bluuebunny/crossref_metadata_2025 huggingface dataset:
Disparities in accessibility to evidence‐based breast cancer care facilities by rural and urban areas in Bavaria, Germany
Authors: Stangl Stephanie , Rauch Sebastian , Rauh Jürgen , Meyer Martin , Müller‐Nordhorn Jacqueline , Wildner Manfred , Wöckel Achim , Heuschmann Peter U.
Published: April 2021

Background

Breast cancer (BC), which is most common in elderly women, requires a multidisciplinary and continuous approach to care. With demographic changes, the number of patients with chronic diseases such as BC will increase. This trend will especially hit rural areas, where the majority of the elderly live, in terms of comprehensive health care.

Methods

Accessibility to several cancer facilities in Bavaria, Germany, was analyzed with a geographic information system. Facilities were identified from the national BC guideline and from 31 participants in a proof‐of‐concept study from the Breast Cancer Care for Patients With Metastatic Disease registry. The timeframe for accessibility was defined as 30 or 60 minutes for all population points. The collection of address information was performed with different sources (eg, a physician registry). Routine data from the German Census 2011 and the population‐based Cancer Registry of Bavaria were linked at the district level.

Results

Females from urban areas (n = 2,938,991 [ie, total of females living in urban areas]) had a higher chance for predefined accessibility to the majority of analyzed facilities in comparison with females from rural areas (n = 3,385,813 [ie, total number of females living in rural areas]) with an odds ratio (OR) of 9.0 for cancer information counselling, an OR of 17.2 for a university hospital, and an OR of 7.2 for a psycho‐oncologist. For (inpatient) rehabilitation centers (OR, 0.2) and genetic counselling (OR, 0.3), women from urban areas had lower odds of accessibility within 30 or 60 minutes.

Conclusions

Disparities in accessibility between rural and urban areas exist in Bavaria. The identification of underserved areas can help to inform policymakers about disparities in comprehensive health care. Future strategies are needed to deliver high‐quality health care to all inhabitants, regardless of residence.
3D Hydrangea‐like InVO4/Ti3C2Tx Hierarchical Heterosystem Collaborating with 2D/2D Interface Interaction for Enhanced Photocatalytic CO2 Reduction
Authors: Li Liang , Yang Yong , Yang Liuqing , Wang Xiaoyong , Zhou Yong , Zou Zhigang
Published: April 2021

3D hydrangea‐like InVO4/Ti3C2Tx heterosystem is fabricated by in‐situ growth of InVO4 on Ti3C2Tx and on spot self‐assembly. The formation of a hierarchical architecture collaborating with well‐defined 2D/2D interfacial interaction is constructed by optimizing the ratio of Ti3C2Tx incorporated in the formation of InVO4. The as‐obtained InVO4/Ti3C2Tx presents improved photon trapping capacity and exposure of reactive sites owing to the enhanced BET specific surface areas, and the capture capacity towards CO2 is strengthened coordinated with the basic feature of Ti3C2Tx. Based on DFT calculations, the electron transfer from InVO4 to Ti3C2Tx is demonstrated, and the unique 2D/2D interface interaction in InVO4/Ti3C2Tx heterosystem efficiently improves the separation of photogenerated charge carriers. As a result, the 3D hierarchical InVO4/Ti3C2Tx heterosystem presents 13.83 μmol g−1 h−1 of CO production (3.1‐folds of pristine InVO4) with 92% selectivity and superior stability. The 3D hierarchical design collaborating with 2D/2D interfacial interaction provides a new avenue to develop ideal catalysts for artificial photosynthesis.
Bridging the Gap: From Homogeneous to Heterogeneous Parahydrogen‐induced Hyperpolarization and Beyond
Authors: Chekmenev Eduard Y. , Goodson Boyd M. , Bukhtiyarov Valerii I. , Koptyug Igor V.
Published: April 2021

Demonstration of parahydrogen‐induced polarization effects in hydrogenations catalyzed by heterogeneous catalysts instead of metal complexes in a homogeneous solution has opened an entirely new dimension for parahydrogen‐based research, demonstrating its applicability not only for the production of catalyst‐free hyperpolarized liquids and gases and long‐lived non‐equilibrium spin states for potential biomedical applications, but also for addressing challenges of modern fundamental and industrial catalysis including advanced mechanistic studies of catalytic reactions and operando NMR and MRI of reactors. This essay summarizes the progress achieved in this field by highlighting the research contributed to it by our colleague and friend Kirill V. Kovtunov whose scientific career ended unexpectedly and tragically at the age of 37. His role in this research was certainly crucial, further enhanced by a vast network of his contacts and collaborations at the national and international level.
Supramolecular Sensing of Chemical Warfare Agents
Authors: Butera Ester , Zammataro Agatino , Pappalardo Andrea , Trusso Sfrazzetto Giuseppe
Published: April 2021

