bluuebunny/crossref_metadata_2025 huggingface dataset:
CI Camelopardalis: The first sgB[e]-high mass X-ray binary twenty years on: A supernova imposter in our own Galaxy?
Authors: Bartlett E. S. , Clark J. S. , Negueruela I.
Published: December 2018

Context. The Galactic supergiant B[e] star CI Camelopardalis (CI Cam) was the first sgB[e] star detected during an X-ray outburst. The star brightened to ∼2 Crab in the X-ray regime (∼5 × 10−8 ergs cm−2 s−1 in the 2–25 keV range) within hours before decaying to a quiescent level in less than two weeks, clearly indicative of binarity. Since the outburst of CI Cam, several sgB[e] stars have been identified as X-ray overluminous for a single star (i.e. LX >  10−7 Lbol). This small population has recently expanded to include two ultra luminous X-ray sources (ULX), Holmberg II X-1 and NGC 300 ULX-1/supernova imposter SN2010da.

Aims. Since the discovery of X-ray emission from CI Cam, there have been many developments in the field of massive binary evolution. In light of the recent inclusion of two ULXs in the population of X-ray bright sgB[e] stars, we revisit CI Cam to investigate its behaviour over several timescales and shed further light on the nature of the compact object in the system, its X-ray outburst in 1998 and the binary system parameters.

Methods. We analysed archival XMM-Newton EPIC-pn spectra and light curves along with new data from Swift and NuSTAR. We also present high-resolution (R ∼ 85 000) Mercator/HERMES optical spectra, including a spectrum taken 1.02 days after our NuSTAR observation.

Results. Despite being in quiescence, CI Cam is highly X-ray variable on timescales of days, both in terms of total integrated flux and spectral shape. We interpret these variations by invoking the presence of an accreting compact companion immersed in a dense, highly structured, aspherical circumstellar envelope. The differences in the accretion flux and circumstellar extinction represent either changes in this environment, triggered by variable mass loss from the star, or the local conditions to the accretor due to its orbital motion. We find no evidence for pulsations in the X-ray light curve.

Conclusions. CI Cam has many similarities with SN2010da across mid-IR, optical and X-ray wavelengths suggesting that, subject to distance determination for CI Cam, if CI Cam was located in an external galaxy its 1998 outburst would have led to a classification as a supernova imposter.
Transform your human resources processes to improve your patient’s care, quality, and results
Authors: Boukhobza A. , Etchebarne T.
Published: December 2018

The purpose of this article is to identify what are the human resources processes to be implemented in orthodontic practices to both improve the management of patients, but also the profitability of the structure in terms of both organization and financial.

The work on the cohesion of the teams will create a collective commitment which depends on the one hand on the quality of the recruitment of the employees, and then on the motivation levers set up within the teams and maintained over time. In the teams the intergenerational collaboration must be managed and optimized.

On the other hand, the orthodontist leader must have a clear strategy and clear objectives to be able to communicate effectively. He must also know the communication tools according to the circumstances to convey the messages he needs.
Cutoff Points, Sensitivities, and Specificities of Intraoperative Motor-Evoked Potential Monitoring Determined Using Receiver Operating Characteristic Analysis
Authors: Akimoto Jiro , Hashimoto Ryo , Takanashi Junko , Oka Hidehiro , Tanaka Satoshi
Published: December 2018

Background Although intraoperative motor-evoked potential (MEP) monitoring is widely performed during neurosurgical operations, evaluating its results is controversial.

Study Aims The cutoff point of MEP monitoring should be determined not only to predict but also to prevent postoperative neurologic deficits.

Material and Methods MEP monitoring was performed during 484 neurosurgical operations for patients without definitive preoperative motor palsy including 325 spinal operations, 102 cerebral aneurysmal operations, and 57 brain tumor operations, all monitored by transcranial stimulation, and 34 brain tumor operations monitored under direct cortical stimulation. To exclude the effects of muscle relaxants on MEP, the compound muscle action potential (CMAP), measured immediately after transcranial stimulation or direct cortical stimulation at supramaximal stimulation of the peripheral nerve, was used for normalization. The cutoff points, sensitivity, and specificity of MEP recorded during neurosurgery were examined by receiver operating characteristic (ROC) analyses and categorized according to the type of operation and stimulation.

Results In spinal operations under transcranial stimulation, amplitude reduction of 77.9% and 80.6% as cutoff points for motor palsy with and without CMAP normalization, respectively, provided a sensitivity of 100% and specificity of 96.8% and 96.5%. In aneurysmal operations under transcranial stimulation, cutoff points of 70.7% and 69.6% offered specificities of 95.2% and 95.7% with and without CMAP normalization, respectively. The sensitivities for both were 100%. In brain tumor operations under direct stimulation, cutoff points were 83.5% and 86.3% with or without CMAP normalization, respectively, and the sensitivity and specificity for both were 100%.

