bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of an Hourglass-Shape Tapered Sleeve on the Performance of the Fluid Dynamic Bearings of a HDD Spindle Motor
Authors: Lee J. H. , Lee M. H. , Jang G. H.
Published: December 2013

Fluid dynamic bearings (FDBs) of a HDD spindle motor support the rotating disk-spindle system through the pressure generated in the fluid lubricant. The radial and axial clearances of a 2.5″ HDD spindle motor are approximately 2 and 30 micro-meters, respectively, and herringbone or spiral grooves are inscribed in the sleeve of journal or thrust bearings to provide pumping pressure. One of the difficult manufacturing processes is to inscribe uniform grooves, especially groove depth in the range of several micro meters. Grooves are inscribed on the surface of the stainless steel sleeve by the electro chemical machining (ECM) which generally generates rough surface of the sleeve in grooved bearing. Ball-sizing process is used to scrape down rough surface. When a ball passes through the sleeve of FDBs to make rough surface smooth, compressive pressure is generated between ball and sleeve inlet and between ball and sleeve outlet, respectively. It forms an hourglass-shape tapered sleeve as shown in Figure 1, and tapered sleeve generally decreases the static and dynamic performance of the FDBs and the HDD spindle system, consequently.
Statistical Energy Analysis on Vibrational Energy Transmission in Hard Disk Drive Components
Authors: Ajavakom Nopdanai , Tanthanasirikul Pinporn
Published: December 2013

One of the problems found in the 2.5-inch hard disk drives (HDD) in operation is its vibration. Aiming to find important information to help reduce the vibration transmitted to the outer shell of HDD, the parameters involving vibrational energy transmission among the main components of HDD are identified by the test-based Statistical Energy Analysis (SEA). First, the vibration tests of HDD in the idle mode are performed in order to identify the contribution of the main components; the platters and the top cover, to the overall vibration of HDD. Second, the SEA parameters including the dissipation loss factors of the components and coupling loss factors of the pairs of the components are then experimentally determined in order to calculate the vibration transmission power among the components.
Experimental and Theoretical Study of Replenishment Speed of Depleted Scar in Submonolayer Lubricant
Authors: Ono Kyosuke
Published: December 2013

The evaluation of submonolayer lubricant mobility is becoming increasingly important in hard disk drives, in which the thickness of the lubricant has been reduced to one monolayer and that of the mobile lubricant layer has been reduced to less than 0.3 nm. To decrease the head–disk spacing significantly, a design concept of surfing–recording is proposed, in which a protruding small head’s surface slides on the mobile lubricant layer without solid–solid contact [1]. However, its feasibility has not yet been confirmed because the durability of the mobile and bonded lubricants with respect to the head–disk sliding contact has not been elucidated well.
Dimension Effect of Embedded Contact Sensor on Disk Defect Detection
Authors: Furukawa Masaru , Xu Junguo , Li Jianhua
Published: December 2013

A thermal contact sensor embedded in a magnetic-head slider was developed. The sensor has been used for contact detection between a head slider and a disk in hard disk drives, and, our previous research has shown that the sensor could successfully detect disk defects including asperities and pits. In this work, the sensor dimension effect and characterization of defect size was studied in order to better understanding of defect size. The results showed that the defect size can be clarified by considering sensor size and scan pitch.
Investigation of Head Burnishing of Thermal Flying Height Control Sliders
Authors: Matthes Liane , Brunner Ralf , Knigge Bernhard , Talke Frank E.
Published: December 2013

The head-disk spacing in current hard disk drives is approximately 1–2 nm. This distance is on the same order as the peak to valley surface roughness of a typical thin film disk. If one attempts to reduce the head-disk spacing even more, intermittent contacts between the slider and the disk are more likely to occur. Intermittent contacts are undesirable since they can result in slider and disk wear, lubricant transfer or degradation of the read and write elements.
Calculation and Measurement of Magnetic and Transport Properties of Rectangle Anti-Dot Arrays
Authors: Matsuki Takanori , Warisawa Shinichi , Yamada Ichiro
Published: December 2013

The recent advances in nanofabrication techniques have made it possible to engineer the magnetic and transport properties of thin magnetic films. The ability to design magnetic behavior is useful for technologies such as development of high-density hard disk drive (HDD) or magnetic random access memory (MRAM). In order to achieve high density in HDD, it is necessary to overcome the limit of super-paramagnetic effect. One way to solve this problem is to increase the anisotropic effect that can resist the external field and provide a net magnetic moment in remanence[1].
Experimental Study of Suspension and Slider Vibrations Measured by Laser Doppler Vibrometer
Authors: Nishida Tatsuhiko , Hanya Masao
Published: December 2013

The magnetic spacing of Hard Disk Drives (HDD) needs to be reduced for high recording density. On the other hand, it is necessary to prevent contact between the slider and disk for reliability of HDDs. Various research was carried out for the flying stability of the slider [1–3]. Furthermore, the magnetic track width also needs to be narrowed for high recording density. The Dual Stage Actuator (DSA) servo system is used for high positioning accuracy [4]. The DSA servo system uses a piezoelectric actuator on a suspension in addition to Voice Coil Motor (VCM). In this study, we measured vibrations to the slider and suspension caused by the PZT and VCM actuations. Two Laser Doppler Vibrometers (LDV) were used for the measurement. Moreover, we performed a numerical analysis to estimate the roll moment of the Air Bearing Surface (ABS) of the slider caused by PZT actuation. As results, we confirmed that the ABS vibrated in vertical direction due to the suspension’s vibrations caused by PZT and VCM actuations.
The Effect of Velocity and Local Pressure Changes on Lubricant Transfer: A Molecular Dynamics Simulation
Authors: Pan Deng , Ovcharenko Andrey , Yang Min , Talke Frank E.
Published: December 2013

