bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust compartmental model fitting in direct emission tomography reconstruction
Authors: Szirmay-Kalos László , Kacsó Ágota , Magdics Milán , Tóth Balázs 
Published: February 2021

AbstractDynamic tomography reconstructs a time activity curve (TAC) for every voxel assuming that the algebraic form of the function is known a priori. The algebraic form derived from the analysis of compartmental models depends nonlinearly on the nonnegative parameters to be determined. Direct methods apply fitting in every iteration step. Because of the iterative nature of the maximum likelihood–expectation maximization (ML–EM) reconstruction, the fitting result of the previous step can serve as a good starting point in the current step; thus, after the first iteration we have a guess that is not far from the solution, which allows the use of gradient-based local optimization methods. However, finding good initial guesses for the first ML–EM iteration is a critical problem since gradient-based local optimization algorithms do not guarantee convergence to the global optimum if they are started at an inappropriate location. This paper examines the robust solution of the fitting problem both in the initial phase and during the ML–EM iteration. This solution is implemented on GPUs and is built into the 4D reconstruction module of the TeraTomo software.
Dynamic and thermodynamic impacts of climate change on organized convection in Alaska
Authors: Poujol Basile , Prien Andreas F. , Molina Maria J. , Muller Caroline 
Published: February 2021

AbstractConvective storms can cause economic damage and harm to humans by producing flash floods, lightning and severe weather. While organized convection is well studied in the tropics and mid-latitudes, few studies have focused on the physics and climate change impacts of pan-Arctic convective systems. Using a convection-permitting model we showed in a predecessor study that organized convective storm frequency might triple by the end of the century in Alaska assuming a high emission scenario. The present study assesses the reasons for this rapid increase in organized convection by investigating dynamic and thermodynamic changes within future storms and their environments, in light of canonical existing theories for mid-latitude and tropical deep convection. In a future climate, more moisture originates from Arctic marine basins increasing relative humidity over Alaska due to the loss of sea ice, which is in sharp contrast to lower-latitude land regions that are expected to become drier. This increase in relative humidity favors the onset of organized convection through more unstable thermodynamic environments, increased low-level buoyancy, and weaker downdrafts. Our confidence in these results is increased by showing that these changes can be analytically derived from basic physical laws. This suggests that organized thunderstorms might become more frequent in other pan-Arctic continental regions highlighting the uniqueness and vulnerability of these regions to climate change.
Detection of circulating genetically abnormal cells using 4-color fluorescence in situ hybridization for the early detection of lung cancer
Authors: Feng Mingxiang , Ye Xin , Chen Baishen , Zhang Juncheng , Lin Miao , Zhou Haining , Huang Meng , Chen Yanci , Zhu Yunhe , Xiao Botao , Huang Chuoji , Katz Ruth L. , Bai Chunxue 
Published: February 2021

Abstract
Purpose
Available biomarkers lack sensitivity for an early lung cancer. Circulating genetically abnormal cells (CACs) occur early in tumorigenesis. To determine the diagnostic value of CACs in blood detected by 4-color fluorescence in situ hybridization (FISH) for lung cancer.

Methods
This was a prospective study of patients with pulmonary nodules ≤ 30 mm detected between 10/2019 and 01/2020 at four tertiary hospitals in China. All patients underwent a pathological examination of lung nodules found by imaging and were grouped as malignant and benign. CACs were detected by 4-color FISH. Patients were divided into the training and validation cohorts. Receiver operating characteristics analysis was used to analyze the diagnosis value of CACs.

Results
A total of 205 participants were enrolled. Using a cut-off value of ≥ 3, blood CACs achieved areas under the curve (AUCs) of 0.887, 0.823, and 0.823 for lung cancer in the training and validation cohorts, and all patients, respectively. CACs had high diagnostic values across all tumor sizes and imaging lesion types. CACs were decreased after surgery (median, 4 vs. 1, P < 0.001) in the validation set. The CAC status between blood and tissues was highly consistent (kappa = 0.909, P < 0.001). The AUC of CAC (0.823) was higher than that of CEA (0.478), SCC (0.516), NSE (0.506), ProGRP (0.519), and CYFRA21-1 (0.535) (all P < 0.001).