Conclusion An amplitude decrease of 80% in brain tumor operations, 75% in spinal operations, and 70% in aneurysmal operations should be used as the cutoff points.
Asymptotic bounds for spherical codes
Authors: Manin Yu. I. , Marcolli M.
Published: December 2018

The set of all error-correcting codes

over a fixed finite alphabet

of cardinality

determines the set of code points in the unit square

with coordinates

:= (relative transmission rate, relative minimal distance). The central problem of the theory of such codes consists in maximising simultaneously the transmission rate of the code and the relative minimum Hamming distance between two different code words. The classical approach to this problem explored in vast literature consists in inventing explicit constructions of “good codes” and comparing new classes of codes with earlier ones.

A less classical approach studies the geometry of the whole set of code points

(with

fixed), at first independently of its computability properties, and only afterwards turning to problems of computability, analogies with statistical physics, and so on.

The main purpose of this article consists in extending this latter strategy to the domain of spherical codes.
Division by

on odd-degree hyperelliptic curves and their Jacobians
Authors: Zarhin Yu. G.
Published: December 2018

Let

be an algebraically closed field of characteristic different from

,

a positive integer,

a polynomial of degree

with coefficients in

and without multiple roots,

the corresponding hyperelliptic curve of genus

over

, and

its Jacobian. We identify

with the image of its canonical embedding in

(the infinite point of

goes to the identity element of

). It is well known that for every

there are exactly

elements

such that

. Stoll constructed an algorithm that provides the Mumford representations of all such

in terms of the Mumford representation of

. The aim of this paper is to give explicit formulae for the Mumford representations of all such

in terms of the coordinates

, where

is given by a point

. We also prove that if

, then

does not contain torsion points of orders between

and

.
Birationally rigid complete intersections of high codimension
Authors: Evans D. , Pukhlikov A. V.
Published: December 2018

We prove that a Fano complete intersection of codimension

and index

in the complex projective space

for

and

with at most multi-quadratic singularities is birationally superrigid. The codimension of the complement of the set of birationally superrigid complete intersections in the natural moduli space is shown to be at least

. The proof is based on the technique of hypertangent divisors combined with the recently discovered

-inequality for complete intersection singularities.
The discrete spectrum of the Laplace operator on the fundamental domain of the modular group and the Chebyshev psi-function
Authors: Popov D. A.
Published: December 2018

An explicit formula is obtained expressing the Chebyshev psi- function in terms of the discrete spectrum of the Laplace operator on the fundamental domain of the modular group.
Conformally invariant inequalities in domains in Euclidean space
Authors: Avkhadiev F. G.
Published: December 2018

We study conformally invariant integral inequalities for real-valued functions defined on domains

in

-dimensional Euclidean space. The domains considered are of hyperbolic type, that is, they admit a hyperbolic radius

satisfying the Liouville non-linear differential equation and vanishing on the boundary of the domain. We prove several inequalities which hold for all smooth compactly supported functions

defined on a given domain of hyperbolic type. Here are two of them:

where

,

and

. We also study the relations between Euclidean and hyperbolic characteristics of domains.
Nice triples and moving lemmas for motivic spaces
Authors: Panin I. A.
Published: December 2018

This paper contains geometric tools developed to solve the finite-field case of the Grothendieck–Serre conjecture in [1]. It turns out that the same machinery can be applied to solve some cohomological questions.

In particular, for any presheaf of

-spectra

on the category of

-smooth schemes, all its Nisnevich sheaves of

-stable homotopy groups are strictly homotopy invariant. This shows that

is

-local if and only if all its Nisnevich sheaves of ordinary stable homotopy groups are strictly homotopy invariant. The latter result was obtained by Morel [2] in the case when the field

is infinite.

However, when

is finite, Morel’s proof does not work since it uses Gabber’s presentation lemma and there is no published proof of that lemma. We do not use Gabber’s presentation lemma. Instead, we develop the machinery of nice triples invented in [3]. This machinery is inspired by Voevodsky’s technique of standard triples [4].
On accumulation points of volumes of log surfaces
Authors: Alexeev V. A. , Liu W.
Published: December 2018

Let

be a set satisfying the descending chain condition. We show that every accumulation point of volumes of log canonical surfaces

with coefficients in

can be realized as the volume of a log canonical surface with big and nef

and with coefficients in

in such a way that at least one coefficient lies in

. As a corollary, if

, then all accumulation points of volumes are rational numbers. This proves a conjecture of Blache. For the set of standard coefficients

we prove that the minimal accumulation point is between

and

.
Crystallography characteristics of tetragonal nano-zirconia films under various oxygen partial pressure
Authors: Eftekhari Leila , Raoufi Davood
Published: December 2018

Structural features and surface morphology of ZrO [Formula: see text] thin films electron beam evaporation-deposited under various oxygen partial pressure were studied. It was indicated tetragonal phase for all samples by XRD pattern. The highest crystallite size calculated via Scherrer equation is observed at the oxygen partial pressure of [Formula: see text]  mbar; that was in good agreement with the high-resolution surface images obtained by FE-SEM. The photoluminescence spectrum of t-zirconia films exhibits an intense peak at 351 nm, this emission decrease in intensity by elevation of oxygen partial pressures. Surface roughness profile and scaling analyses were made by surface measurements of atomic force microscopy with using the height-height correlation function. The roughness has the maximum value at the highest oxygen partial pressure. It has been found that with the increase of oxygen partial pressures, lateral correlation length of samples increased, and fractal dimension changed within the range of 2.20–2.26.
Multiview: a software package for multiview pattern recognition methods
Authors: Kanaan-Izquierdo Samir , Ziyatdinov Andrey , Burgueño Maria Araceli , Perera-Lluna Alexandre
Published: December 2018

