a potential typed foundation for structured communication-centred programming, session types have been studied over the last decade for a wide range of process calculi and programming languages, focussing on binary (two-party) sessions. This work extends the foregoing theories of binary session types to multiparty, asynchronous sessions, which often arise in practical communication-centred applications. Presented as a typed calculus for mobile processes, the theory introduces a new notion of types in which interactions involving multiple peers are directly abstracted as a global scenario. Global types retain a friendly type syntax of binary session types while capturing complex causal chains of multiparty asynchronous interactions. A global type plays the role of a shared agreement among communication peers, and is used as a basis of efficient type checking through its projection onto individual peers. The fundamental properties of the session type discipline such as communication safety, progress and session fidelity are established for generaln-party asynchronous interactions.
Clowns to the left of me, jokers to the right (pearl)
Authors: McBride Conor
Published: August 2010

This paper introduces a small but useful generalisation to the 'derivative' operation on datatypes underlying Huet's notion of 'zipper', giving a concrete representation to one-hole contexts in data which is undergoing transformation. This operator, 'dissection', turns a container-like functor into a bifunctor representing a one-hole context in which elements to the left of the hole are distinguished in type from elements to its right.

I present dissection here as a generic program, albeit for polynomial functors only. The notion is certainly applicable more widely, but here I prefer to concentrate on its diverse applications. For a start, map-like operations over the functor and fold-like operations over the recursive data structure it induces can be expressed by tail recursion alone. Further, the derivative is readily recovered from the dissection. Indeed, it is the dissection structure which delivers Huet's operations for navigating zippers.

The original motivation for dissection was to define 'division', capturing the notion of leftmost hole, canonically distinguishing values with no elements from those with at least one. Division gives rise to an isomorphism corresponding to the remainder theorem in algebra. By way of a larger example, division and dissection are exploited to give a relatively efficient generic algorithm for abstracting all occurrences of one term from another in a first-order syntax. The source code for the paper is available online and compiles with recent extensions to the Glasgow Haskell Compiler.
Circuit optimization techniques to mitigate the effects of soft errors in combinational logic
Authors: Rao Rajeev R. , Joshi Vivek , Blaauw David , Sylvester Dennis
Published: August 2010

Soft errors in combinational logic circuits are emerging as a significant reliability problem for VLSI designs. Technology scaling trends indicate that the soft error rates (SER) of logic circuits will be dominant factor for future technology generations. SER mitigation in logic can be accomplished by optimizing either the gates inside a logic block or the flipflops present on the block boundaries. We present novel circuit optimization techniques that target these elements separately as well as in unison to reduce the SER of combinational logic circuits.

First, we describe the construction of a new class of flip-flop variants that leverage the effect of temporal masking by selectively increasing the length of the latching window thereby preventing faulty transients from being registered. In contrast to previous flip-flop designs that rely on logic duplication and complicated circuit design styles, the new variants are redesigned from the library flip-flop using efficient transistor sizing. We then propose a flip-flop selection method that uses slack information at each primary output node to determine the flip-flop configuration that produces maximum SER savings. Next, we propose a gate sizing algorithm that trades off SER reduction and area overhead. This approach first computes bounds on the maximum achievable SER reduction by resizing a gate. This bound is then used to prune the circuit graph, arriving at a smaller set of candidate gates on which we perform incremental sensitivity computations to determine the gates that are the largest contributors to circuit SER. Third, we propose a unified, co-optimization approach combining flip-flop selection with the gate sizing algorithm. The joint optimization algorithm produces larger SER reductions while incurring smaller circuit overhead than either technique taken in isolation. Experimental results on a variety of benchmarks show average SER reductions of 10.7X with gate sizing, 5.7X with flip-flop assignment, and 30.1X for the combined optimization approach, with no delay penalties and area overheads within 5-6%. The runtimes for the optimization algorithms are on the order of 1-3 minutes.