Chemical warfare agents are a class of organic molecules used as chemical weapons due to their high toxicity and lethal effects. For this reason, the fast detection of these compounds in the environment is crucial. Traditional detection methods are based on instrumental techniques, such as mass spectrometry or HPLC, however the use of molecular sensors able to change a detectable property (e. g., luminescence, color, electrical resistance) can be cheaper and faster. Today, molecular sensing of chemical warfare agents is mainly based on the “covalent approach”, in which the sensor reacts with the analyte, or on the “supramolecular approach”, which involves the formation of non‐covalent interactions between the sensor and the analyte. This Review is focused on the recent developments of supramolecular sensors of organophosphorus chemical warfare agents (from 2013). In particular, supramolecular sensors are classified by function of the sensing mechanism: i) Lewis Acids, ii) hydrogen bonds, iii) macrocyclic hosts, iv) multi‐topic sensors, v) nanosensors. It is shown how the supramolecular non‐covalent approach leads to a reversible sensing and higher selectivity towards the selected analyte respect to other interfering molecules.
Towards Foldameric Miniproteins: A Helix‐Turn‐Helix Motif
Authors: Ożga Katarzyna , Drewniak‐Świtalska Magda , Rudzińska‐Szostak Ewa , Berlicki Łukasz
Published: April 2021

Numerous beta‐amino acid containing peptides forming secondary structures have been already described, however the design of higher‐order structures remains poorly explored. The methodology allowing construction of sequence patterns containing few rigid secondary element was proposed and experimentally validated. On the basis of 9/10/9/12‐helix containing cis‐2‐aminocyclopentanecarboxylic acid (cis‐ACPC) residues arranged in an ααββ sequence pattern, a conformationally stable helix‐turn‐helix structure was designed. The connection between two helices was also constructed using cis‐ACPC residues. Five examples of designed peptides were obtained and analyzed using circular dichroism and nuclear magnetic resonance spectroscopy, which confirmed the assumed way of folding. The NMR structure was calculated for the peptide with the highest number of non‐sequential contacts.
The effect of hypnosis on pain relief due to injection of dental infiltration anesthesia
Authors: Arabzade Moghadam Soma , Yousefi Fayegh , Saad Sahand
Published: April 2021

Background and objective

Dental patients often experience the fear of pain induced by injectable anesthesia. This study aimed to investigate the impact of hypnosis on relieving the pain of injected dental infiltration anesthesia.

Materials and methods

This single‐blind clinical trial was conducted on 32 healthy volunteers to assess the pain perception in mucosal injection. The visual analog scale was applied for the measurement of one‐sided pain intensity in the maxilla without hypnosis. When hypnosis was implemented, the same procedure was performed on the other side of the maxilla reversely within one session.

Results

Hypnosis implementation significantly decreased the intensity of the perceived pain before anesthesia injection (p = 0.05).

Conclusion

Hypnosis before the injection of dental infiltration anesthesia could decrease the pain intensity caused by the injection. Therefore, hypnosis therapy is recommended as an effective approach to pain control for anesthesia injection.
Co‐Catalyzed Synthesis of Primary Amines via Reductive Amination employing Hydrogen under very mild Conditions
Authors: Elfinger Matthias , Schönauer Timon , Thomä Sabrina L. J. , Stäglich Robert , Drechsler Markus , Zobel Mirijam , Senker Jürgen , Kempe Rhett
Published: April 2021

Nanostructured and reusable 3d‐metal catalysts that operate with high activity and selectivity in important chemical reactions are highly desirable. Here, a cobalt catalyst was developed for the synthesis of primary amines via reductive amination employing hydrogen as the reducing agent and easy‐to‐handle ammonia, dissolved in water, as the nitrogen source. The catalyst operates under very mild conditions (1.5 mol% catalyst loading, 50 °C and 10 bar H2pressure) and outperforms commercially available noble metal catalysts (Pd, Pt, Ru, Rh, Ir). A broad scope and a very good functional group tolerance were observed. The key for the high activity seemed to be the used support: an N‐doped amorphous carbon material with small and turbostratically disordered graphitic domains, which is microporous with a bimodal size distribution and with basic NH functionalities in the pores.
An analytical gm/ID‐based harmonic distortion prediction method for multistage operational amplifiers
Authors: Xie Qixu , Shi Guoyong
Published: April 2021

An analytical stage‐based harmonic distortion (HD) analysis method for multistage operational amplifiers (Op Amps) is developed in this work. This work contributes two fundamental methods that make the analytical HD prediction possible at the circuit level. Firstly, we propose that the traditionally used first order small‐signal transistor quantities gm (transconductance) and go (output conductance) in the gm/ID design methodology for bulk complementary metal‐oxide‐semiconductor (CMOS) technology can be extended to the higher order quantities gm(k) and go(k) (
). With proper normalization, these quantities become neutral to the device dimensions and operation currents, hence can be precharacterized by sweeping simulations and used as lookup tables. Secondly, we further develop analytical nonlinearity expressions for a set of commonly used amplifier stages, represented as the functions of the nonlinearity parameters gm(k) and go(k) of the transistors that form a stage circuit. A combination of these two fundamental methods on hierarchical nonlinearity modeling enables us to apply the existing analytical HD estimation methods for the stage‐form macromodels to predict the circuit‐level HD behavior, overcoming the need of running repeated simulations under device resizing and rebiasing. The proposed harmonic distortion analysis method has been validated by application to real multistage amplifiers, achieving HD prediction results in excellent agreement to fully transistor‐level circuit simulation results but with substantial speedup.
Ancestral ecological regime shapes reaction to food limitation in the Least Killifish,Heterandria formosa
Authors: Felmy Anja , Leips Jeff , Travis Joseph
Published: April 2021