Multiview datasets are the norm in bioinformatics, often under the label multi-omics. Multiview data are gathered from several experiments, measurements or feature sets available for the same subjects. Recent studies in pattern recognition have shown the advantage of using multiview methods of clustering and dimensionality reduction; however, none of these methods are readily available to the extent of our knowledge. Multiview extensions of four well-known pattern recognition methods are proposed here. Three multiview dimensionality reduction methods: multiview t-distributed stochastic neighbour embedding, multiview multidimensional scaling and multiview minimum curvilinearity embedding, as well as a multiview spectral clustering method. Often they produce better results than their single-view counterparts, tested here on four multiview datasets.

Availability and implementation

R package at the B2SLab site: http://b2slab.upc.edu/software-and-tutorials/ and Python package: https://pypi.python.org/pypi/multiview.

Supplementary information

Supplementary data are available at Bioinformatics online.
GfaViz: flexible and interactive visualization of GFA sequence graphs
Authors: Gonnella Giorgio , Niehus Niklas , Kurtz Stefan
Published: December 2018

The graphical fragment assembly (GFA) formats are emerging standard formats for the representation of sequence graphs. Although GFA 1 was primarily targeting assembly graphs, the newer GFA 2 format introduces several features, which makes it suitable for representing other kinds of information, such as scaffolding graphs, variation graphs, alignment graphs and colored metagenomic graphs. Here, we present GfaViz, an interactive graphical tool for the visualization of sequence graphs in GFA format. The software supports all new features of GFA 2 and introduces conventions for their visualization. The user can choose between two different layouts and multiple styles for representing single elements or groups. All customizations can be stored in custom tags of the GFA format itself, without requiring external configuration files. Stylesheets are supported for storing standard configuration options for groups of files. The visualizations can be exported to raster and vector graphics formats. A command line interface allows for batch generation of images.

Availability and implementation

GfaViz is available at https://github.com/ggonnella/gfaviz

Supplementary information

Supplementary data are available at Bioinformatics online.
Linking sequence patterns and functionality of alpha-helical antimicrobial peptides
Authors: Eliseev Igor E , Terterov Ivan N , Yudenko Anna N , Shamova Olga V
Published: December 2018

Motivation

The rational design of antimicrobial peptides (AMPs) with increased therapeutic potential requires deep understanding of the determinants of their activities. Inspired by the computational linguistic approach, we hypothesized that sequence patterns may encode the functional features of AMPs.

Results

We found that α-helical and β-sheet peptides have non-intersecting pattern sets and therefore constructed new sequence templates using only helical patterns. Designed peptides adopted an α-helical conformation upon binding to lipids, confirming that the method captures structural and biophysical properties. In the antimicrobial assay, 5 of 7 designed peptides exhibited activity against Gram(+) and Gram(–) bacteria, with most potent candidate comparable to best natural peptides. We thus conclude that sequence patterns comprise the structural and functional features of α-helical AMPs and guide their efficient design.

Supplementary information

Supplementary data are available at Bioinformatics online.
An empirical analysis of Minsky regimes in the US economy
Authors: Davis Leila E , de Souza Joao Paulo A , Hernandez Gonzalo
Published: December 2018

In this paper, we analyse Minskian dynamics in the US economy via an empirical application of Minsky’s financing regime classifications to a panel of nonfinancial corporations. First, we map Minsky’s definitions of hedge, speculative and Ponzi finance onto firm-level data to describe the evolution of Minskian regimes. We highlight striking growth in the share of Ponzi firms in the post-1970 US, concentrated among small corporations. This secular growth in the incidence of Ponzi firms is consistent with the possibility of a long wave of increasingly fragile finance in the US economy. Second, we explore the possibility of short-run Minskian dynamics at a business cycle frequency. Using linear probability models relating firms’ probability of being Ponzi to the aggregate output gap, which captures short-term macroeconomic fluctuations exogenous to individual firms, we find that the relationship between aggregate downturns and the probability of being Ponzi is statistically significant, but very small (almost zero). This result is corroborated by quantile regressions using a continuous measure of financial fragility, the interest coverage ratio, which identify almost zero effects of short-term fluctuations on financial fragility across the interest coverage distribution. Together, these results speak to an important question in the theoretical literature on financial fragility regarding the duration of Minskian cycles, and lend support, in particular, to the contention that Minskian dynamics may take the form of long waves, but do not operate at business cycle frequencies.
Consumer perceptions of health IT utilization and benefits
Authors: Feldman Sue S , Bhavsar Grishma P , Schooley Benjamin L
Published: December 2018

Objectives

The objective of this article is to examine consumer perceptions of health information technology (health IT) utilization and benefits through an integrated conceptual framework.