Conclusion
CACs might have a high value for the early diagnosis of lung cancer. These findings might need to be validated in future studies. Evidence suggested homology in genetic aberrations between the CACs and the tumor cells.
Human TERT promoter mutations as a prognostic biomarker in glioma
Authors: Powter Branka , Jeffreys Sarah A. , Sareen Heena , Cooper Adam , Brungs Daniel , Po Joseph , Roberts Tara , Koh Eng-Siew , Scott Kieran F. , Sajinovic Mila , Vessey Joey Y. , de Souza Paul , Becker Therese M. 
Published: February 2021

AbstractThe TERT promoter (pTERT) mutations, C228T and C250T, play a significant role in malignant transformation by telomerase activation, oncogenesis and immortalisation of cells. C228T and C250T are emerging as important biomarkers in many cancers including glioblastoma multiforme (GBM), where the prevalence of these mutations is as high as 80%. Additionally, the rs2853669 single nucleotide polymorphism (SNP) may cooperate with these pTERT mutations in modulating progression and overall survival in GBM. Using liquid biopsies, pTERT mutations, C228T and C250T, and other clinically relevant biomarkers can be easily detected with high precision and sensitivity, facilitating longitudinal analysis throughout therapy and aid in cancer patient management.In this review, we explore the potential for pTERT mutation analysis, via liquid biopsy, for its potential use in personalised cancer therapy. We evaluate the relationship between pTERT mutations and other biomarkers as well as their potential clinical utility in early detection, prognostication, monitoring of cancer progress, with the main focus being on brain cancer.
Using ultrasound-targeted microbubble destruction to enhance radiotherapy of glioblastoma
Authors: Peng Chanjuan , Wu Yong , Yang Yang , Li Ningning , Chen Xi , Gu Linhui , Xu Dong , Yang Chen 
Published: February 2021

Abstract
Objective
To investigate the efficacy and mechanism of ultrasound-targeted microbubble destruction (UTMD) combined with radiotherapy (XRT) on glioblastoma.

Methods
The enhanced radiosensitization by UTMD was assessed through colony formation and cell apoptosis in Human glioblastoma cells (U87MG). Subcutaneous transplantation tumors in 24 nude mice implanted with U87MG cells were randomly assigned to 4 different treatment groups (Control, UTMD, XRT, and UTMD + XRT) based on tumor sizes (100–300 mm3). Tumor growth was observed for 10 days after treatment, and then histopathology stains (HE, CD34, and γH2AX) were applied to the tumor samples. A TUNEL staining experiment was applied to detect the apoptosis rate of mice tumor samples. Meanwhile, tissue proteins were extracted from animal specimens, and the expressions of dsDNA break repair-related proteins from animal specimens were examined by the western blot.

Results
When the radiotherapy dose was 4 Gy, the colony formation rate of U87MG cells in the UTMD + XRT group was 32 ± 8%, lower than the XRT group (54 ± 14%, p < 0.01). The early apoptotic rate of the UTMD + XRT group was 21.1 ± 3% at 48 h, higher than that of the XRT group (15.2 ± 4%). The tumor growth curve indicated that the tumor growth was inhibited in the UTMD + XRT group compared with other groups during 10 days of observation. In TUNEL experiment, the apoptotic cells of the UTMD + XRT group were higher than that of the XRT group (p < 0.05). The UTMD + XRT group had the lowest MVD value, but was not significantly different from other groups (p > 0.05). In addition, γH2AX increased due to the addition of UTMD to radiotherapy compared to XRT in immunohistochemistry (p < 0.05).