Populations with different densities often show genetically based differences in life histories. The divergent life histories could be driven by several agents of selection, one of which is variation in per‐capita food levels. Its relationship with population density is complex, as it depends on overall food availability, individual metabolic demand, and food‐independent factors potentially affecting density, such as predation intensity. Here, we present a case study of two populations of a small live‐bearing freshwater fish, one characterized by high density, low predation risk, low overall food availability, and presumably low per‐capita food levels, and the other by low density, high predation risk, high overall food availability, and presumably high per‐capita food levels. Using a laboratory experiment, we examined whether fish from these populations respond differently to food limitation, and whether size at birth, a key trait with respect to density variation in this species, is associated with any such differential responses. While at the lower food level growth was slower, body size smaller, maturation delayed, and survival reduced in both populations, these fitness costs were smaller in fish from the high‐density population. At low food, only 15% of high‐density fish died, compared to 75% of low‐density fish. This difference was much smaller at high food (0% vs. 15% mortality). The increased survival of high‐density fish may, at least partly, be due to their larger size at birth. Moreover, being larger at birth enabled fish to mature relatively early even at the lower food level. We demonstrate that sensitivities to food limitation differ between study populations, consistent with selection for a greater ability to tolerate low per‐capita food availability in the high‐density population. While we cannot preclude other agents of selection from operating in these populations simultaneously, our results suggest that variation in per‐capita food levels is one of those agents.
Tripartite parasitic and symbiotic interactions as a possible mechanism of horizontal gene transfer
Authors: Zhao Chaoyang , Miao Shaoming , Yin Yanfang , Zhu Yanjuan , Nabity Paul , Bansal Raman , Liu Chenxi
Published: April 2021

Herbivory is a highly sophisticated feeding behavior that requires abilities of plant defense suppression, phytochemical detoxification, and plant macromolecule digestion. For plant‐sucking insects, salivary glands (SGs) play important roles in herbivory by secreting and injecting proteins into plant tissues to facilitate feeding. Little is known on how insects evolved secretory SG proteins for such specialized functions. Here, we investigated the composition and evolution of secretory SG proteins in the brown marmorated stink bug (Halyomorpha halys) and identified a group of secretory SG phospholipase C (PLC) genes with highest sequence similarity to the bacterial homologs. Further analyses demonstrated that they were most closely related to PLCs of Xenorhabdus, a genus of Gammaproteobacteria living in symbiosis with insect‐parasitizing nematodes. These suggested that H. halys might acquire these PLCs from Xenorhabdus through the mechanism of horizontal gene transfer (HGT), likely mediated by a nematode during its parasitizing an insect host. We also showed that the original HGT event was followed by gene duplication and expansion, leading to functional diversification of the bacterial‐origin PLC genes in H. halys. Thus, this study suggested that an herbivore might enhance adaptation through gaining genes from an endosymbiont of its parasite in the tripartite parasitic and symbiotic interactions.
Electrochemical Tandem Cyclization of Unsaturated Oximes with Diselenides: A General Approach to Seleno Isoxazolines Derivatives with Quaternary Carbon Center
Authors: Gao Wenchao , Li Beibei , Zong Luyi , Yu Lintao , Li Xuyang , Li Qiyang , Zhang Xu , Zhang Sheng , Xu Kun
Published: April 2021

Electrochemical oxidative tandem cyclization of unsaturated oximes with diselenides has been developed to provide a general access to seleno isoxazolines containing a quaternary carbon center (35 examples). This novel protocol features with mild reaction conditions (metal‐ and oxidant‐free), good functional group tolerance and promising scalability. Moreover, plausible reaction pathways have been proposed.
On the design and implementation of efficient antennas for high frequency‐radio frequency identification read/write devices
Authors: Ofosu Addo Ernest , Kommey Benjamin , Selasi Agbemenu Andrew , Kumbong Hermann
Published: April 2021

This article describes an in‐depth methodical approach to the development of efficient high‐frequency (HF) antennas for use in radio frequency identification (RFID) systems operating at 13.56 MHz. It presents brief theory relevant to RFID communication and sets up a framework within which features and requirements of antennas are linked to key design parameters such as antenna form‐factor and size; RF power level, material and communication protocol. Tuning circuits necessary to adjust the resonance and power matching characteristics of antennas for good transponder interrogation and response recovery are discussed. To validate the approaches outlined, a stepwise design and measurement of an HF antenna for an ISO/IEC 15693 compliant read/write device (RWD) is described. Common practical problems that are often encountered in such design processes are also commented on. The prototyped antenna was tuned, connected to the RWD via a 50 coaxial cable and tested.
Markov chain Monte Carlo methods for hierarchical clustering of dynamic causal models
Authors: Yao Yu , Stephan Klaas E.
Published: April 2021