A model for lubricant transfer from a rotating magnetic recording disk to a magnetic recording slider is developed using molecular dynamics simulation. The effects of disk velocity and local pressure changes on lubricant transfer are investigated.
A Near Zero Skew Actuation Mechanism for Hard Disk Drives
Authors: He Zhimin , Mou Jianqiang , Chan Kheong Sann , Lam Suet Hoi , See Boon Long , Lin Wuzhong
Published: December 2013

One of the issues in VCM rotary actuation in hard disk drives (HDDs) is the excessive sensitivity of the system to the skew angle. The rotation of the VCM from the inner diameter (ID) to the outer diameter (OD) of the disk results in an angle of skew between the read/write head and the track. The difference in skew angle, between the ID to the OD can be as large as 25 to 30 degrees in conventional 3.5″ and 2.5″ HDDs. A large skew angle affects the slider’s flying performance and off-track capability, causing an increase in side reading and writing, and thus reduces the achievable recording density. Large skewed actuation also complicates the position error signal calibration process in the hard disk drive servo loop. This paper presents a 4 link mechanism which can be designed to achieve near zero skew actuation in hard disk drives. The profiles of the arm, suspension, and links can be designed and optimized such that the skew angle is close to zero while the VCM actuator rotates from the ID to the OD. Study shows that the 4-link mechanism does not degrade the resonance performance along the tracking direction compared to a conventional actuator.
Tumor-Associated Immune Parameters for Personalized Patient Care
Authors: Pagès Franck
Published: December 2013

Techniques are needed to measure clinically useful immune parameters that predict tumor prognosis and specify personalized therapies.
Protecting Research and a Case for Optimism
Authors: Gates Bill
Published: December 2013

This Editorial is based on the David E. Barmes Global Health Lecture delivered at the NIH on 2 December 2013.
Large hepatic adenoma in a 21-year-old male
Authors: Martinez-Mier Gustavo , Enriquez De los Santos Horacio , Grube-Pagola Peter
Published: December 2013

Hepatic adenoma is an uncommon benign lesion of the liver that occurs more frequently in women in their third and fourth decades. The female/male ratio is up to 11:1. Hepatic adenomas may be single or multiple occasionally reaching sizes up to 20 cm. They are non-cancerous lesions, however they can become malignant. We present a 21-year-old male patient with no medical history who presented with abdominal pain, a palpable abdominal mass, abnormal liver function tests and a 14 kg weight loss in a 2-year period. A CT scan was performed with a 17 cm tumour compressing intrahepatic bile ducts. The patient underwent a right hepatectomy with no complications. Histopathological analysis of the tumour revealed a hepatic adenoma with central necrosis. The patient is asymptomatic at 1-year follow-up.
Socioeconomic inequalities in youth smoking in Brazil
Authors: Barreto Sandhi Maria , de Figueiredo Roberta Carvalho , Giatti Luana
Published: December 2013

Objective

The contribution of smoking to socioeconomic inequalities in health is increasing worldwide, including in Brazil. Youth smoking may play an important role in the increasing social inequalities related to smoking. This study investigates social determinants of smoking among 15-year-old to 19-year-old individuals.

Design

Cross-sectional study.

Setting

The study uses data of 3536 participants aged 15–19 years of age of the Global Adult Tobacco Survey (GATS) and the National Household Sample Survey (Pesquisa Nacional por Amostragem de Domicilio, PNAD) obtained from household interviews. Smoking was defined as currently smoking tobacco products, regardless of frequency. Household socioeconomic indicators included per capita income, the educational level and sex of the head of the household, the presence of smoking restrictions and the number of smokers (excluding adolescents). Adolescent social factors included years of delaying school and social status (full-time student, working, and neither working nor studying). The hierarchical logistic regression analysis considered the effect of the complex sampling design.

Results

From 3536 participants, 6.2% were smokers (95% CI 5.4 to 7.1). More men than women had the habit of smoking (7.2%; 5.9 to 8.6 vs 3.6%; 2.7 to 4.6). The likelihood of smoking was significantly greater for men and older teens. There was an upward trend in the OR of smoking according to the number of smokers in the house. Adolescents living in households with no smoking restrictions had a greater likelihood of being smokers. OR of smoking rose as the number of years of delaying school increased, being about three times greater among adolescents who were working and five times greater among those who were neither studying nor working.

Conclusions

Results demonstrate that socioeconomic inequality in smoking is established at younger ages and that school delay as well as school abandonment may contribute to increased smoking-related inequalities. Smoking restrictions at home were protective against adolescents becoming smokers. Living with other smokers was a strong predictor of adolescents becoming smokers.
Education level and survival after oesophageal cancer surgery: a prospective population-based cohort study
Authors: Brusselaers Nele , Ljung Rickard , Mattsson Fredrik , Johar Asif , Wikman Anna , Lagergren Pernilla , Lagergren Jesper
Published: December 2013

Objectives

This study aimed to investigate whether a higher education level is associated with an improved long-term survival after oesophagectomy for cancer.

