bluuebunny/crossref_metadata_2025 huggingface dataset:
How do patients conceptualize chronic obstructive pulmonary disease?
Authors: Goldman RE , Mennillo L , Stebbins P , Parker DR
Published: August 2017

Chronic obstructive pulmonary disease (COPD) is a leading cause of death in the United States, yet even at risk or diagnosed patients misunderstand COPD and its consequences for their quality of life and mortality. This study explored how patients conceptualize the causes, symptoms, consequences, treatment, and risk for developing COPD. The study consisted of six focus groups: 39 participants who were adults > 40 and current smoker or have COPD symptoms, family history, or exposures. Although many participants had some familiarity with the breathing, lung function, physical, emotional, and social consequences of COPD, confusion and misunderstanding prevailed. Few knew that COPD, chronic bronchitis, and emphysema are synonymous. Some participants claimed that they “only” had bronchitis and/or emphysema and not COPD. Some participants described behavioral adaptations to decrease symptom impact and others expressed strong interest in learning how to increase daily functioning. Insufficient knowledge and persisting misconceptions about COPD can prevent patients from accessing life-enhancing strategies. Patients can benefit from (1) providers clarifying COPD’s connection to chronic bronchitis and emphysema to aid them in recognizing the need for mitigating action; (2) encouraging smoking cessation, specifically to stem worsening of disease; and (3) explaining lifestyle adaptations for easing daily life despite decreased lung function.
Security analysis and enhancements of an improved multi-factor biometric authentication scheme
Authors: Park YoHan , Park KiSung , Lee KyungKeun , Song Hwangjun , Park YoungHo
Published: August 2017

Many remote user authentication schemes have been designed and developed to establish secure and authorized communication between a user and server over an insecure channel. By employing a secure remote user authentication scheme, a user and server can authenticate each other and utilize advanced services. In 2015, Cao and Ge demonstrated that An’s scheme is also vulnerable to several attacks and does not provide user anonymity. They also proposed an improved multi-factor biometric authentication scheme. However, we review and cryptanalyze Cao and Ge’s scheme and demonstrate that their scheme fails in correctness and providing user anonymity and is vulnerable to ID guessing attack and server masquerading attack. To overcome these drawbacks, we propose a security-improved authentication scheme that provides a dynamic ID mechanism and better security functionalities. Then, we show that our proposed scheme is secure against various attacks and prove the security of the proposed scheme using BAN Logic.
The Headache Action Plan Project for Youth (HAPPY): School Nurses as Facilitators of System Change in Pediatric Migraine Care
Authors: Connelly Mark , Bickel Jennifer , Wingert Tammie , Galemore Cynthia
Published: August 2017

Migraine is a common health problem in youth that is ranked highest for disability among neurological conditions and is one of the leading reasons for school absences. Children with migraines frequently are seen by the school nurse for care, sometimes before ever being seen by another healthcare provider for evaluation and treatment. As such, school nurses have the unique opportunity to provide education and resources to children with migraines and their family. This article provides information on the Headache Action Plan Program for Youth (HAPPY), a project involving the provision of live and online migraine education and management resources to school nurses, children, families, and primary care providers in an effort to improve migraine recognition and care in the community.
Trust in Police Motivations During Involuntary Encounters
Authors: Novich Madeleine , Hunt Geoffrey
Published: August 2017

Problems related to distrust of police, including aggressive and prejudicial police behavior, continue to raise concerns. Using a procedural justice model, the present study examines perceptions of trust or the lack thereof among a subpopulation of young disadvantaged minority youth that routinely come in contact with the police: drug-dealing gang members. In this article, we examine 253 qualitative in-depth interviews comprised primarily of African American and Latino male and female drug-involved gang members, utilizing a comparative analysis, to examine how participants discuss interactions with law enforcement and describe situations where they trust the police or situations where they do not. The findings suggest that the context in which they were stopped operates as a primary differentiating component that shapes their perceptions of trust in the motivations behind police engagement. When stopped by the police for “justifiable” reasons, the participants expressed a trust in the motivations that necessitated the encounter. However, when stopped for reasons, which appeared as unreasonable, our participants voiced a strong sense of distrust in the motivations of the police. These findings suggest that procedural justice scholars should consider the extent to which the type or context of the encounter with the police plays an important role in influencing feelings of trust.
The Application of One-Hour Static Qigong Program to Decrease Needle Pain of Korean Adolescents With Type 1 Diabetes: A Randomized Crossover Design
Authors: Kim Euiyeon , Lee Ji-Eun , Sohn Min
Published: August 2017

The aim of this study was to describe application of a static Qigong program to decrease needle pain in Korean adolescents with type 1 diabetes and its pilot test results. The pilot study was a randomized crossover design including 26 adolescents randomized to Qigong or rest group. Participants received a 60-minute Qigong program consisted of warm up, deep breathing, imaginary, and a closing warm up. After 24-hour washout period, treatment assignments were switched. We collected before and after intervention using a self-administered questionnaire, which included the faces pain scale to assess expected and perceived pain during blood sugar testing and insulin injection and the Positive and Negative Affect Schedule. Only expected pain on insulin injection was significantly lower after intervention ( P = .025). The results suggested that the devised static Qigong program was feasible intervention to decrease at least expected pain on insulin injection of adolescents with type 1 diabetes.
Perfectionism and Life Narratives: A Qualitative Study
Authors: Farmer Julia R. , Mackinnon Sean P. , Cowie Megan
Published: August 2017