In this article, we address technical difficulties that arise when applying Markov chain Monte Carlo (MCMC) to hierarchical models designed to perform clustering in the space of latent parameters of subject‐wise generative models. Specifically, we focus on the case where the subject‐wise generative model is a dynamic causal model (DCM) for functional magnetic resonance imaging (fMRI) and clusters are defined in terms of effective brain connectivity. While an attractive approach for detecting mechanistically interpretable subgroups in heterogeneous populations, inverting such a hierarchical model represents a particularly challenging case, since DCM is often characterized by high posterior correlations between its parameters. In this context, standard MCMC schemes exhibit poor performance and extremely slow convergence. In this article, we investigate the properties of hierarchical clustering which lead to the observed failure of standard MCMC schemes and propose a solution designed to improve convergence but preserve computational complexity. Specifically, we introduce a class of proposal distributions which aims to capture the interdependencies between the parameters of the clustering and subject‐wise generative models and helps to reduce random walk behaviour of the MCMC scheme. Critically, these proposal distributions only introduce a single hyperparameter that needs to be tuned to achieve good performance. For validation, we apply our proposed solution to synthetic and real‐world datasets and also compare it, in terms of computational complexity and performance, to Hamiltonian Monte Carlo (HMC), a state‐of‐the‐art Monte Carlo technique. Our results indicate that, for the specific application domain considered here, our proposed solution shows good convergence performance and superior runtime compared to HMC.
Biological Nanotherapeutics for Liver Disease
Authors: Driscoll Julia , Wehrkamp Cody , Ota Yu , Thomas Jonathan N. , Yan Irene K. , Patel Tushar
Published: April 2021

Extracellular vesicles (EVs) are a heterogeneous group of biological nano‐sized vesicles that are released from cells and contribute to intercellular communication. Emerging knowledge about their biogenesis, composition, release, and uptake has resulted in broad interest in elucidating their potential roles in disease pathophysiology. The distinct biological properties of these biological nanoparticles emphasize several appealing advantages for potential therapeutic applications compared with the use of synthetic nanoparticles. When administered systemically, EVs are taken up and sequestered within the liver, further emphasizing opportunities for therapeutic use. Consequently, there is growing interest in their use for liver diseases. EVs can be used directly as therapeutics, and several studies have highlighted the intrinsic therapeutic properties of mesenchymal stem cell–derived EVs for chronic and acute liver diseases. Alternatively, EVs can be modified to facilitate their use for the delivery of therapeutic cargo. In this review, we discuss the cellular sources of EV, provide a concise overview of their potential use in diverse processes, and outline several promising applications for the use of EV‐based therapeutics for liver diseases. The use of EV‐based therapeutics provides a viable approach to target hepatic pathophysiology.
Transitioning from university to postgraduate medical training: A narrative review of work readiness of medical graduates
Authors: Padley James , Boyd Sarah , Jones Alison , Walters Lucie
Published: April 2021

Context

Work readiness is often described in terms of the clinical competence medical graduates bring to day 1 of internship. Despite being increasingly viewed as a key graduate outcome, work readiness has remained poorly defined.

Objective

This narrative review draws on the international literature to explore how different research methods provide differing insight into what constitutes work readiness of medical graduates. From this, we explored contributory factors and developed a conceptual framework to better understand work readiness.

Methods

Databases were searched using the terms including “ready,” “readiness,” “preparedness,” “medical graduates,” “intern,” and “junior doctor.” Information was summarized using a textual description template that included information on study setting, participants, methodologies, limitations, and key result areas (including measures/themes and study conclusions). Consensus discussions between authors led to the naming and understanding of the key themes.

Results

Seventy studies were included in the review. Study participants included final‐year medical students (n = 20), junior doctors early in internship (n = 24), and junior doctors late in internship or postgraduate year 2 and above (n = 23). Most studies explored work readiness through the retrospective self‐report of the students and/or junior doctor participants. Quantitative research methods elaborated on key skills‐based competencies, whereas qualitative research methods provided insight into key contextual and individual characteristics that contributed to preparedness.

Conclusions

Different research methods provided insight into competencies, as well as individual and contextual aspects, associated with preparedness for practice. The transition from university to clinical practice is significant and requires personal capability and confidence, as well as a supportive training context. Enabling students to engage authentically in clinical environments enhanced preparedness by promoting understanding of role and responsibility. Individual resilience is important, but contextual factors, including provision of adequate support and feedback, can enhance or subtract from feeling prepared. We propose a novel conceptual framework for better understanding work readiness.
Synthesis of O‐linked Cyclitol Analogues of Gilvocarcin M and Antibacterial Activity
Authors: Sharif Ehesan U. , Shi Pei , O'Doherty George A.
Published: April 2021

Two unnatural regioisomeric glycosylated Gilvocarcin analogues were proposed as model compounds to study the origin behind the biosynthetic development of the Gilvocarcins, a class of bioactive C‐aryl glycoside natural products. More specifically, the origins behind the proposed O‐ to C‐glycoside migration in the evolution of the biosynthesis for these classes of Angucycline antibiotic natural products. For stability reasons a 5a‐carbasugar motif was used to mimic the sugar portion of the molecule and of synthetic ease the proposed abiotic rearrangement move the sugar analogue along with its O‐glycoside linkage. The two proposed regioisomeric analogues were synthesized by a regio‐divergent synthetic pathway and featured a Mitsunobu‐like invertive cyclictolization reaction to install the carbasugar motif. The two regioisomeric Gilvocarcin analogues were evaluated as antibiotic with Gilvocarcin M as a control. Only one of the two isomers showing weak antibiotic activity as compared to Gilvocarcin M.
Strategic targeting of non‐small‐cell lung cancer utilizing genetic material‐based delivery platforms of nanotechnology
Authors: Chaudhary Swati , Singh Amit , Kumar Pankaj , Kaushik Mahima
Published: April 2021