Materials and Methods

This article employs an integrated conceptual framework to examine consumer perceptions of health IT. A consumer survey yielded 1125 completed responses. A factor-based scale was developed for each sub-construct. Bivariate analysis using χ2 tests was performed to determine differences in the percentage of respondents who agreed with each sub-construct based on whether their physician used an electronic health record (EHR) system. Multivariable logistic regression that controlled for demographic characteristics of respondents was performed to determine adjusted odds of agreeing with selected opinions of health information exchange (HIE).

Results

Results indicate that respondents whose physicians used an EHR system were significantly more likely to agree that there was a perceived benefit with HIE and to care provided; that the patient should have control over the record; that they trust the physician and security of the medical information; that they understand the need for HIE, and that HIE must be easy to use.

Discussion

The results suggest that consumers who have experienced the use of one technology in the healthcare setting can recognize the potential benefit of another technology. Race/ethnicity, gender, and education played some role in respondents’ views of EHRs and HIE, more specifically, non-Hispanic African American participants indicated lower levels of trust in HIE when compared with non-Hispanic Whites.

Conclusion

This cross-sectional survey indicated that physician use of EHRs significantly increases the odds of consumers’ seeing perceived benefits of HIE and understanding the need for HIE.
A novel case of late left ventricular outflow tract obstruction post mitral valve surgery
Authors: Jones Andrew , Livesey Steven
Published: December 2018

Left ventricular outflow tract (LVOT) obstruction (LVOTO) is a rare but recognized complication of mitral valve surgery. Concomitant factors can cause significant clinical deterioration which requires urgent intervention. We present the case of a female patient who underwent closed valvotomy at age 20 for mitral stenosis secondary to rheumatic heart disease. Seventeen years later, a re-stenosed valve prompted mitral valve replacement (MVR) with a Carbomedics mechanical prosthesis. 8 years later, she re-presented with increasing dyspnoea. On echocardiogram a frond-like structure was visible in the LVOT, the valve housing was protruding into the LVOT and she had marked septal hypertrophy. The LVOT gradient was 72 mmHg. This is a novel case of mechanical MVR associated LVOTO due to at least three discrete factors. This case demonstrates how multiple factors can amalgamate to result in significant clinical deterioration. Over an 8-year period, all three distinct factors contributed to the development of severe LVOTO.
Traction does not decrease failure of reduction and femoral head avascular necrosis in patients aged 6–24 months with developmental dysplasia of the hip treated by closed reduction: a review of 385 patients and meta-analysis
Authors: Li Yi-Qiang , Li Ming , Guo Yue-Ming , Shen Xian-Tao , Mei Hai-Bo , Chen Shun-You , Shao Jing-Fan , Tang Sheng-Ping , Canavese Federico , Xu Hong-Wen
Published: December 2018

This study aimed to investigate the effects of preliminary traction on the rate of failure of reduction and the incidence of femoral head avascular necrosis (AVN) in patients with late-detected developmental dysplasia of the hip treated by closed reduction. A total of 385 patients (440 hips) treated by closed reduction satisfied the inclusion criteria. Patients were divided in two groups according to treatment modality: a traction group (276 patients) and a no-traction group (109 patients). Tönnis grade, rate of failure reduction, AVN rate, acetabular index, center-edge angle of Wiberg, and Severin’s radiographic grade were assessed on plain radiographs, and the results were compared between the two groups of patients. In addition, a meta-analysis was performed based on the existing comparative studies to further evaluate the effect of traction on the incidence of AVN. Tönnis grade in the traction group was significantly higher than in the no-traction group (P = 0.021). The overall rate of failure reduction was 8.2%; no significant difference was found between the traction (9.2%) and no-traction groups (5.6%) (P = 0.203). The rates of failure reduction were similar in all Tönnis grades, regardless of treatment modality (P > 0.05). The rate of AVN in the traction group (14%) was similar to that of the no-traction group (14.5%; P = 0.881). Moreover, the rates of AVN were similar in all Tönnis grades, regardless of treatment modality (P > 0.05). The meta-analysis did not identify any significant difference in the AVN rate whether preliminary traction was used or not (odds ratio = 0.76, P = 0.32). At the last follow-up visit, the two groups of patients had comparable acetabular indices, center-edge angles, and Severin’s radiographic grades (P > 0.05). In conclusion, preliminary traction does not decrease the failure of reduction and the incidence of AVN in developmental dysplasia of the hip treated by closed reduction between 6 and 24 months of age.
Menopausal hormone therapy trends before versus after 2002: impact of the Women's Health Initiative Study Results
Authors: Crawford Sybil L. , Crandall Carolyn J. , Derby Carol A. , Khoudary Samar R. El , Waetjen L. Elaine , Fischer Mary , Joffe Hadine
Published: December 2018

Objective:

To better understand how to educate patients and providers about study findings relevant to treatment guidelines, we assessed pre- versus post-Women's Health Initiative (WHI) differences in menopausal hormone therapy (MHT) initiation and continuation and their correlates, and in women's reasons for initiation and discontinuation.