Design

A prospective, population-based cohort study.

Setting

Sweden—nationwide.

Participants

90% of all patients with oesophageal and cardia cancer who underwent a resection in Sweden in 2001–2005 were enrolled in this study (N=600; 80.3% male) and followed up until death or the end of the study period (2012). The study exposure was level of education, defined as compulsory (≤9 years), moderate (10–12 years) or high (≥13 years).

Outcome measures

The main outcome measure was overall 5-year survival after oesophagectomy. Cox regression was used to estimate the associations between education level and mortality, expressed as HRs with 95% CIs, with adjustment for sex, age, tumour stage, histological type, complications, comorbidities and annual surgeon volume. The patient group with highest education was used as the reference category.

Results

Among the 600 included patients, 281 (46.8%) had compulsory education, 238 (39.7%) had moderate education and 81 (13.5%) had high education. The overall 5-year survival rate was 23.1%, 24.4% and 32.1% among patients with compulsory, moderate and high education, respectively. After adjustment for confounders, a slightly higher, yet not statistically significantly increased point HR was found among the compulsory educated patients (HR 1.08, 95% CI 0.80 to 1.47). In patients with tumour stage IV, increased adjusted HRs were found for compulsory (HR 2.88, 95% CI 1.07 to 7.73) and moderately (HR 2.83, 95% CI 1.15 to 6.95) educated patients. No statistically significant associations were found for the other tumour stages.

Conclusions

This study provides limited evidence of an association between lower education and worse long-term survival after oesophagectomy for cancer.
Epidemiology and genetics of common mental disorders in the general population: the PEGASUS-Murcia project
Authors: Navarro-Mateu Fernando , Tormo MJ , Vilagut G , Alonso J , Ruíz-Merino G , Escámez T , Salmerón D , Júdez J , Martínez S , Navarro C
Published: December 2013

Background

Multidisciplinary collaboration between clinicians, epidemiologists, neurogeneticists and statisticians on research projects has been encouraged to improve our knowledge of the complex mechanisms underlying the aetiology and burden of mental disorders. The PEGASUS-Murcia (Psychiatric Enquiry to General Population in Southeast Spain-Murcia) project was designed to assess the prevalence of common mental disorders and to identify the risk and protective factors, and it also included the collection of biological samples to study the gene–environmental interactions in the context of the World Mental Health Survey Initiative.

Methods and analysis

The PEGASUS-Murcia project is a new cross-sectional face-to-face interview survey based on a representative sample of non-institutionalised adults in the Region of Murcia (Mediterranean Southeast, Spain). Trained lay interviewers used the latest version of the computer-assisted personal interview of the Composite International Diagnostic Interview (CIDI 3.0) for use in Spain, specifically adapted for the project. Two biological samples of buccal mucosal epithelium will be collected from each interviewed participant, one for DNA extraction for genomic and epigenomic analyses and the other to obtain mRNA for gene expression quantification. Several quality control procedures will be implemented to assure the highest reliability and validity of the data. This article describes the rationale, sampling methods and questionnaire content as well as the laboratory methodology.

Ethics and dissemination

Informed consent will be obtained from all participants and a Regional Ethics Research Committee has approved the protocol. Results will be disseminated in peer-reviewed publications and presented at the national and the international conferences.

Discussion

Cross-sectional studies, which combine detailed personal information with biological data, offer new and exciting opportunities to study the gene–environmental interactions in the aetiology of common mental disorders in representative samples of the general population. A collaborative multidisciplinary research approach offers the potential to advance our knowledge of the underlying complex interactions and this opens the field for further innovative study designs in psychiatric epidemiology.
Firearms and suicide in US cities
Authors: Miller Matthew , Warren Molly , Hemenway David , Azrael Deborah
Published: December 2013

On an average day in the USA more than 100 Americans die by suicide—half use firearms. Suicide rates overall and by firearms are higher, on average, in states where household firearm ownership is more common. In general this means in states where a greater proportion of the population lives in rural areas. The current ecological study focuses on the relation between measures of household firearm prevalence and suicide mortality in urban areas (metropolitan statistical areas and divisions) using survey-based measures of firearm ownership. Suicide rates (1999–2010) for metropolitan statistical areas that are comprised of large US cities come from death certificate records; rates of household firearm ownership come from the 2002 and 2004 Behavioural Risk Factor Surveillance System. Higher rates of firearm ownership are strongly associated with higher rates of overall suicide and firearm suicide, but not with non-firearm suicide. Stratification by gender, age and race did not materially affect the association between firearms and suicide. This study provides evidence consistent with previous case–control work and extends evidence from previous state- and region-level ecological studies that firearms in the home impose suicide risk above and beyond baseline.
Changes in household, transport and recreational physical activity and television viewing time across the transition to retirement: longitudinal evidence from the EPIC-Norfolk cohort
Authors: Barnett Inka , van Sluijs Esther , Ogilvie David , Wareham Nicholas J
Published: December 2013

Background

Retirement is associated with an increase in recreational physical activity but its impact on other domains of activity (at home, for transport) and sedentary behaviour, such as time spent watching television (TV) is unknown. We examined the association between retirement and changes in domain-specific and overall activity and TV viewing.