Several limitations of conventional cancer treatment such as non‐specific targeting, solubility problems, and ineffective entry of chemotherapeutics into cancer cells can be overcome by using nanotechnology targeted drug delivery systems. Some combinations of biomolecules and nanoparticles have proven to be excellent therapeutics for Non‐small cell lung cancer (NSCLC) in the last decades. Targeted gene delivery has shown in vivo as well as in vitro promising results with therapeutic efficacy. Gene therapy has shown enhanced transfection efficiency and better targeting potential on several NSCLC cell lines. Still, there are several challenges in nanoparticle‐mediated gene therapy, which include stability of biomolecules and nanoparticles during delivery, managing their biodistribution, and reducing the possible cytotoxic effects of the nanoparticles, which need to be solved before clinical trials. Evaluation of therapeutic efficacy of biomolecules and nanoparticle combination in gene therapy must be established to expand the application of nano‐gene therapy in cancer treatment.
Association of an insertion mutation in PRRT2 with hereditary spastic paraplegia accompanied by polyneuropathy
Authors: Wang Zhaoyu , Dong Huijie , Ji Xiaofei , Luan Siyu , Cao Hua
Published: April 2021

Background

Hereditary spastic paraplegia is a rare familial hereditary neurodegenerative disease caused by multiple autosomal dominant mutations. More than 50 mutant genes have been reported to be associated with this disease.

Methods

In this study, we have reported a rare insertion mutation site in PRRT2 that caused a familial disorder of hereditary spastic paraplegia accompanied by polyneuropathy.

Results

We used second‐generation sequencing of samples of the proband's familial genome and found an insertion mutation of C/CC in NM_001256443:c.641dupC that was localized to the second exon of PRRT2. This functional mutation can cause an amino acid sequence change (arginine >proline) and dysfunctional neuronal transmembrane proteins, which might have been related to the onset of hereditary spastic paraplegia accompanied by polyneuropathy in the family reported in this study.

Conclusion

The discovery of this mutation site provides an important theoretical basis for specific gene‐based diagnosis and treatment of hereditary spastic paraplegia.
Opportunities to improve nitrogen use efficiency in an intensive vegetable system without compromising yield
Authors: Suter Helen , Pandey Arjun , Lam Shu Kee , Davies Rohan , Hassan Rifaath , Riches David , Chen Deli
Published: April 2021

Intensive vegetable cropping systems rely heavily on nitrogen (N) inputs from multiple synthetic and organic fertilizer applications. The majority of applied N is lost to the environment through numerous pathways, including as nitrous oxide (N2O). A field trial was conducted to examine the opportunities to reduce N input in an intensive vegetable system without compromising yield. Treatments applied were control (no N), manure (M, 408 kg N ha–1 from chicken manure), grower practice (GP, 408 kg N ha–1 from chicken manure + 195 kg N ha–1 from fertilizer), and 2/3 GP (two‐thirds of the total N input in GP), all with and without 3,4‐dimethylpyrazole phosphate (DMPP). Nitrogen recovery in the GP treatment was determined using 15N‐labeled fertilizer. Using only manure significantly lowered celery (Apium graveolens L.) yield and apparent N use efficiency (ANUE) compared with GP. Reducing N input by one‐third did not affect yield or ANUE. Use of DMPP increased ANUE despite no yield improvement. More than 50% of the applied N in the GP treatment was lost to the environment, with almost 10 kg N ha–1 emitted as N2O over the season, which was 67 times more than from the control. Reducing the N input by one‐third or using manure only reduced N2O emissions by more than 70% relative to GP. This study shows that there is a clear opportunity to reduce N input and N2O emissions in high‐fertilizer‐input vegetable systems without compromising vegetable yield.
The structure of graphs with no W4 immersion
Authors: DeVos Matt , Malekian Mahdieh
Published: April 2021

This paper gives a precise structure theorem for the class of graphs which do not contain as an immersion. This strengthens a previous result of Belmonte et al. that gives a rough description of this class. In fact, we prove a stronger theorem concerning rooted immersions of where one terminal is specified in advance. This stronger result is key in a forthcoming structure theorem for graphs with no immersion.
Diagnostic Performance of a Lower‐dose Contrast‐Enhanced 4D Dynamic MR Angiography of the Lower Extremities at 3 T Using Multisegmental Time‐Resolved Maximum Intensity Projections
Authors: Raczeck Paul , Fries Peter , Massmann Alexander , Minko Peter , Frenzel Felix , Woerner Tobias , Buecker Arno , Schneider Guenther K.
Published: April 2021

Background

For peripheral artery disease (PAD), MR angiography (MRA) is a well‐established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this.

Purpose

To evaluate the diagnostic accuracy of time‐resolved 4D MR‐angiography with interleaved stochastic trajectories (TWIST‐MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent.