We examined how perfectionistic people conceptualize perfectionism and narrate life events using thematic analysis. Participants included 20 university students who qualified as highly perfectionistic based on cutoffs on the Almost Perfect Scale–Revised ( n = 6 adaptive, n = 14 maladaptive). Participants completed a qualitative interview. Using thematic analysis, we identified five themes regarding participants’ conceptualization of perfectionism. The most common themes supported prior theory (high personal standards, performance is never good enough), along with a few comparatively understudied themes (being neat and orderly, feels superior to others, gets caught up in the details). We also identified five themes in a life narrative interview (relationship success, relationship problems, agentic redemption, agentic contamination, and academic success), which provided insight into how young, perfectionistic university students create meaning and identity through autobiographical narratives. “Relationship success” themes were most central to adaptive perfectionists, whereas “agentic redemption” themes were most central to maladaptive perfectionists.
Does Operative or Nonoperative Treatment Achieve Better Results in A3 and A4 Spinal Fractures Without Neurological Deficit?
Authors: Rometsch Elke , Spruit Maarten , Härtl Roger , McGuire Robert Alton , Gallo-Kopf Brigitte Sandra , Kalampoki Vasiliki , Kandziora Frank
Published: August 2017

Study Design:

Systematic literature review with meta-analysis.

Objective:

Thoracolumbar (TL) fractures can be treated conservatively or surgically. Especially, the treatment strategy for incomplete and complete TL burst fractures (A3 and A4, AOSpine classification) in neurologically intact patients remains controversial. The aim of this work was to collate the clinical evidence on the respective treatment modalities.

Methods:

Searches were performed in PubMed and the Web of Science. Clinical and radiological outcome data were collected. For studies comparing operative with nonoperative treatment, the standardized mean differences (SMD) for disability and pain were calculated and methodological quality and risk of bias were assessed.

Results:

From 1929 initial matches, 12 were eligible. Four of these compared surgical with conservative treatment. A comparative analysis of radiological results was not possible due to a lack of uniform reporting. Differences in clinical outcomes at follow-up were small, both between studies and between treatment groups. The SMD was 0.00 (95% CI −0.072, 0.72) for disability and −0.05 (95% CI −0.91, 0.81) for pain. Methodological quality was high in most studies and no evidence of publication bias was revealed.

Conclusions:

We did not find differences in disability or pain outcomes between operative and nonoperative treatment of A3 and A4 TL fractures in neurologically intact patients. Notwithstanding, the available scores have been developed and validated for degenerative diseases; thus, their suitability in trauma may be questionable. Specific and uniform outcome parameters need to be defined and enforced for the evaluation of TL trauma.
Behaviour of ThSiO4 during hydrothermal alteration of
raremetal rich lithologies from peralkaline rocks
Authors: Macdonald R. , Bagiński B. , Kartashov P. M. , Zozulya D.
Published: August 2017

The behaviour of ThSiO4 during low-temperature alteration has
significance for element mobility and redistribution. Here we describe five
types of alteration of ThSiO4 by hydrothermal fluids: (1) primary
ThSiO4 associated with chevkinite-(Ce) in a quartz-epidote
metasomatite; (2) during alteration of monazite-(Ce) in a quartzolite; (3)
during alteration of fergusonite-(Y) in a quartz-epidote metasomatite; (4)
following exsolution from chevkinite-(Ce); and (5) associated with
cerite-(Ce) and with ilmenite and bastnäsite-(Ce) in late-stage veinlets in
a syenitic pegmatite and a metasomatite. The great majority of crystals have
been strongly altered compositionally, with variable degrees of replacement
of formula elements by non-formula elements, such as Ca, Fe, P and
REE. The most reliable geochemical indicators of
hydrothermal alteration are low analytical totals and non-stoichiometric
structural formulae. The alteration is variably ascribed to
dissolution-reprecipitation and pervasive fluid infiltration along cracks.
Thorium appears to have shown limited mobility in these samples.
Application of benchtop micro-XRF to geological
materials
Authors: Flude Stephanie , Haschke Michael , Storey Michael
Published: August 2017

Recent developments in X-ray optics have allowed the development of a range
of commercially available benchtop micro-XRF (μ-XRF) instruments that can
produce X-ray spot sizes of 20–30 μm on the sample, allowing major- and
trace-element analysis on a range of sample types and sizes with minimal
sample preparation. Such instruments offer quantitative analysis using
fundamental parameter based 'standardless' quantification algorithms. The
accuracy and precision of this quantitative analysis on geological
materials, and application of micro-XRF to wider geological problems is
assessed using a single benchtop micro-XRF instrument. Quantitative analysis
of internal reference materials and international standards shows that such
instruments can provide highly reproducible data but that, for many silicate
materials, standardless quantification is not accurate.Accuracy can be
improved, however, by using a simple type-calibration against a reference
material of similar matrix and composition. Qualitative analysis with
micro-XRF can simplify and streamline sample characterization and processing
for subsequent geochemical and isotopic analysis.
Embreyite: structure determination, chemical formula and comparative crystal chemistry
Authors: Kovrugin Vadim M. , Siidra Oleg I. , Pekov Igor V. , Chukanov Nikita V. , Khanin Dmitry A. , Agakhanov Atali A.
Published: August 2017

Embreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of microprobe analysis is Pb1.29Cu0.07Cr0.52P0.43O4(without taking into account the presence of H2O). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic,C2/m,a= 9.802(16),b= 5.603(9),c= 7.649(12) Å, β = 114.85(3)oandV= 381.2(11) Å3) has been solved by direct methods and refined toR1= 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in bothdvalues and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were re-calculated for the holotype sample using a new cell setting and correspondinghklindices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6distorted octahedra. The interlayer space is filled by disordered Pb2+and Cu2+cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O4]2]} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (Pbx$M_y^{2 +} $□1–x–y)2{Pb[(Cr,P)O4]2}(H2O)n, whereM2+= Cu and Zn and 0.5 ≤x+y≤ 1, or, in the simplified form: (Pb,Cu,□)2{Pb[(Cr,P)O4]2}(H2O)n. The simplified formula of embreyite is similar in stoichiometry to vauquelinite and may explain the existence of the solid-solution series. The determination of the crystal structure of embreyite may also help to resolve the crystal chemical nature of cassedanneite. The XRD pattern of cassedanneite contains a distinct reflection withd= 13.9 Å, forbidden for the embreyite unit cell. This feature may indicate the doubling of thecunit-cell parameter of cassedanneite in comparison with embreyite. We assume that cassedanneite has structural similarity to embreyite with, presumably, a disordered distribution of Cr and V.
Proteomic analysis of sputum reveals novel biomarkers for various presentations of asthma
Authors: Cao Chao , Li Wen , Hua Wen , Yan Fugui , Zhang Hao , Huang Huaqiong , Ying Yinghua , Li Na , Lan Fen , Wang Shaobin , Chen Xiao , Li Jing , Liu Jinkai , Lai Tianwen , Bao Zhengqiang , Cao Yuan , Zhao Yun , Huang Gang , Huang Lili , Huang Yaqing , Wu Ping , Peng Chao , Chen Zhihua , Chung Kian Fan , Zhong Nanshan , Ying Songmin , Shen Huahao
Published: August 2017

Background

It is now recognized that asthma
can present in different forms. Typically, asthma present with symptoms of wheeze, breathlessness and cough. Atypical forms of asthma such as cough variant asthma (CVA) or chest tightness variant asthma (CTVA) do not wheeze. We hypothesize that these different forms of asthma may have distinctive cellular and molecular features.

Methods

30 patients with typical or classical asthma (CA), 27 patients with CVA, 30 patients with CTVA, and 30 healthy control adults were enrolled in this prospective study. We measured serum IgE, lung function, sputum eosinophils, nitric oxide in exhaled breath (FeNO). We performed proteomic analysis of induced-sputum supernatants by mass spectrometry.

Results

There were no significant differences in atopy and FEV1 among patients with CA, CVA, and CTVA. Serum IgE, sputum eosinophil percentages, FeNO, anxiety and depression scores were significantly increased in the three presentations of asthmatic patients as compared with healthy controls but there was no difference between the asthmatic groups. Comprehensive mass spectrometric analysis revealed more than a thousand proteins in the sputum from patients with CA, CVA, and CTVA, among which 23 secreted proteins were higher in patients than that in controls.

Conclusions

Patients with CA, CVA, or CTVA share common clinical characteristics of eosinophilic airway inflammation. And more importantly, their sputum samples were composed with common factors with minor distinctions. These findings support the concept that these three different presentations of asthma have similar pathogenetic mechanism in terms of an enhanced Th2 associated with eosinophilia. In addition, this study identified a pool of novel biomarkers for diagnosis of asthma and to label its subtypes.

Trial registrationhttp://www.chictr.org.cn (ChiCTR-OOC-15006221)
Uncovering Capgras delusion using a large-scale medical records database
Authors: Bell Vaughan , Marshall Caryl , Kanji Zara , Wilkinson Sam , Halligan Peter , Deeley Quinton
Published: August 2017

Background

Capgras delusion is scientifically important but most commonly reported as single case studies. Studies analysing large clinical records databases focus on common disorders but none have investigated rare syndromes.

Aims

Identify cases of Capgras delusion and associated psychopathology, demographics, cognitive function and neuropathology in light of existing models.

Method

Combined computational data extraction and qualitative classification using 250 000 case records from South London and Maudsley Clinical Record Interactive Search (CRIS) database.

Results

We identified 84 individuals and extracted diagnosis-matched comparison groups. Capgras was not ‘monothematic’ in the majority of cases. Most cases involved misidentified family members or close partners but others were misidentified in 25% of cases, contrary to dual-route face recognition models. Neuroimaging provided no evidence for predominantly right hemisphere damage. Individuals were ethnically diverse with a range of psychosis spectrum diagnoses.