Methods

Data were derived from the population-based EPIC (European Prospective Investigation into Cancer)–Norfolk cohort. Physical activity and TV viewing time were self-reported at baseline (1997–2000) and follow-up 2 (2006–2007) by 3334 participants employed at baseline, of whom 785 (24%) were retired at follow-up 1 (2002–2006). Multivariable regression models were fitted to estimate the association between retirement and changes in physical activity and weekly TV viewing time.

Results

Compared with continued employment, retirement was associated with a decline in overall activity (men: non-manual, −40.9 MET h/wk; manual, −49.6 MET h/wk; women: non-manual, −26.9 MET h/wk; manual, −31.6 MET h/wk; all p<0.001 (MET, metabolic equivalent of task)). Domain-specific activity declined for transport and occupational (p<0.001) and increased for recreational (p<0.02) and household (p≤0.002) activity. We observed significant interaction between retirement and social class in respect of overall and domain-specific activity apart from household activity. Retirement was associated with a mean increase in TV viewing time, with the largest increase among manual social classes (men: +3.9 h/wk; women: +2.8 h/wk; both p<0.001).

Conclusions

Interventions should aim to promote household and transport as well as recreational activity. Further research on the impact of retirement on sedentary behaviour is needed.
NONAUTONOMOUS DARK SOLITONS IN BOSE–EINSTEIN CONDENSATE
Authors: XIE WEI-DONG , YE FAN , HE WANFEN , FENG SHUO , ZHANG LI
Published: December 2013

In this paper, we study on dark solitons of Bose–Einstein condensate analytically in a time-dependent harmonic trap with an arbitrary time-dependent linear potential and complex potential. It is shown that the nonautonomous dark soliton can be manipulated well through managing external potentials and nonlinear interaction between atoms. We believe that these results would stimulate experiments to manage dark solitons.
CARRIER–LATTICE RELAXATION FOR BROADENING EPR LINEWIDTH IN Nd0.55Sr0.45MnO3
Authors: FAN JIYU , ZHANG XIYUAN , TONG WEI , ZHANG LEI , ZHANG WEICHUN , ZHU YAN , SHI YANGGUANG , HU DAZHI , HONG BO , YING YAO , LING LANGSHENG , PI LI , ZHANG YUHENG
Published: December 2013

In this paper, we report the electron paramagnetic resonance (EPR) study of perovskite manganite Nd 0.55 Sr 0.45 MnO 3. Experimental data reveal that the EPR linewidth broadens with a quasilinear manner up to 480 K. The broadening of the EPR linewidth can be understood in terms of the shortening of carrier–lattice relaxation time due to the occurrence of strong carrier–phonon interactions. Two same activation energies obtained respectively from the temperature dependence of EPR intensity and resistivity indicate that the linewidth variation is correlated to the small polaron hopping. Therefore, the carrier–lattice coupling play a major role for deciding its magnetism in the present system.
LOCAL MAGNETIC BEHAVIOR OF54FeinEuFe2As2ANDEu0.5K0.5Fe2As2: MICROSCOPIC STUDY USING TIME DIFFERENTIAL PERTURBED ANGULAR DISTRIBUTION (TDPAD) SPECTROSCOPY
Authors: MOHANTA S. K. , MISHRA S. N. , DAVANE S. M. , LAYEK S. , HOSSAIN Z.
Published: December 2013

In this paper, we report the time differential perturbed angular distribution measurements of54Fe on a polycrystalline EuFe2As2and Eu0.5K0.5Fe2As2. The hyperfine field and nuclear spin-relaxation rate are strongly temperature dependent in the paramagnetic state suggesting strong spin fluctuation in the parent compound. The local susceptibility show Curie–Weiss-like temperature dependence and Korringa-like relaxation in the tetragonal phase indicating the presence of local moment. In the orthorhombic phase, the hyperfine field behavior suggesting quasi two-dimensional magnetic ordering. The experimental results are in a good agreement with first-principle calculations based on density functional theory.
Most Tensor Problems Are NP-Hard
Authors: Hillar Christopher J. , Lim Lek-Heng
Published: December 2013

We prove that multilinear (tensor) analogues of many efficiently computable problems in numerical linear algebra are NP-hard. Our list includes: determining the feasibility of a system of bilinear equations, deciding whether a 3-tensor possesses a given eigenvalue, singular value, or spectral norm; approximating an eigenvalue, eigenvector, singular vector, or the spectral norm; and determining the rank or best rank-1 approximation of a 3-tensor. Furthermore, we show that restricting these problems to symmetric tensors does not alleviate their NP-hardness. We also explain how deciding nonnegative definiteness of a symmetric 4-tensor is NP-hard and how computing the combinatorial hyperdeterminant is NP-, #P-, and VNP-hard.
Improving Text Classification Accuracy by Training Label Cleaning
Authors: Esuli Andrea , Sebastiani Fabrizio
Published: December 2013