Methods:

We analyzed survey data from up to 14 approximately annual visits over 17 years (1996-2013) from 3,018 participants in the Study of Women's Health Across the Nation, a prospective cohort study. We used logistic regression to compare pre- versus post-WHI associations of covariates with MHT initiation and continuation, and to compare pre- versus post-WHI reasons for initiation and continuation.

Results:

MHT initiation dropped from 8.6% pre-WHI to 2.8% post-WHI (P < 0.0001), and the corresponding decrease in MHT continuation was 84.0% to 62.0% (P < 0.0001). Decreases in MHT initiation and continuation occurred across a range of participant subgroups, consistent with wide dissemination of post-WHI recommendations. However, contrary to current guidelines, we found large declines in MHT use in subgroups for whom MHT is often recommended, that is, younger women and those with more vasomotor symptoms. Post-WHI, women's reasons for MHT initiation and discontinuation reflected concerns highlighted by WHI results. The largest declines in initiation reasons were for reducing risks of osteoporosis and heart disease, whereas the largest increases in discontinuation reasons were for media reports and provider advice.

Conclusions:

Immediate post-WHI recommendations for MHT use were widely adopted. MHT risks documented in older women, however, may have led younger symptomatic women to forgo MHT for symptom relief.
Medical Radiation Exposure in the United States: 2006–2016 Trends
Authors: Mettler Fred A.
Published: December 2018

The use of radiation in medicine and the associated population dose grew very rapidly from 1980–2006 predominantly as a result of computed tomography and nuclear medicine. Over the last decade there have been significant changes in image detectors and processing with almost complete elimination of film use. Economic and reimbursement issues have also had a significant effect on usage. After about 2010, the volume of computed tomography and interventional techniques has been fairly level, plain radiography has declined slightly, and noninterventional fluoroscopy has declined dramatically. Nuclear medicine procedures have also declined significantly. Cone-beam computed tomography has expanded particularly in dental radiography. The use of several complex types of image-guided radiotherapy has increased significantly. National Council on Radiation Protection and Measurements’ Scientific Committee 4-9 is currently conducting a full assessment for 2016 of collective and per caput effective dose. The report is expected to be completed in 2019, and preliminary work suggests a decrease in collective and per caput effective dose from that previously estimated for 2006.
Communicating Radiation Risk: The Power of Planned, Persuasive Messaging
Authors: Wieder Jessica S.
Published: December 2018

Every day, health physicists and physicians are expected to communicate effectively with concerned people, but rarely (if ever) are they given training on how to effectively communicate. In an age of social media, this paper presents the relevance of teachings from an ancient Greek philosopher. Aristotle’s Rhetoric is still considered one of the most influential works on persuasive messaging. He puts the onus of effective communications on the people with the “true” and “just” information to communicate that information clearly to the audience. By communicating with intention—using the persuasive appeals of ethos, pathos, logos, and storytelling—radiation professionals can speak to their expertise in radiation science, while adapting their instructions, presentations, and communication styles to meet the needs of each type of audience: from scientists to concerned citizens, from doctors to first responders, and beyond.
Radiopharmaceutical Therapy
Authors: Sgouros George
Published: December 2018

Radiopharmaceutical therapy involves the use of radionuclides that are either conjugated to tumor-targeting agents (e.g., nanoscale constructs, antibodies, peptides, and small molecules) or that concentrate in tumors through natural physiological mechanisms that occur predominantly in neoplastic cells. In the latter category, radioiodine therapy of thyroid cancer is the prototypical and most widely implemented radiopharmaceutical therapy. In the category of radionuclide-ligand conjugates, antibody and peptide conjugates have been studied extensively. The efficacy of radiopharmaceutical therapy relies on the ability to deliver cytotoxic radiation to tumor cells without causing prohibitive normal tissue toxicity. After some 30 y of preclinical and clinical research, a number of recent developments suggest that radiopharmaceutical therapy is poised to emerge as an important and widely recognized therapeutic modality. These developments include the substantial investment in antibodies by the pharmaceutical industry and the compelling rationale to build upon this already existing and widely tested platform. In addition, the growing recognition that the signaling pathways responsible for tumor cell survival and proliferation are less easily and durably inhibited than originally envisioned has also provided a rationale for identifying agents that are cytotoxic rather than inhibitory. A number of radiopharmaceutical agents are currently undergoing clinical trial investigation; these include beta-particle emitters, such as 177Lu, that are being used to label antisomatostatin receptor peptides for neuroendocrine cancers and also prostate-specific membrane antigen targeting small molecules for prostate cancer. Alpha-particle-emitting radionuclides have also been studied for radiopharmaceutical therapy; these include 211At for glioblastoma, 225Ac for leukemias and prostate cancer, 212Pb for breast cancer, and 223Ra for prostate cancer. The alpha emitters have tended to show particular promise, and there is substantial interest in further developing these agents for therapy of cancers that are particularly difficult to treat.
Uses of Effective Dose: The Good, the Bad, and the Future
Authors: Bushberg Jerrold T.
Published: December 2018