Study Type

Retrospective.

Population

Forty adult PAD patients yielding 1088 artery segments.

Field Strength/Sequence

A 3.0 T, time‐resolved 4D MR‐angiography with TWIST‐MRA and MIP of dynamic images.

Assessment

DSA was available in 14 patients (256 artery segments) and used as reference standard. Three‐segmental MIP reconstructions of TWIST‐images after administration of 3 mL of gadolinium‐based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers.

Statistical Tests

Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver‐operating‐characteristics (ROC) curves (AUCs) with the DeLong method. Bland–Altman‐comparison.

Results

High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3–99.9% (95%‐CI)] and specificity 98.5% [95.7–99.8% (95%‐CI)]) and artery occlusion (sensitivity 93.1% [77.2–99.2% (95%‐CI)] and specificity 99.1% [96.9–99.9% (95%‐CI)]). Inter‐reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71–0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]).

Data Conclusion

MIPs of dynamic TWIST‐MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium‐based contrast agents for the entire runoff vasculature.

Evidence Level

3

Technical Efficacy

Stage 2
Digital radiography reject analysis of examinations with multiple rejects: an Australian emergency imaging department clinical audit
Authors: Stephenson‐Smith Brittany , Neep Michael J , Rowntree Pamela
Published: April 2021

Introduction

The largest source of manmade ionising radiation exposure to the public stems from diagnostic medical imaging examinations. Reject analysis, a form of quality assurance, was introduced to minimise repeat exposures. The purpose of this study was to analyse projection‐specific reject rates and radiographic examinations with multiple rejects.

Methods

A retrospective audit of rejected radiographs was undertaken in a busy Australian metropolitan emergency digital X‐ray room from March to June 2018. The data were collected by reject analysis software embedded within the X‐ray unit. Reject rates, and reasons for rejection for each X‐ray projection were analysed.

Results

Data from 11, 596 images showed overall reject rate was 10.3% and the overall multiple reject rate was 1.3%. The projections with both a high number and high percentage of rejects were antero‐posterior (AP) chest (175, 18.1%), AP pelvis (78, 22.5%), horizontal beam hip (61, 33.5%) and horizontal beam knee (116, 30.5%). The projections with both a high frequency and multiple reject rate were horizontal beam knee (32, 8.4%) and horizontal beam hip (17, 9.3%). The top reasons for multiple rejects were positioning (67.1%) and anatomy cut‐off (8.4%).

Conclusions

The findings of this study demonstrated that projection‐specific reject and multiple reject analysis in digital radiography is necessary in identifying areas for quality improvement which will reduce radiation exposure to patients. Projections that were frequently repeated in this study were horizontal beam knee and horizontal beam hip. Future research could involve re‐auditing the department following the implementation of improvement strategies to reduce unnecessary radiation exposure.
Influence of the modes of climate variability in the Tropical Pacific and Atlantic on accumulated rainfall and reservoir water volumes in the Northeast Brazil
Authors: dos Santos Gomes Rafaela , Lima Kellen Carla
Published: April 2021

The volumes of artificial reservoirs as well as the accumulated rainfall over the Northeast region of Brazil (NEB) are sensible to the modes of climate variability. Thus, the objective of this study is to identify the relationship between the spatial patterns of the modes of climate variability in the Tropical Atlantic and Pacific Oceans, and the homogeneous rainfall subregions affecting the recharge of the water volumes of reservoirs in the NEB during the period from 1986 to 2018. For this end, we used monthly rainfall; monthly water volume data for artificial reservoirs; sea surface temperature anomalies in the Tropical Pacific and Tropical Atlantic Ocean. The first step was to apply cluster analysis to subdivide the NEB according to the monthly rainfall climatology. After, the technique of synthetic maximum rainfall series was applied. Then, the response time between rainfall climatology and reservoir water volume climatology was identified by means of cross‐correlation. Finally, the partial least squares regression was applied to infer the relationship between synthetic maximum rainfall series in each subregion and the modes of climate variability. Results showed that five homogeneous rainfall subregions with three distinct wet seasons. The synthetic time series of rainfall in the subregions were positively correlated with the climatology of the reservoir volumes with lags of up to 5 months after the beginning of the series. Both rainfall and the water volume of artificial reservoirs were sensible to the modes of climate variability of the studied oceans.
Attention‐Deficit/Hyperactivity Disorder Symptoms, Perceived Stress, and Resilience in College Students
Authors: Hamilton Stacey L. , Baraldi Amanda , Kennison Shelia M.
Published: April 2021

This research investigated the relationships among symptoms associated with attention‐deficit/hyperactivity disorder (ADHD), perceived stress, and resilience in college students. In our study of 558 college students (175 men, 383 women), we confirmed the hypothesis that the relationship between ADHD symptoms and perceived stress is mediated by protective factors associated with resilience. The relationships were not significantly moderated by sex. Implications for increasing resilience in college students and lowering perceived stress for college students are discussed.
Tracheotomy in COVID‐19 patients: A retrospective study on complications and timing
Authors: Pauli Nina , Eeg‐Olofsson Måns , Bergquist Henrik
Published: April 2021

Objectives

The aim of this study was to analyze the timing of tracheotomy and the duration of mechanical ventilation and stay in the intensive care unit (ICU) in patients with COVID‐19 infection. Furthermore, we aimed to investigate tracheotomy complications and mortality.