Conclusions

Capgras is more diverse than current models assume. Identification of rare syndromes complements existing ‘big data’ approaches in psychiatry.
Development and Validation of Nomograms Predictive of Overall and Progression-Free Survival in Patients With Oropharyngeal Cancer
Authors: Fakhry Carole , Zhang Qiang , Nguyen-Tân Phuc Felix , Rosenthal David I. , Weber Randal S. , Lambert Louise , Trotti Andy M. , Barrett William L. , Thorstad Wade L. , Jones Christopher U. , Yom Sue S. , Wong Stuart J. , Ridge John A. , Rao Shyam S.D. , Bonner James A. , Vigneault Eric , Raben David , Kudrimoti Mahesh R. , Harris Jonathan , Le Quynh-Thu , Gillison Maura L.
Published: August 2017

Purpose

Treatment of oropharyngeal squamous cell carcinoma (OPSCC) is evolving toward risk-based modification of therapeutic intensity, which requires patient-specific estimates of overall survival (OS) and progression-free survival (PFS).

Methods

To develop and validate nomograms for OS and PFS, we used a derivation cohort of 493 patients with OPSCC with known p16 tumor status (surrogate of human papillomavirus) and cigarette smoking history (pack-years) randomly assigned to clinical trials using platinum-based chemoradiotherapy (NRG Oncology Radiation Therapy Oncology Group [RTOG] 0129 and 0522). Nomograms were created from Cox models and internally validated by use of bootstrap and cross-validation. Model discrimination was measured by calibration plots and the concordance index. Nomograms were externally validated in a cohort of 153 patients with OPSCC randomly assigned to a third trial, NRG Oncology RTOG 9003.

Results

Both models included age, Zubrod performance status, pack-years, education, p16 status, and T and N stage; the OS model also included anemia and age × pack-years interaction; and the PFS model also included marital status, weight loss, and p16 × Zubrod interaction. Predictions correlated well with observed 2-year and 5-year outcomes. The uncorrected concordance index was 0.76 (95% CI, 0.72 to 0.80) for OS and 0.70 (95% CI, 0.66 to 0.74) for PFS, and bias-corrected indices were similar. In the validation set, OS and PFS models were well calibrated, and OS and PFS were significantly different across tertiles of nomogram scores (log-rank P = .003;< .001).

Conclusion

The validated nomograms provided useful prediction of OS and PFS for patients with OPSCC treated with primary radiation-based therapy.
Improving Access to Cancer Testing and Treatment in Kenya
Authors: Makau-Barasa Louise K. , Greene Sandra B. , Othieno-Abinya Nicholas A. , Wheeler Stephanie , Skinner Asheley , Bennett Antonia V.
Published: August 2017

Purpose

In response to the increasing cancer burden in Kenya, this study identified barriers to patients seeking access to cancer testing and treatment and to clinicians in delivering these services. Policy recommendations based on findings are presented.

Methods

This qualitative study used semistructured key informant interviews. Purposive sampling was used to recruit 14 participants: seven oncology clinicians and seven support and advocacy leaders for patients with cancer. Qualitative analysis was used to identify themes.

Results

Seven barriers to cancer testing and treatment were identified: high cost of testing and treatment, low level of knowledge about cancer among population and clinicians, poor health-seeking behaviors among population, long distances to access diagnostic and treatment services, lack of decentralized diagnostic and treatment facilities, poor communication, and lack of better cancer policy development and implementation.

Conclusion

Kenyans seeking cancer services face significant barriers that result in late presentation, misdiagnosis, interrupted treatment, stigma, and fear. Four policy recommendations to improve access for patients with cancer are (1) improve health insurance for patients with cancer; (2) establish testing and treatment facilities in all counties; (3) acquire diagnosis and treatment equipment and train health personnel to screen, diagnose, and treat cancer; and (4) increase public health awareness and education about cancer to improve diagnoses and treatment. Effective cancer testing and treatment options can be developed to address cancer in a resource-constrained environment like Kenya. An in-depth look at effective interventions and policies being implemented in countries facing similar challenges would provide valuable lessons to Kenya’s health sector and policymakers.
Mortality, Geriatric, and Nongeriatric Surgical Risk Factors Among the Eldest Old: A Prospective Observational Study
Authors: Pelavski Andres D. , De Miguel Marcos , Alcaraz Garcia-Tejedor Gabriela , Villarino Laura , Lacasta Albert , Señas Lucía , Rochera María I.
Published: August 2017

BACKGROUND:

Preoperative risk and postoperative outcomes among the elderly are the subject of extensive debate. However, the eldest old, that is, the fastest-growing and most vulnerable group, are insufficiently studied; even their mortality rate is unclear. This prospective observational study was performed with the aim of determining the mortality rate of this population and establishing which preoperative conditions were predictors of which postoperative outcomes. The study was undertaken between 2011 and 2015 in a major tertiary care university hospital.