Effective dose (E) is a risk-adjusted dosimetric quantity developed by the International Commission on Radiological Protection. It is a key metric for practical management of the risk of stochastic health effects in a comprehensive radiation protection program. The International Commission on Radiological Protection and others have emphasized repeatedly that E is not intended to represent an actual radiation dose and should not be used as a risk-related metric for a specific person or population. The cancer risk uncertainties in the low-dose range and the underlying approximations, simplifications, and sex- and age-averaging used in generating E make it unsuitable for this purpose. However, in practice, medical imaging professionals and authors of peer-reviewed medical publications frequently and incorrectly use E as a surrogate for whole-body dose in order to calculate cancer risk estimates for specific patients or patient populations. This frequent misuse has popularized E for uses for which it was neither designed nor intended. Alternatives to E have been proposed that attempt to account for known age and sex differences in radiation sensitivity. E has also been proposed as a general indicator for communicating radiation risk to patients, if its limitations are kept in mind. Forthcoming guidance from the International Commission on Radiological Protection will likely clarify if, when, and how some form of E may be used as a rough indicator of the risk of a stochastic effect, possibly with some modifications for the substantial variations in risk known to exist with respect to age, sex, and population group.
Recent Epidemiologic Studies and the Linear No-Threshold Model For Radiation Protection—Considerations Regarding NCRP Commentary 27
Authors: Shore Roy E. , Beck Harold L. , Boice John D. , Caffrey Emily A. , Davis Scott , Grogan Helen A. , Mettler Fred A. , Preston R. Julian , Till John E. , Wakeford Richard , Walsh Linda , Dauer Lawrence T.
Published: December 2018

National Council on Radiation Protection and Measurements Commentary 27 examines recent epidemiologic data primarily from low-dose or low dose-rate studies of low linear-energy-transfer radiation and cancer to assess whether they support the linear no-threshold model as used in radiation protection. The commentary provides a critical review of low-dose or low dose-rate studies, most published within the last 10 y, that are applicable to current occupational, environmental, and medical radiation exposures. The strengths and weaknesses of the epidemiologic methods, dosimetry assessments, and statistical modeling of 29 epidemiologic studies of total solid cancer, leukemia, breast cancer, and thyroid cancer, as well as heritable effects and a few nonmalignant conditions, were evaluated. An appraisal of the degree to which the low-dose or low dose-rate studies supported a linear no-threshold model for radiation protection or on the contrary, demonstrated sufficient evidence that the linear no-threshold model is inappropriate for the purposes of radiation protection was also included. The review found that many, though not all, studies of solid cancer supported the continued use of the linear no-threshold model in radiation protection. Evaluations of the principal studies of leukemia and low-dose or low dose-rate radiation exposure also lent support for the linear no-threshold model as used in protection. Ischemic heart disease, a major type of cardiovascular disease, was examined briefly, but the results of recent studies were considered too weak or inconsistent to allow firm conclusions regarding support of the linear no-threshold model. It is acknowledged that the possible risks from very low doses of low linear-energy-transfer radiation are small and uncertain and that it may never be possible to prove or disprove the validity of the linear no-threshold assumption by epidemiologic means. Nonetheless, the preponderance of recent epidemiologic data on solid cancer is supportive of the continued use of the linear no-threshold model for the purposes of radiation protection. This conclusion is in accord with judgments by other national and international scientific committees, based on somewhat older data. Currently, no alternative dose-response relationship appears more pragmatic or prudent for radiation protection purposes than the linear no-threshold model.
Medical Physics 3.0: Ensuring Quality and Safety in Medical Imaging
Authors: Samei Ehsan
Published: December 2018

Medical imaging often involves radiation and thus radiation protection. Radiation protection in medicine is only one component of the broader calling of health care professionals: fostering human health. As such, radiation risk needs to be put into the context of the larger mandate of improved outcomes in health care. Medical physicists, according to the new vision of Medical Physics 3.0, make a significant contribution to this mandate as they engage proactively and meaningfully in patient care. Facing the new realities of value-based, personalized, and evidence-based practice, Medical Physics 3.0 is an initiative to make physics inform every patient’s care by fostering new skills and expanding horizons for the medical physics profession. It provides a framework by which medical physicists can maintain and improve their integral roles in, and contributions to, health care, its innovation, and its precision. One way that Medical Physics 3.0 will manifest itself in medical imaging practice is by engaging physicists to ensure the precise and optimized use of radiation. Optimization takes place through knowing the defining attributes of the technology in use, the specifics of the patient’s situation, and the goals of the imaging and/or intervention. The safety as well as the quality of the procedure is ascertained quantitatively and optimized prospectively, ensuring a proper balance between quality and safety to offer maximum potential benefit to the patient. The results of procedures across the health care operation are then retrospectively analyzed to ensure that each procedure has, in actuality, delivered the targeted quality and safety objectives. Characterizing quality and safety in quantitative terms, objectively optimizing them in the practice of personalized care, and analyzing the results from clinical operations all require the unique combination of precision and innovation that physicists bring to the development and practice of medicine.
Projection X-ray Imaging: Radiography, Mammography, Fluoroscopy
Authors: Seibert James Anthony
Published: December 2018