Methods

Consecutive patients with COVID‐19 infection admitted to the Department of Infectious Diseases in Gothenburg, Sweden were identified. Medical records were retrieved and retrospectively assessed.

Results

One hundred eighty‐eight patients with COVID‐19 infection requiring hospital care were identified. Of these, 116 patients were critically ill and intubated, and 55 patients underwent tracheotomy. The mean time from endotracheal intubation to tracheotomy was 12 days (range 5‐28 days). There was a correlation between the timing of tracheotomy and the duration of mechanical ventilation, where a shorter time between intubation and tracheotomy was correlated with a shorter duration of mechanical ventilation (r .58, P < .001), and a correlation was identified between the timing of tracheotomy and the duration of ICU stay (r .52, P < .001). Perioperative hypoxemia was registered in 9% of tracheotomies performed, whereas postoperative bleeding was observed in 27% of cases, the majority of which were minor.

Conclusions

This retrospective cohort study indicates that early tracheotomy is related to a reduced need for mechanical ventilation and a shorter duration of stay in the ICU in severe cases of COVID‐19 disease. Complications during and after tracheotomy in this specific cohort included risk perioperative hypoxia and postoperative bleeding. Prospective randomized controlled trials would be of value to confirm these findings.

Level of Evidence

4, Case series.
Scaling effects of a eutrophic river plume on organic carbon consumption
Authors: Chen Chung‐Chi , Gong Gwo‐Ching , Chiang Kuo‐Ping , Shiah Fuh‐Kwo , Chung Chih‐Ching , Hung Chin‐Chang
Published: April 2021

The amount of fluvial input has important impacts on shelf regions. To understand how the magnitude of fluvial discharge affects plume ecosystems, particularly organic carbon consumption, data over 10 consecutive summers (2003–2012) were examined in the Changjiang River plume of the East China Sea. The area of the Changjiang River plume ranged from approximately 4.90 × 103 km2 to 94.83 × 103 km2 and varied in proportion to the freshwater discharge rate. Plankton community respiration was at the medium to high end of the values reported for coastal regions. Total organic carbon consumption over the Changjiang River plume was positively correlated with the Changjiang freshwater discharge. This scaling relationship might be associated with river flows delivering allochthonous organic carbon and dissolved inorganic nutrients into the East China Sea. However, plankton community respiration (per m3 basis) decreased as the area of the Changjiang River plume increased; this rate appeared to have been influenced by particulate organic carbon (POC) levels and/or total plankton biomass. Even though POC was dominated by phytoplankton biomass allometrically, bacteria contributed more to plankton community respiration, possibly signifying that these bacteria were more reliant on plankton‐derived organic matter. Even with high phytoplankton biomass and primary productivity, this plume ecosystem was heterotrophic, albeit close to a state of carbon balance. To support high organic carbon consumption, in addition to allochthonous sources from fluvial runoff, a large amount of organic matter might have been autochthonous and derived from plankton in the Changjiang River plume.
Influence of settling organic matter quantity and quality on benthic nitrogen cycling
Authors: Albert Séréna , Bonaglia Stefano , Stjärnkvist Nellie , Winder Monika , Thamdrup Bo , Nascimento Francisco J. A.
Published: April 2021

Coastal sediments are major contributors to global carbon (C) mineralization and nutrient cycling and are tightly linked to processes in the pelagic environment. In this study, we aimed to investigate the regulating potential of quantity and quality of planktonic organic matter (OM) deposition on benthic metabolism, with a particular focus on nitrogen (N) cycling processes. We simulated inputs of spring (C : N 10.9) and summer (C : N 5.6) plankton communities in high and low quantities to sediment cores, and followed oxygen consumption, nutrient fluxes as well as nitrate reduction rates, that is, denitrification and dissimilatory nitrate reduction to ammonium for 10 d. Our results demonstrate the primary importance of OM quality in determining the fate of organic N once it settles to the sediment surface. Settling of N‐rich summer plankton material resulted in a ∼ twofold lower denitrification efficiency (40–56%) compared to N‐poor spring plankton (88–115%). This indicates that N‐rich plankton deposition favors recycling of inorganic nutrients to the water column over N‐loss via denitrification. OM quantity was positively related to mineralization activity, but this neither directly affected N fluxes nor denitrification activity, highlighting the complex interplay between the OM quantity and quality in regulating N cycling. In light of these new findings, we support the use of simple qualitative indicators such as C : N ratio of OM to investigate how future changes in benthic‐pelagic coupling might influence N budgets at the sediment–water interface.
Control of a phytoplankton bloom by wind‐driven vertical mixing and light availability
Authors: Hopkins Joanne E. , Palmer Matthew R. , Poulton Alex J. , Hickman Anna E. , Sharples Jonathan
Published: April 2021