METHODS:

All patients aged ≥85 years undergoing any elective procedure during the study period were included. Patients were followed up for 30 days postoperatively.

The preoperative conditions studied were demographic data, grade of surgical complexity (1–3), preoperative comorbidities, and some characteristically geriatric conditions (functional reserve, nutrition, cognitive status, polypharmacy, dependency, and frailty). The outcome measures were 30-day all-cause mortality (primary end point), morbidity, prolonged length of stay, and escalation of care in living conditions.

RESULTS:

Of 139 eligible patients, 127 completed follow-up. The 30-day mortality was 7.9%; 95% confidence interval (CI), 3.2–12.6. It had 3 predictors: malnutrition (odds ratio [OR], 15; 95% CI, 3–89), complexity 3 (OR, 9.1; CI, 2–52), and osteoporosis/osteoporotic fractures (OR, 14.7; CI, 2–126). Significant predictors for morbidity (40%) were ischemic heart disease (OR, 3.9; CI, 1–11) and complexity 3 (OR, 3.6; CI, 2–9), while a nonfrail phenotype (OR, 0.3; CI, 0.1–0.8) was found to be protective. Only 2 factors were found to be predictive of longer admissions, namely complexity 3 (OR, 4.4; CI, 2–10) and frailty (OR, 2.7; CI, 2–7). Finally, risk factors for escalation of care in living conditions were slow gait (a surrogate for frailty, OR, 2.5; CI, 1–6), complexity 3 (OR, 3.2; CI, 1–7), and hypertension (OR, 2.9; CI, 1–9).

CONCLUSIONS:

The eldest old is a distinct group with a considerable mortality rate and their own particular risk factors. Surgical complexity and certain geriatric variables (malnutrition and frailty), which are overlooked in American Society of Anesthesiologists and most other usual scores, are particularly relevant in this population. Inclusion of these factors along with appropriate comorbidities for risk stratification should guide better decision making for families and doctors alike and encourage preoperative optimization of patients.
An Appraisal of the Carlisle-Stouffer-Fisher Method for Assessing Study Data Integrity and Fraud
Authors: Mascha Edward J. , Vetter Thomas R. , Pittet Jean-Francois
Published: August 2017

Data fabrication and scientific misconduct have been recently uncovered in the anesthesia literature, partly via the work of John Carlisle. In a recent article inAnaesthesia, Carlisle analyzed 5087 randomized clinical trials from anesthesia and general medicine journals from 2000 to 2015. He concluded that in about 6% of studies, data comparing randomized groups on baseline variables, before the given intervention, were either too similar or dissimilar compared to that expected by usual sampling variability under the null hypothesis. Carlisle used the Stouffer-Fisher method of combiningPvalues in Table 1 (the conventional table reporting baseline patient characteristics) for each study, then calculated trialPvalues and assessed whether they followed a uniform distribution across studies. ExtremePvalues targeted studies as likely to contain data fabrication or errors. In this Statistical Grand Rounds article, we explain Carlisle’s methods, highlight perceived limitations of the proposed approach, and offer recommendations. Our main findings are (1) independence was assumed between variables in a study, which is often false and would lead to “false positive” findings; (2) an “unusual” result from a trial cannot easily be concluded to represent fraud; (3) utilized cutoff values for determining extremePvalues were arbitrary; (4) trials were analyzed as if simple randomization was used, introducing bias; (5) not allPvalues can be accurately generated from summary statistics in a Table 1, sometimes giving incorrect conclusions; (6) small numbers ofPvalues to assess outlier status within studies is not reliable; (7) utilized method to assess deviations from expected distributions may stack the deck; (8)Pvalues across trials assumed to be independent; (9)Pvalue variability not accounted for; and (10) more detailed methods needed to understand exactly what was done. It is not yet known to what extent these concerns affect the accuracy of Carlisle’s results. We recommend that Carlisle’s methods be improved before widespread use (applying them to every manuscript submitted for publication). Furthermore, lack of data integrity and fraud should ideally be assessed using multiple simultaneous statistical methods to yield more confident results. More sophisticated methods are needed for nonrandomized trials, randomized trial data reported beyond Table 1, and combating growing fraudster sophistication. We encourage all authors to more carefully scrutinize their own reporting. Finally, we believe that reporting of suspected data fraud and integrity issues should be done more discretely and directly by the involved journal to protect honest authors from the stigma of being associated with potential fraud.
BCAP is a centriolar satellite protein and inhibitor of ciliogenesis
Authors: de Saram Paul , Iqbal Anila , Murdoch Jennifer N. , Wilkinson Christopher J.
Published: August 2017

The centrosome and cilium are organelles with important roles in microtubule organisation, cell division, cell signalling, embryogenesis and tissue homeostasis. The two organelles are mutually exclusive. The centriole/basal body is found at the core of the centrosome (centriole) or at the base of the cilium (basal body) and to change which organelle is present in a cell requires modification to the centriole/basal body both in terms of composition and sub-cellular localisation. While many protein components required for centrosome and cilium biogenesis have been described, there are far fewer known inhibitors of ciliogenesis. Here, we show that a protein called BCAP and labelled in the sequence databases as ODF2-like (ODF2L) is a ciliation inhibitor. We show that it is a centriolar satellite protein. Furthermore, our data suggest that BCAP exists as two isoforms with subtly different roles in inhibition of ciliogenesis. Both are required to prevent ciliogenesis and one additionally controls cilium length after ciliogenesis has completed.
An ODE for an Overloaded X Model Involving a Stochastic Averaging Principle
Authors: Perry Ohad , Whitt Ward
Published: August 2017