In text classification (TC) and other tasks involving supervised learning, labelled data may be scarce or expensive to obtain. Semisupervised learning and active learning are two strategies whose aim is maximizing the effectiveness of the resulting classifiers for a given amount of training effort. Both strategies have been actively investigated for TC in recent years. Much less research has been devoted to a third such strategy,
training label cleaning
(TLC), which consists in devising ranking functions that sort the original training examples in terms of how likely it is that the human annotator has mislabelled them. This provides a convenient means for the human annotator to revise the training set so as to improve its quality. Working in the context of boosting-based learning methods for multilabel classification we present three different techniques for performing TLC and, on three widely used TC benchmarks, evaluate them by their capability of spotting training documents that, for experimental reasons only, we have purposefully mislabelled. We also evaluate the degradation in classification effectiveness that these mislabelled texts bring about, and to what extent training label cleaning can prevent this degradation.
Efficient Video Stream Monitoring for Near-Duplicate Detection and Localization in a Large-Scale Repository
Authors: Chiu Chih-Yi , Tsai Tsung-Han , Han Guei-Wun , Hsieh Cheng-Yu , Li Sheng-Yang
Published: December 2013

In this article, we study the efficiency problem of video stream near-duplicate monitoring in a large-scale repository. Existing stream monitoring methods are mainly designed for a short video to scan over a query stream; they have difficulty being scalable for a large number of long videos. We present a simple but effective algorithm called incremental similarity update to address the problem. That is, a similarity upper bound between two videos can be calculated incrementally by leveraging the prior knowledge of the previous calculation. The similarity upper bound takes a lightweight computation to filter out unnecessary time-consuming computation for the actual similarity between two videos, making the search process more efficient. We integrate the algorithm with inverted indexing to obtain a candidate list from the repository for the given query stream. Meanwhile, the algorithm is applied to scan each candidate for locating exact near-duplicate subsequences. We implement several state-of-the-art methods for comparison in terms of accuracy, execution time, and memory consumption. Experimental results demonstrate the proposed algorithm yields comparable accuracy, compact memory size, and more efficient execution time.
From Low-Distortion Norm Embeddings to Explicit Uncertainty Relations and Efficient Information Locking
Authors: Fawzi Omar , Hayden Patrick , Sen Pranab
Published: December 2013

The existence of quantum uncertainty relations is the essential reason that some classically unrealizable cryptographic primitives become realizable when quantum communication is allowed. One operational manifestation of these uncertainty relations is a purely quantum effect referred to as
information locking
[DiVincenzo et al. 2004]. A locking scheme can be viewed as a cryptographic protocol in which a uniformly random
n
-bit message is encoded in a quantum system using a classical key of size much smaller than
n
. Without the key, no measurement of this quantum state can extract more than a negligible amount of information about the message, in which case the message is said to be “locked”. Furthermore, knowing the key, it is possible to recover, that is “unlock”, the message.

In this article, we make the following contributions by exploiting a connection between uncertainty relations and low-distortion embeddings of Euclidean spaces into slightly larger spaces endowed with the ℓ
1
norm. We introduce the notion of a
metric uncertainty relation
and connect it to low-distortion embeddings of ℓ
2
into ℓ
1
. A metric uncertainty relation also implies an entropic uncertainty relation. We prove that random bases satisfy uncertainty relations with a stronger definition and better parameters than previously known. Our proof is also considerably simpler than earlier proofs. We then apply this result to show the existence of locking schemes with key size independent of the message length. Moreover, we give
efficient
constructions of bases satisfying metric uncertainty relations. The bases defining these metric uncertainty relations are computable by quantum circuits of almost linear size. This leads to the first explicit construction of a strong information locking scheme. These constructions are obtained by adapting an explicit norm embedding due to Indyk [2007] and an extractor construction of Guruswami et al. [2009]. We apply our metric uncertainty relations to exhibit communication protocols that perform equality testing of
n
-qubit states. We prove that this task can be performed by a single message protocol using
O
(log
2
n
) qubits and
n
bits of communication, where the computation of the sender is efficient.
Least upper bounds on the size of confluence and church-rosser diagrams in term rewriting and λ-calculus
Authors: Ketema Jeroen , Simonsen Jakob Grue
Published: December 2013

We study confluence and the Church-Rosser property in term rewriting and λ-calculus with explicit bounds on term sizes and reduction lengths. Given a system
R
, we are interested in the lengths of the reductions in the smallest valleys
t
→ *
s
′ * ←
t
′ expressed as a function:

—for confluence a function vs

R

(
m
,
n
) where the valleys are for peaks
t
←
s
→ *
t
′ with
s
of size at most
m
and the reductions of maximum length
n
, and

—for the Church-Rosser property a function cvs

R

(
m
,
n
) where the valleys are for conversions
t
↔ *
t
′ with
t
and
t
′ of size at most
m
and the conversion of maximum length
n
.

For confluent Term Rewriting Systems (TRSs), we prove that vs

R

is a total computable function, and for linear such systems that cvs

R

is a total computable function. Conversely, we show that every total computable function is the lower bound on the functions vs

R

(
m
,
n
) and cvs

R

(
m
,
n
) for some TRS
R
: In particular, we show that for every total computable function φ: N → N there is a TRS
R
with a single term
s
such that vs

R

(|
s
|,
n
) ≥ φ(
n
) and cvs

R

(
n
,
n
) ≥ φ(
n
) for all
n
. For orthogonal TRSs
R
we prove that there is a constant
k
such that: (a) vs

R

(
m
,
n
) is bounded from above by a function exponential in
k
and (b) cvs

R

(
m
,
n
) is bounded from above by a function in the fourth level of the Grzegorczyk hierarchy. Similarly, for λ-calculus, we show that vs