Recent advances in digital detector technology for medical radiography and fluoroscopy have resulted in improved workflow efficiency, operational flexibility, image quality, and diagnostic accuracy. This is attributed to the implementation of portable flat-panel x-ray detector devices able to provide real-time readout, processing, and display of medical images. As a result, digital radiography flat-panel detectors are rapidly replacing computed radiography passive detectors for projection imaging exams and image intensifier detectors for dynamic fluoroscopy exams. Advanced exam capabilities now include digital tomosynthesis and dual-energy radiography; the former is based on rapid acquisition of multiple angle-dependent image projections to synthesize tomographic slabs at selectable depths within the patient, and the latter is based on rapid back-to-back acquisition of the same anatomy at low and high x-ray energies to generate separate soft tissue and bone images. In both situations, superimposition of anatomy is reduced or eliminated, with the possibility of enhanced diagnostic confidence. Increased x-ray absorption efficiency and lower electronic noise of digital radiography detectors compared to computed radiography detectors enable equal image quality at lower patient dose; however, because of a disconnect between image appearance and radiation dose, lower patient dose is not always achieved. Education, training, and implementation of standards such as the International Electrotechnical Commission 62494-1 Digital Radiography Exposure Index are needed to ensure image quality at the lowest appropriate radiation dose. The National Council on Radiation Protection and Measurements can contribute to radiation responsibility in medical imaging by providing guidance on use of digital radiography, including recommendations for acquisition protocols and exposure index standards, for development of radiographic exam diagnostic reference levels, and for oversight of retake and reject analysis.
Benefits and Risks in Medical Imaging
Authors: Zanzonico Pat B.
Published: December 2018

Ionizing radiation has contributed enormously to dramatic improvements in medical care. The potential risks of radiation-based medical imaging have, however, drawn considerable attention in recent years. Although such concern is beneficial in terms of critical evaluation and optimization of imaging procedures, it can create the misconception that radiation is the only risk of medical imaging. In contrast to expression of radiation risks, quantitative estimates of the benefits of medical imaging are notably lacking. Expression of benefit in purely qualitative terms vs. expression of risk in quantitative, and thus apparently more concrete, terms may contribute to a biased judgement of the relative benefits and risks of medical imaging among health care professionals as well as the public. This paper, therefore, quantitatively compares the benefits of diagnostic imaging in several cases, based on actual mortality or morbidity data if ionizing radiation were not employed, with the linear no-threshold model derived (i.e., theoretical) estimates of radiogenic cancer mortality and illustrates the large benefit-to-risk ratios typical of medical imaging procedures.
Dry Eye Symptoms May Have Association With Psychological Stress in Medical Students
Authors: Hyon Joon Young , Yang Hee Kyung , Han Sang Beom
Published: December 2018

Purpose:

To evaluate the prevalence and risk factors of symptomatic dry eye disease (DED) among medical students.

Methods:

This cross-sectional study included 209 students at a medical school in Korea. Dry eye symptoms were assessed using a 9-item questionnaire, and DED was defined as having one or more dry eye symptoms often or all the time. The ocular surface disease index (OSDI) and visual analog scale (VAS) questionnaires were also administered to quantify the dry eye symptoms. A survey including demographic data, potential risk factors for DED, personal habits, and psychological stress was also performed.

Results:

Of the 209 students, 188 (93 men and 95 women) completed the survey. The average age was 28.0±2.5 (mean±SD; range, 23–37) years. Prevalence of DED was 27.1% (51/188). Participants with DED had significantly higher VAS and OSDI than those without DED (P<0.001 for both). Univariate analysis revealed that female sex (P=0.001), contact lens (CL) wear (P=0.034), prolonged computer use (P=0.001), and higher psychological stress score (P<0.001) had significant association with DED. Multivariate analysis also showed the significant association between DED and female sex (P=0.026), CL wear (P=0.042), prolonged computer use (P=0.004), and higher stress score (P=0.014).

Conclusions:

Symptomatic DED was prevalent among medical students. Increased psychological stress was associated with higher risk of DED. Its risk also increased among women, CL wearers, and prolonged computer users.
Somatosensory profiles in acute herpes zoster and predictors of postherpetic neuralgia
Authors: Kramer Sybille , Baeumler Petra , Geber Christian , Fleckenstein Johannes , Simang Michael , Haas Laura , Schober Gabriel , Pfab Florian , Treede Rolf-Detlef , Irnich Dominik
Published: December 2018