We study an ordinary differential equation (ODE) arising as the many-server heavy-traffic fluid limit of a sequence of overloaded Markovian queueing models with two customer classes and two service pools. The system, known as the X model in the call-center literature, operates under the fixed-queue-ratio-with-thresholds (FQR-T) control, which we proposed in a recent paper as a way for one service system to help another in face of an unanticipated overload. Each pool serves only its own class until a threshold is exceeded; then one-way sharing is activated with all customer-server assignments then driving the two queues toward a fixed ratio. For large systems, that fixed ratio is achieved approximately. The ODE describes system performance during an overload. The control is driven by a queue-difference stochastic process, which operates in a faster time scale than the queueing processes themselves, thus achieving a time-dependent steady state instantaneously in the limit. As a result, for the ODE, the driving process is replaced by its long-run average behavior at each instant of time; i.e., the ODE involves a heavy-traffic averaging principle (AP).
Deterministic and Stochastic Primal-Dual Subgradient Algorithms for Uniformly Convex Minimization
Authors: Juditsky Anatoli , Nesterov Yuri
Published: August 2017

We discuss non-Euclidean deterministic and stochastic algorithms for optimization problems with strongly and uniformly convex objectives. We provide accuracy bounds for the performance of these algorithms and design methods which are adaptive with respect to the parameters of strong or uniform convexity of the objective: in the case when the total number of iterations N is fixed, their accuracy coincides, up to a logarithmic in N factor with the accuracy of optimal algorithms.
Diffusion Limits for Shortest Remaining Processing Time Queues
Authors: Gromoll H. Christian , Kruk Łukasz , Puha Amber L.
Published: August 2017

We present a heavy traffic analysis for a single server queue with renewal arrivals and generally distributed i.i.d. service times, in which the server employs the Shortest Remaining Processing Time (SRPT) policy. Under typical heavy traffic assumptions, we prove a diffusion limit theorem for a measure-valued state descriptor, from which we conclude a similar theorem for the queue length process. These results allow us to make some observations on the queue length optimality of SRPT. In particular, they provide the sharpest illustration of the well-known tension between queue length optimality and quality of service for this policy.
The Missing Piece Syndrome in Peer-to-Peer Communication
Authors: Hajek Bruce , Zhu Ji
Published: August 2017

Typical protocols for peer-to-peer file sharing over the Internet divide files to be shared into pieces. New peers strive to obtain a complete collection of pieces from other peers and from a seed. In this paper we investigate a problem that can occur if the seeding rate is not large enough. The problem is that, even if the statistics of the system are symmetric in the pieces, there can be symmetry breaking, with one piece becoming very rare. If peers depart after obtaining a complete collection, they can tend to leave before helping other peers receive the rare piece. Assuming that peers arrive with no pieces, there is a single seed, random peer contacts are made, random useful pieces are downloaded, and peers depart upon receiving the complete file, the system is stable if the seeding rate (in pieces per time unit) is greater than the arrival rate, and is unstable if the seeding rate is less than the arrival rate. The result persists for any piece selection policy that selects from among useful pieces, such as rarest first, and it persists with the use of network coding.
A Linear Response Bandit Problem
Authors: Goldenshluger Alexander , Zeevi Assaf
Published: August 2017

We consider a two–armed bandit problem which involves sequential sampling from two non-homogeneous populations. The response in each is determined by a random covariate vector and a vector of parameters whose values are not known a priori. The goal is to maximize cumulative expected reward. We study this problem in a minimax setting, and develop rate-optimal polices that combine myopic action based on least squares estimates with a suitable “forced sampling” strategy. It is shown that the regret grows logarithmically in the time horizon n and no policy can achieve a slower growth rate over all feasible problem instances. In this setting of linear response bandits, the identity of the sub-optimal action changes with the values of the covariate vector, and the optimal policy is subject to sampling from the inferior population at a rate that grows like [Formula: see text].
Brownian Inventory Models with Convex Holding Cost, Part 1: Average-Optimal Controls
Authors: Dai J. G. , Yao Dacheng
Published: August 2017

We consider an inventory system in which inventory level fluctuates as a Brownian motion in the absence of control. The inventory continuously accumulates cost at a rate that is a general convex function of the inventory level, which can be negative when there is a backlog. At any time, the inventory level can be adjusted by a positive or negative amount, which incurs a fixed cost and a proportional cost. The challenge is to find an adjustment policy that balances the holding cost and adjustment cost to minimize the long-run average cost. When both upward and downward fixed costs are positive, our problem is an impulse control problem. When both fixed costs are zero, our problem is a singular or instantaneous control problem. For the impulse control problem, we prove that a four-parameter control band policy is optimal among all feasible policies. For the singular control problem, we prove that a two-parameter control band policy is optimal.