R

(
m
,
n
) is bounded from above by a function in the fourth level of the Grzegorczyk hierarchy.
Verification of linear duration properties over continuous-time markov chains
Authors: Chen Taolue , Diciolla Marco , Kwiatkowska Marta , Mereacre Alexandru
Published: December 2013

Stochastic modelling and algorithmic verification techniques have been proved useful in analysing and detecting unusual trends in performance and energy usage of systems such as power management controllers and wireless sensor devices. Many important properties are dependent on the cumulated time that the device spends in certain states, possibly intermittently. We study the problem of verifying
continuous-time Markov Chains
(CTMCs) against
Linear Duration Properties
(LDP), that is, properties stated as conjunctions of linear constraints over the total duration of time spent in states that satisfy a given property. We identify two classes of LDP properties,
Eventuality Duration Properties
(EDP) and
Invariance Duration Properties
(IDP), respectively referring to the reachability of a set of goal states, within a time bound; and the continuous satisfaction of a duration property over an execution path. The central question that we address is how to compute the probability of the set of infinite timed paths of the CTMC that satisfy a given LDP. We present algorithms to approximate these probabilities up to a given precision, stating their complexity and error bounds. The algorithms mainly employ an adaptation of uniformisation and the computation of volumes of multidimensional integrals under systems of linear constraints, together with different mechanisms to bound the errors.
Investigating Users’ Perspectives of Web Single Sign-On
Authors: Sun San-Tsai , Pospisil Eric , Muslukhov Ildar , Dindar Nuray , Hawkey Kirstie , Beznosov Konstantin
Published: December 2013

OpenID and OAuth are open and simple Web SSO protocols that have been adopted by major service providers, and millions of supporting Web sites. However, the average user’s perception of Web SSO is still poorly understood. Through several user studies, this work investigates users’ perceptions and concerns when using Web SSO for authentication. We found that our participants had several misconceptions and concerns that impeded their adoption. This ranged from their inadequate mental models of Web SSO, to their concerns about personal data exposure, and a reduction in perceived Web SSO value due to the employment of password management practices. Informed by our findings, we offer a Web SSO technology acceptance model, and suggest design improvements.
Tractable Hypergraph Properties for Constraint Satisfaction and Conjunctive Queries
Authors: Marx Dániel
Published: December 2013

An important question in the study of constraint satisfaction problems (CSP) is understanding how the graph or hypergraph describing the incidence structure of the constraints influences the complexity of the problem. For binary CSP instances (that is, where each constraint involves only two variables), the situation is well understood: the complexity of the problem essentially depends on the treewidth of the graph of the constraints [Grohe 2007; Marx 2010b]. However, this is not the correct answer if constraints with unbounded number of variables are allowed, and in particular, for CSP instances arising from query evaluation problems in database theory. Formally, if
H
is a class of hypergraphs, then let CSP(
H
) be CSP restricted to instances whose hypergraph is in
H
. Our goal is to characterize those classes of hypergraphs for which CSP(
H
) is polynomial-time solvable or fixed-parameter tractable, parameterized by the number of variables. Note that in the applications related to database query evaluation, we usually assume that the number of variables is much smaller than the size of the instance, thus parameterization by the number of variables is a meaningful question.

The most general known property of
H
that makes CSP(
H
) polynomial-time solvable is bounded fractional hypertree width. Here we introduce a new hypergraph measure called
submodular width
, and show that bounded submodular width of
H
(which is a strictly more general property than bounded fractional hypertree width) implies that CSP(
H
) is fixed-parameter tractable. In a matching hardness result, we show that if
H
has unbounded submodular width, then CSP(
H
) is not fixed-parameter tractable (and hence not polynomial-time solvable), unless the Exponential Time Hypothesis (ETH) fails. The algorithmic result uses tree decompositions in a novel way: instead of using a single decomposition depending on the hypergraph, the instance is split into a set of instances (all on the same set of variables as the original instance), and then the new instances are solved by choosing a different tree decomposition for each of them. The reason why this strategy works is that the splitting can be done in such a way that the new instances are “uniform” with respect to the number extensions of partial solutions, and therefore the number of partial solutions can be described by a submodular function. For the hardness result, we prove via a series of combinatorial results that if a hypergraph
H
has large submodular width, then a 3SAT instance can be efficiently simulated by a CSP instance whose hypergraph is
H
. To prove these combinatorial results, we need to develop a theory of (multicommodity) flows on hypergraphs and vertex separators in the case when the function
b
(
S
) defining the cost of separator
S
is submodular, which can be of independent interest.
Tensor-Rank and Lower Bounds for Arithmetic Formulas
Authors: Raz Ran
Published: December 2013

We show that any explicit example for a tensor
A
: [
n
]
r
→
F
with tensor-rank ≥
n
rċ(1−o(1))
, where
r
=
r
(
n
) ≤ log
n
/log log
n
is super-constant, implies an explicit super-polynomial lower bound for the size of general arithmetic formulas over F. This shows that strong enough lower bounds for the size of arithmetic formulas of depth 3 imply super-polynomial lower bounds for the size of general arithmetic formulas.