The balance of physical and biological processes governing phytoplankton growth rates and the accumulation of biomass is widely debated in the literature, notably during the winter–spring transition. Here we show, in a temperate shelf sea that variability in the depth of the actively mixing surface layer is the leading order control. During a 2‐week period preceding the peak of the spring bloom we observe two distinct regimes; first, growth within the euphotic zone during the day and re‐distribution of new biomass to the seasonal pycnocline at night by convective mixing; then, more rapid biomass accumulation trapped within a shallower, wind‐driven actively mixing layer that was decoupled from the pycnocline below. Our observations of the bloom in the Celtic Sea, Northwest European Shelf, were made using ocean gliders and include measurements of the dissipation of turbulent kinetic energy. A 1‐D phytoplankton growth model driven by our measurements of dissipation and incident irradiance replicates the observed bloom and reinforces the conclusion that physical processes that mediate light availability were key. Day‐to‐day variability in cloud cover and the ability of phytoplankton to acclimate to their light environment were also important factors in determining growth rates, and the timing of the biomass peak. Our results emphasize the need for accurate turbulent mixing parameterizations in coupled hydrodynamic‐ecosystem models. Our findings are applicable to any region where wind‐driven mixing can modify nutrient and light availability, especially across subpolar shelves in the northern hemisphere where light rather than nutrients is typically the limiting factor on phytoplankton growth.
Toward resolving disparate accounts of the extent and magnitude of nitrogen fixation in the Eastern Tropical South Pacific oxygen deficient zone
Authors: Selden Corday R. , Mulholland Margaret R. , Widner Brittany , Bernhardt Peter , Jayakumar Amal
Published: April 2021

Examination of dinitrogen (N2) fixation in the Eastern Tropical South Pacific oxygen deficient zone has raised questions about the range of diazotrophs in the deep sea and their quantitative importance as a source of new nitrogen globally. However, technical considerations in the deployment of stable isotopes in quantifying N2 fixation rates have complicated interpretation of this research. Here, we report the findings of a comprehensive survey of N2 fixation within, above and below the Eastern Tropical South Pacific oxygen deficient zone. N2 fixation rates were measured using a robust 15N tracer method (bubble removal) that accounts for the slow dissolution of N2 gas and calculated using a conservative approach. N2 fixation was only detected in a subset of samples (8 of 125 replicated measurements) collected within suboxic waters (< 20 μmol O2 kg−1) or at the oxycline. Most of these detectable rates were measured at nearshore stations, or where surface productivity was high. These findings support the hypothesis that low oxygen/high organic carbon conditions favor non‐cyanobacterial diazotrophs. Nevertheless, this study indicates that N2 fixation is neither widespread nor quantitatively important throughout this region.
The extent and variability of storm‐induced temperature changes in lakes measured with long‐term and high‐frequency data
Authors: Doubek Jonathan P. , Anneville Orlane , Dur Gaël , Lewandowska Aleksandra M. , Patil Vijay P. , Rusak James A. , Salmaso Nico , Seltmann Christian Torsten , Straile Dietmar , Urrutia‐Cordero Pablo , Venail Patrick , Adrian Rita , Alfonso María B. , DeGasperi Curtis L. , de Eyto Elvira , Feuchtmayr Heidrun , Gaiser Evelyn E. , Girdner Scott F. , Graham Jennifer L. , Grossart Hans‐Peter , Hejzlar Josef , Jacquet Stéphan , Kirillin Georgiy , Llames María E. , Matsuzaki Shin‐Ichiro S. , Nodine Emily R. , Piccolo Maria Cintia , Pierson Don C. , Rimmer Alon , Rudstam Lars G. , Sadro Steven , Swain Hilary M. , Thackeray Stephen J. , Thiery Wim , Verburg Piet , Zohary Tamar , Stockwell Jason D.
Published: April 2021

The intensity and frequency of storms are projected to increase in many regions of the world because of climate change. Storms can alter environmental conditions in many ecosystems. In lakes and reservoirs, storms can reduce epilimnetic temperatures from wind‐induced mixing with colder hypolimnetic waters, direct precipitation to the lake's surface, and watershed runoff. We analyzed 18 long‐term and high‐frequency lake datasets from 11 countries to assess the magnitude of wind‐ vs. rainstorm‐induced changes in epilimnetic temperature. We found small day‐to‐day epilimnetic temperature decreases in response to strong wind and heavy rain during stratified conditions. Day‐to‐day epilimnetic temperature decreased, on average, by 0.28°C during the strongest windstorms (storm mean daily wind speed among lakes: 6.7 ± 2.7 m s−1, 1 SD) and by 0.15°C after the heaviest rainstorms (storm mean daily rainfall: 21.3 ± 9.0 mm). The largest decreases in epilimnetic temperature were observed ≥2 d after sustained strong wind or heavy rain (top 5th percentile of wind and rain events for each lake) in shallow and medium‐depth lakes. The smallest decreases occurred in deep lakes. Epilimnetic temperature change from windstorms, but not rainstorms, was negatively correlated with maximum lake depth. However, even the largest storm‐induced mean epilimnetic temperature decreases were typically <2°C. Day‐to‐day temperature change, in the absence of storms, often exceeded storm‐induced temperature changes. Because storm‐induced temperature changes to lake surface waters were minimal, changes in other limnological variables (e.g., nutrient concentrations or light) from storms may have larger impacts on biological communities than temperature changes.