We use a lower-bound approach, widely known as the “verification theorem”, to prove the optimality of a control band policy for both the impulse and singular control problems. Our major contribution is to prove the existence of a “smooth” solution to the free boundary problem under some mild assumptions on the holding cost function. The existence proof leads naturally to a numerical algorithm to compute the optimal control band parameters. We demonstrate that the lower-bound approach also works for a Brownian inventory model which prohibits an inventory backlog. A companion paper (“Brownian inventory models with convex holding cost, part 2: discount-optimal controls”, Stochastic Systems, Vol. 3, No. 2, pp. 500–573) explains how to adapt the lower-bound approach to study a Brownian inventory model under a discounted cost criterion.
Brownian Inventory Models with Convex Holding Cost, Part 2: Discount-Optimal Controls
Authors: Dai J. G. , Yao Dacheng
Published: August 2017

We consider an inventory system in which inventory level fluctuates as a Brownian motion in the absence of control. The inventory continuously accumulates cost at a rate that is a general convex function of the inventory level, which can be negative when there is a backlog. At any time, the inventory level can be adjusted by a positive or negative amount, which incurs a fixed positive cost and a proportional cost. The challenge is to find an adjustment policy that balances the inventory cost and adjustment cost to minimize the expected total discounted cost. We provide a tutorial on using a three-step lower-bound approach to solving the optimal control problem under a discounted cost criterion. In addition, we prove that a four-parameter control band policy is optimal among all feasible policies. A key step is the constructive proof of the existence of a unique solution to the free boundary problem. The proof leads naturally to an algorithm to compute the four parameters of the optimal control band policy.
Asymptotically Optimal Dynamic Pricing for Network Revenue Management
Authors: Atar Rami , Reiman Martin I.
Published: August 2017

A dynamic pricing problem that arises in a revenue management context is considered, involving several resources and several demand classes, each of which uses a particular subset of the resources. The arrival rates of demand are determined by prices, which can be dynamically controlled. When a demand arrives, it pays the posted price for its class and consumes a quantity of each resource commensurate with its class. The time horizon is finite: at time T the demands cease, and a terminal reward (possibly negative) is received that depends on the unsold capacity of each resource. The problem is to choose a dynamic pricing policy to maximize the expected total reward. When viewed in diffusion scale, the problem gives rise to a diffusion control problem whose solution is a Brownian bridge on the time interval [0, T]. We prove diffusion-scale asymptotic optimality of a dynamic pricing policy that mimics the behavior of the Brownian bridge.

The ‘target point’ of the Brownian bridge is obtained as the solution of a finite dimensional optimization problem whose structure depends on the terminal reward. We show that, in an airline revenue management problem with no-shows and overbooking, under a realistic assumption on the resource usage of the classes, this finite dimensional optimization problem reduces to a set of newsvendor problems, one for each resource.
Directed Random Graphs with given Degree Distributions
Authors: Chen Ningyuan , Olvera-Cravioto Mariana
Published: August 2017

Given two distributions F and G on the nonnegative integers we propose an algorithm to construct in- and out-degree sequences from samples of i.i.d. observations from F and G, respectively, that with high probability will be graphical, that is, from which a simple directed graph can be drawn. We then analyze a directed version of the configuration model and show that, provided that F and G have finite variance, the probability of obtaining a simple graph is bounded away from zero as the number of nodes grows. We show that conditional on the resulting graph being simple, the in- and out-degree distributions are (approximately) F and G for large size graphs. Moreover, when the degree distributions have only finite mean we show that the elimination of self-loops and multiple edges does not significantly change the degree distributions in the resulting simple graph.
Mean Square Convergence Rates for Maximum Quasi-Likelihood Estimators
Authors: den Boer Arnoud V. , Zwart Bert
Published: August 2017

In this note we study the behavior of maximum quasilikelihood estimators (MQLEs) for a class of statistical models, in which only knowledge about the first two moments of the response variable is assumed. This class includes, but is not restricted to, generalized linear models with general link function. Our main results are related to guarantees on existence, strong consistency and mean square convergence rates of MQLEs. The rates are obtained from first principles and are stronger than known a.s. rates. Our results find important application in sequential decision problems with parametric uncertainty arising in dynamic pricing.
On the Dynamic Control of Matching Queues
Authors: Gurvich Itai , Ward Amy
Published: August 2017

We consider the optimal control of matching queues with random arrivals. In this model, items arrive to dedicated queues, and wait to be matched with items from other (possibly multiple) queues. A match type corresponds to the set of item classes required for a match. Once a decision has been made to perform a match, the matching itself is instantaneous and the matched items depart from the system. We consider the problem of minimizing finite-horizon cumulative holding costs. The controller must decide which matchings to execute given multiple options. In principle, the controller may choose to wait until some “inventory” of items builds up to facilitate more profitable matches in the future.