One component of our proof is a new approach for homogenization and multilinearization of arithmetic formulas, that gives the following results:

We show that for any
n
-variate homogeneous polynomial
f
of degree
r
, if there exists a (fanin-2) formula of size
s
and depth
d
for
f
then there exists a homogeneous formula of size
O
((
d
+
r
+1 r) ċ
s
) for
f
. In particular, for any
r
≤
O
(log
n
), if there exists a polynomial size formula for
f
then there exists a polynomial size homogeneous formula for
f
. This refutes a conjecture of Nisan and Wigderson [1996] and shows that super-polynomial lower bounds for homogeneous formulas for polynomials of small degree imply super-polynomial lower bounds for general formulas.

We show that for any
n
-variate set-multilinear polynomial
f
of degree
r
, if there exists a (fanin-2) formula of size
s
and depth
d
for
f
, then there exists a set-multilinear formula of size
O
((
d
+ 2)
r
ċ
s
) for
f
. In particular, for any
r
≤
O
(log
n
/log log
n
), if there exists a polynomial size formula for
f
then there exists a polynomial size set-multilinear formula for
f
. This shows that super-polynomial lower bounds for set-multilinear formulas for polynomials of small degree imply super-polynomial lower bounds for general formulas.
Fidelity, Soundness, and Efficiency of Interleaved Comparison Methods
Authors: Hofmann Katja , Whiteson Shimon , Rijke Maarten De
Published: December 2013

Ranker evaluation is central to the research into search engines, be it to compare rankers or to provide feedback for learning to rank. Traditional evaluation approaches do not scale well because they require explicit relevance judgments of document-query pairs, which are expensive to obtain. A promising alternative is the use of
interleaved comparison
methods, which compare rankers using click data obtained when interleaving their rankings.

In this article, we propose a framework for analyzing interleaved comparison methods. An interleaved comparison method has
fidelity
if the expected outcome of ranker comparisons properly corresponds to the true relevance of the ranked documents. It is
sound
if its estimates of that expected outcome are unbiased and consistent. It is
efficient
if those estimates are accurate with only little data.

We analyze existing interleaved comparison methods and find that, while sound, none meet our criteria for fidelity. We propose a
probabilistic interleave
method, which is sound and has fidelity. We show empirically that, by marginalizing out variables that are known, it is more efficient than existing interleaved comparison methods. Using importance sampling we derive a sound extension that is able to reuse historical data collected in previous comparisons of other ranker pairs.
Algebra, proof theory and applications for an intuitionistic logic of propositions, actions and adjoint modal operators
Authors: Dyckhoff Roy , Sadrzadeh Mehrnoosh , Truffaut Julien
Published: December 2013

We develop a cut-free nested sequent calculus as basis for a proof search procedure for an intuitionistic modal logic of actions and propositions. The actions act on propositions via a dynamic modality (the
weakest precondition
of program logics), whose left adjoint we refer to as “update” (the
strongest postcondition
). The logic has agent-indexed adjoint pairs of epistemic modalities: the left adjoints encode agents' uncertainties and the right adjoints encode their beliefs. The rules for the “update” modality encode learning as a result of discarding uncertainty. We prove admissibility of
Cut
, and hence the soundness and completeness of the logic with respect to an algebraic semantics. We interpret the logic on epistemic scenarios that consist of honest and dishonest communication actions, add assumption rules to encode them, and prove that the calculus with the assumption rules still has the admissibility results. We apply the calculus to encode (and allow reasoning about) the classic epistemic puzzles of
dirty children
(a.k.a. “muddy children”) and
drinking logicians
and some versions with dishonesty or noise; we also give an application where the actions are movements of a robot rather than announcements.
Suppression of the mTORC1/STAT3/Notch1 pathway by activated AMPK prevents hepatic insulin resistance induced by excess amino acids
Authors: Li Hongliang , Lee Jiyeon , He Chaoyong , Zou Ming-Hui , Xie Zhonglin
Published: December 2013

Nutrient overload is associated with the development of obesity, insulin resistance, and type 2 diabetes. However, the underlying mechanisms for developing insulin resistance in the presence of excess nutrients are incompletely understood. We investigated whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic insulin resistance that is induced by the consumption of a high-protein diet (HPD) and the presence of excess amino acids. Exposure of HepG2 cells to excess amino acids reduced AMPK phosphorylation, upregulated Notch1 expression, and impaired the insulin-stimulated phosphorylation of Akt Ser473 and insulin receptor substrate-1 (IRS-1) Tyr612. Inhibition of Notch1 prevented amino acid-induced insulin resistance, which was accompanied by reduced expression of Rbp-Jk, hairy and enhancer of split-1, and forkhead box O1. Mechanistically, mTORC1 signaling was activated by excess amino acids, which then positively regulated Notch1 expression through the activation of the signal transducer and activator of transcription 3 (STAT3). Activation of AMPK by metformin inhibited mTORC1-STAT3 signaling, thereby preventing excess amino acid-impaired insulin signaling. Finally, HPD feeding suppressed AMPK activity, activated mTORC1/STAT3/Notch1 signaling, and induced insulin resistance. Chronic administration of either metformin or rapamycin inhibited the HPD-activated mTORC1/STAT3/Notch1 signaling pathway and prevented hepatic insulin resistance. We conclude that the upregulation of Notch1 expression by hyperactive mTORC1 signaling is an essential event in the development of hepatic insulin resistance in the presence of excess amino acids. Activation of AMPK prevents amino acid-induced insulin resistance through the suppression of the mTORC1/STAT3/Notch1 signaling pathway.
Contributions of adipose tissue architectural and tensile properties toward defining healthy and unhealthy obesity
Authors: Lackey Denise E. , Burk David H. , Ali Mohamed R. , Mostaedi Rouzbeh , Smith William H. , Park Jiyoung , Scherer Philipp E. , Seay Shundra A. , McCoin Colin S. , Bonaldo Paolo , Adams Sean H.
Published: December 2013