This prospective cohort study aimed to characterize the sensory profile during acute herpes zoster (AHZ) and to explore sensory signs as well as physical and psychosocial health as predictors for postherpetic neuralgia (PHN). Results of quantitative sensory testing of 74 patients with AHZ at the affected site and at the distant contralateral control site were compared to a healthy control group. Pain characteristics (Neuropathic Pain and Symptom Inventory and SES), physical functioning, and psychosocial health aspects (Pain Disability Index, SF-36, and STAI) were assessed by questionnaires. Patients with PHN (n = 13) at 6-month follow-up were compared to those without PHN (n = 45). Sensory signs at the affected site were thermal and vibratory hypesthesia, dynamic mechanical allodynia (DMA), pressure hyperalgesia, and high wind-up (18%-29%), as well as paradoxical heat sensations and pinprick hypalgesia (13.5%). The unaffected control site exhibited thermal and vibratory hypesthesia, DMA, and pressure hyperalgesia. Dynamic mechanical allodynia and pinprick hypalgesia were mutually exclusive. Postherpetic neuralgia was associated with DMA (38.5% vs 6.7%; P = 0.010) and vibratory hypesthesia (38.5% vs 11.1%; P = 0.036) at the control site, with mechanical gain and/or loss combined with normal thermal detection (affected site: 69.2% vs 31.1%; P = 0.023; control site: 53.8% vs 15.5%; P = 0.009). Pain Disability Index (P = 0.036) and SES affective pain perception scores (P = 0.031) were over 50% higher, and 6 of 8 SF-36 subscores were over 50% lower (P < 0.045) in PHN. Sensory profiles in AHZ indicate deafferentation and central but not peripheral sensitization. Sensory signs at distant body sites, strong affective pain perception, as well as reduced quality of life and physical functioning in the acute phase may reflect risk factors for the transition to PHN.
Clustering a large Spanish sample of patients with fibromyalgia using the Fibromyalgia Impact Questionnaire–Revised: differences in clinical outcomes, economic costs, inflammatory markers, and gray matter volumes
Authors: Pérez-Aranda Adrián , Andrés-Rodríguez Laura , Feliu-Soler Albert , Núñez Christian , Stephan-Otto Christian , Pastor-Mira María A. , López-Roig Sofía , Peñacoba Cecilia , Calandre Elena P. , Slim Mahmoud , Salgueiro Monika , Feixas Guillem , Luciano Juan V.
Published: December 2018

The main objective of this study is to identify fibromyalgia syndrome (FMS) clusters using the Revised Fibromyalgia Impact Questionnaire (FIQR), and to examine whether the clusters differ in sociodemographic characteristics, clinical measures, direct and indirect costs, levels of inflammatory markers, and brain morphometry. A hierarchical cluster analysis was performed to classify a large, pooled Spanish sample of patients with FMS (N = 947) using the FIQR as clustering variable. A latent profile analysis was subsequently conducted to confirm the optimal number of FMS clusters. To examine external validity, a battery of clinical measures, economic costs, inflammatory markers, and gray matter volumes of relevant cortical and subcortical areas were analyzed. We also compared the discriminant validity of the clusters with the original FIQR severity categories. To promote the implementation in real-world clinical practice, we built a free online cluster calculator. Our findings indicated that a four-cluster solution more clearly captured the heterogeneity of FIQR data and provided the best fit. This cluster solution allowed for detection of differences for most clinical outcomes and economic costs. Regarding the inflammatory and brain-based biomarkers, differences were found in C-reactive protein, and tendencies were found in the right medial prefrontal cortex, the right parahippocampal gyrus, and the right middle cingulate cortex; brain regions associated with executive functions and pain processing. The original FIQR categories presented similar results, although their precision in discriminating among the nonextreme categories (ie, moderate and severe) was not sound. These findings are discussed in relation to previous research on FMS clustering.
The Cardiovascular Reserve Index—A Noninvasive Clinical Insight Into Heat Intolerance
Authors: Schiffmann Nathan , Schermann Haggai , Mazgaoker Savyon , Shaulov Yafim , Gabbay Uri , Epstein Yoram , Yanovich Ran
Published: December 2018

Objective:

To noninvasively explore the heat intolerance condition during exercise-heat stress by assessing cardiovascular (CV) performance.

Design:

Prospective study of participants undergoing a standard heat-tolerance test (HTT).

Setting:

Institutional study.

Participants:

Ninety-five young males: 16 heat-intolerant (HI) and 79 heat-tolerant (HT).

Interventions:

Cardiovascular performance during an HTT was estimated by heart rate (HR) and blood pressure measurements.

Main Outcome Measures:

The sensitivity of the cardiovascular reserve index (CVRI) and the dynamic heart rate reserve (dHRR) index to predict heat intolerance was compared.

Results:

A significant difference in the CV reserve during exercise-heat stress was exhibited between the HI and the HT groups. Starting at a similar level, the reduction in the CV reserve at HTT endpoint was much greater in the HI than the HT individuals (P < 0.0001), as depicted by both the CVRI and the dHRR. This result indicates a greater utilization of the CV reserve by HI individuals. The CVRI is likely to be better predictor of heat intolerance than the dHRR because the partial area under the curve in the high sensitivity (>90%) region of its receiver operating characteristic curve is higher (93.2 vs 76.8).

Conclusions:

More than being a predictor, the CVRI may provide a new clinical insight into heat intolerance because it noninvasively characterizes the efficiency of an individual's thermoregulatory mechanism and hints that an impaired CV reserve might underlie heat intolerance. The CVRI provides a noninvasive measurement of thermoregulation, which has been long awaited to enable on-field studies and dynamic monitoring of heat-exposed task forces.