We introduce a multi-dimensional imbalance process, that at each time t, is given by a linear function of the cumulative arrivals to each of the item classes. A non-zero value of the imbalance at time t means that no control could have matched all the items that arrived by time t. A lower bound based on the imbalance process can be specified, at each time point, by a solution to an optimization problem with linear constraints. While not achievable in general, this lower bound can be asymptotically approached under a dedicated item condition (an analogue of the local traffic condition in bandwidth sharing networks). We devise a myopic discrete-review matching control that asymptotically–as the arrival rates become large–achieves the imbalance-based lower bound.
An Asymptotic Optimality Result for the Multiclass Queue with Finite Buffers in Heavy Traffic
Authors: Atar Rami , Shifrin Mark
Published: August 2017

For a multiclass G/G/1 queue with finite buffers, admission and scheduling control, and holding and rejection costs, we construct a policy that is asymptotically optimal in the heavy traffic limit. The policy is specified in terms of a single parameter which constitutes the free boundary point from the Harrison-Taksar free boundary problem, but otherwise depends explicitly on the problem data. The cμ priority rule is also used by the policy, but in a way that is novel, and, in particular, different than that used in problems with infinite buffers. We also address an analogous problem where buffer constraints are replaced by throughput time constraints.
Moderate Deviations for Recursive Stochastic Algorithms
Authors: Dupuis Paul , Johnson Dane
Published: August 2017

We prove a moderate deviation principle for the continuous time interpolation of discrete time recursive stochastic processes. The methods of proof are somewhat different from the corresponding large deviation result, and in particular the proof of the upper bound is more complicated.
Tightness of Stationary Distributions of a Flexible-Server System in the Halfin-Whitt Asymptotic Regime
Authors: Stolyar Alexander L.
Published: August 2017

A large-scale flexible service system with two large server pools and two types of customers is considered. Servers in pool 1 can only serve type 1 customers, while server in pool 2 are flexible – they can serve both types 1 and 2. (This is a so-called “N-system.”) The customer arrival processes are Poisson and customer service requirements are independent exponentially distributed. The service rate of a customer depends both on its type and the pool where it is served. A priority service discipline, where type 2 has priority in pool 2, and type 1 prefers pool 1, is considered. We consider the Halfin-Whitt asymptotic regime, where the arrival rate of customers and the number of servers in each pool increase to infinity in proportion to a scaling parameter n, while the overall system capacity exceeds its load by [Formula: see text].

For this system we prove tightness of diffusion-scaled stationary distributions. Our approach relies on a single common Lyapunov function G(n)(x), depending on parameter n and defined on the entire state space as a functional of the drift-based fluid limits (DFL). Specifically, [Formula: see text], where y(n)(·) is the DFL starting at x, and g(·) is a “distance” to the origin. (g(·) is same for all n). The key part of the analysis is the study of the (first and second) derivatives of the DFLs and function G(n)(x). The approach, as well as many parts of the analysis, are quite generic and may be of independent interest.
Control of Parallel Non-observable Queues: Asymptotic Equivalence and Optimality of Periodic Policies
Authors: Anselmi Jonatha , Gaujal Bruno , Nesti Tommaso
Published: August 2017

We consider a queueing system composed of a dispatcher that routes jobs to a set of non-observable queues working in parallel. In this setting, the fundamental problem is which policy should the dispatcher implement to minimize the stationary mean waiting time of the incoming jobs. We present a structural property that holds in the classic scaling of the system where the network demand (arrival rate of jobs) grows proportionally with the number of queues. Assuming that each queue of type r is replicated k times, we consider a set of policies that are periodic with period [Formula: see text] and such that exactly pr jobs are sent in a period to each queue of type r. When k → ∞, our main result shows that all the policies in this set are equivalent, in the sense that they yield the same mean stationary waiting time, and optimal, in the sense that no other policy having the same aggregate arrival rate to all queues of a given type can do better in minimizing the stationary mean waiting time. This property holds in a strong probabilistic sense. Furthermore, the limiting mean waiting time achieved by our policies is a convex function of the arrival rate in each queue, which facilitates the development of a further optimization aimed at solving the fundamental problem above for large systems.
Heavy-traffic Limit for the Initial Content Process
Authors: Aras A. Korhan , Liu Yunan , Whitt Ward
Published: August 2017

To understand the performance of a queueing system, it can be useful to focus on the evolution of the content that is initially in service at some time. That necessarily will be the case in service systems that provide service during normal working hours each day, with the system shutting down at some time, except that all customers already in service at the termination time are allowed to complete their service. Also, for infinite-server queues, it is often fruitful to partition the content into the initial content and the new input, because these can be analyzed separately. With i.i.d service times having a non-exponential distribution, the state of the initial content can be described by specifying the elapsed service times of the remaining initial customers. That initial content process is then a Markov process. This paper establishes a many-server heavy-traffic (MSHT) functional central limit theorem (FCLT) for the initial content process in the space 𝔻𝔻, assuming a FCLT for the initial age process, with the number of customers initially in service growing in the limit. The proof applies a symmetrization lemma from the literature on empirical processes to address a technical challenge: For each time, including time 0, the conditional remaining service times, given the ages, are mutually independent but in general not identically distributed.