The extracellular matrix (ECM) plays an important role in the maintenance of white adipose tissue (WAT) architecture and function, and proper ECM remodeling is critical to support WAT malleability to accomodate changes in energy storage needs. Obesity and adipocyte hypertrophy place a strain on the ECM remodeling machinery, which may promote disordered ECM and altered tissue integrity and could promote proinflammatory and cell stress signals. To explore these questions, new methods were developed to quantify omental and subcutaneous WAT tensile strength and WAT collagen content by three-dimensional confocal imaging, using collagen VI knockout mice as a methods validation tool. These methods, combined with comprehensive measurement of WAT ECM proteolytic enzymes, transcript, and blood analyte analyses, were used to identify unique pathophenotypes of metabolic syndrome and type 2 diabetes mellitus in obese women, using multivariate statistical modeling and univariate comparisons with weight-matched healthy obese individuals. In addition to the expected differences in inflammation and glycemic control, approximately 20 ECM-related factors, including omental tensile strength, collagen, and enzyme transcripts, helped discriminate metabolically compromised obesity. This is consistent with the hypothesis that WAT ECM physiology is intimately linked to metabolic health in obese humans, and the studies provide new tools to explore this relationship.
Sulfation of 25-hydroxycholesterol regulates lipid metabolism, inflammatory responses, and cell proliferation
Authors: Ren Shunlin , Ning Yanxia
Published: December 2013

Intracellular lipid accumulation, inflammatory responses, and subsequent apoptosis are the major pathogenic events of metabolic disorders, including atherosclerosis and nonalcoholic fatty liver diseases. Recently, a novel regulatory oxysterol, 5-cholesten-3b, 25-diol 3-sulfate (25HC3S), has been identified, and hydroxysterol sulfotransferase 2B1b (SULT2B1b) has been elucidated as the key enzyme for its biosynthesis from 25-hydroxycholesterol (25HC) via oxysterol sulfation. The product 25HC3S and the substrate 25HC have been shown to coordinately regulate lipid metabolism, inflammatory responses, and cell proliferation in vitro and in vivo. 25HC3S decreases levels of the nuclear liver oxysterol receptor (LXR) and sterol regulatory element-binding proteins (SREBPs), inhibits SREBP processing, subsequently downregulates key enzymes in lipid biosynthesis, decreases intracellular lipid levels in hepatocytes and THP-1-derived macrophages, prevents apoptosis, and promotes cell proliferation in liver tissues. Furthermore, 25HC3S increases nuclear PPARγ and cytosolic IκBα and decreases nuclear NF-κB levels and proinflammatory cytokine expression and secretion when cells are challenged with LPS and TNFα. In contrast to 25HC3S, 25HC, a known LXR ligand, increases nuclear LXR and decreases nuclear PPARs and cytosol IκBα levels. In this review, we summarize our recent findings, including the discovery of the regulatory oxysterol sulfate, its biosynthetic pathway, and its functional mechanism. We also propose that oxysterol sulfation functions as a regulatory signaling pathway.
Pre-suckling calcium supplementation effectively prevents lactation-induced osteopenia in rats
Authors: Suntornsaratoon Panan , Kraidith Kamonshanok , Teerapornpuntakit Jarinthorn , Dorkkam Nitita , Wongdee Kannikar , Krishnamra Nateetip , Charoenphandhu Narattaphol
Published: December 2013

During lactation, osteoclast-mediated bone resorption and intestinal calcium hyperabsorption help provide extra calcium for lactogenesis. Since the suckling-induced surge of pituitary prolactin (PRL) rapidly stimulates calcium absorption in lactating rats, it is hypothesized that pre-suckling oral calcium supplementation should be an efficient regimen to shift the calcium source from bone to diet, thereby slowing lactation-induced osteopenia. Our results showed that 30-min suckling markedly stimulated maternal duodenal calcium transport, which returned to the baseline at 45 min. Lactating rats given 4 mg/kg per dose calcium via a gavage tube at 90 min pre-suckling 4 doses a day for 14 days prevented a decrease in bone mineral density (BMD) of long bones and vertebrae. On the other hand, a single-dose supplementation, despite the same amount of calcium per day, appeared less effective. Because glucose and galactose further stimulated duodenal calcium transport in lactating rats, pre-suckling calcium supplement containing both sugars successfully normalized plasma ionized calcium and led to better bone gain than that with calcium alone. A histomorphometric study revealed that lactating rats given pre-suckling calcium plus monosaccharide supplement manifested greater trabecular bone volume and thickness and exhibited less eroded surface than in vehicle-treated lactating rats. Beneficial effects of the 14-day calcium supplementation persisted until 6 mo postweaning in dams and also elevated the baseline BMD of the offspring. In conclusion, our proof-of-concept study has corroborated that pre-suckling calcium supplements, especially regimens containing monosaccharides, are efficient in preventing osteopenia in lactating rats and could increase bone density in both breastfeeding mothers and neonates.