Conclusions
Our study clearly demonstrated the enhanced destructive effect of UTMD combined with 4 Gy radiotherapy on glioblastoma. This could be partly achieved by the increased ability of DNA damage of tumor cells.
High honeybee abundances reduce wild bee abundances on flowers in the city of Munich
Authors: Renner Susanne S. , Graf Marie Sophie , Hentschel Zoe , Krause Helen , Fleischmann Andreas 
Published: February 2021

AbstractThe increase in managed honeybees (Apis mellifera) in many European cities has unknown effects on the densities of wild bees through competition. To investigate this, we monitored honeybees and non-honeybees from 01 April to 31 July 2019 and 2020 at 29 species of plants representing diverse taxonomic and floral-functional types in a large urban garden in the city of Munich in which the same plant species were cultivated in both years. No bee hives were present in the focal garden, and all bee hives in the adjacent area were closely monitored by interviewing the relevant bee keepers in both 2019 and 2020. Honeybee numbers were similar in April of both years, but increased from May to July 2020 compared to 2019. The higher densities correlated with a significant increase in shifts from wild bee to honeybee visits in May/June/July, while visitor spectra in April 2019 and 2020 remained the same. Most of the species that experienced a shift to honeybee visits in 2020 were visited mostly or exclusively for their nectar. There were no shifts towards increased wild bee visits in any species. These results from a flower-rich garden have implications for the discussion of whether urban bee keeping might negatively impact wild bees. We found clear support that high honeybee densities result in exploitative competition at numerous types of flowers.
An online review of informational sources for advanced or high-risk cutaneous squamous cell carcinoma
Authors: Starkings Rachel , Shilling Valerie , Fallowfield Lesley 
Published: February 2021

Abstract
Objective
Cutaneous squamous cell carcinoma (cSCC) is one of the most prevalent non-melanoma skin cancers worldwide. While usually treatable, patients with high-risk or advanced disease have few treatment options and limited resources available. This review assesses what online information resources are available to patients and their families about either high-risk or advanced cSCC.

Methods
Searches were run, via Google, using 8 terms such as ‘advanced cutaneous squamous cell carcinoma patient information’. Advertisements were removed and the first 3 pages/30 results from each search were screened for duplicates and then against eligibility criteria. Websites needed to have been updated within the past 5 years, be freely accessible, designed specifically for patients and refer to the advanced disease or high-risk setting. Remaining results were assessed using the DISCERN tool.

Results
Of the final 240 results, 121 were duplicates and 104 were ineligible. The remaining 15 sources were predominantly aimed at American audiences, used variable terminology and revealed differing treatment pathways. Only 3 sites were deemed as ‘high’-quality information sources.

Conclusion
There is a lack of accessible online information on high-risk or advanced cSCC for patients. What is available is often too scientific or clinical and lacks clarity about the disease and treatment options.

Practice Implications
Further work is needed to improve the integrity and accessibility of online sources and to signpost patients to the most reliable information. This should include elements of patient led research, clinical education and information development.
Mechanisms and applications of vibration energy harvesting in solid rocket motors
Authors: Goel Chirag , Srinivas G. 
Published: February 2021

AbstractEnergy harvesting has become a fascinating topic of research. As the world moves towards reducing its dependency on fossil fuels, new and innovative techniques of energy harvesting have been tested and developed. The use of piezoelectric materials to harvest the ambient vibrations from the surroundings is one method that has seen a dramatic rise in use for power harvesting. Remote sensors can be powered by these piezoelectric materials and could potentially act as a continuous source of energy. In space vehicles, energy is generated using solar panels which are bulky, heavy and expensive. Instead piezoelectric harvesters can be used to generate power and are much lighter, compact and relatively cheap when produced in bulk. This paper presents a theoretical study on energy harvesting from structural vibration caused by combustion instability of a solid rocket motor through the motor burnout. Vibration data of tested solid rocket motor was taken as a reference and was inputted as the boundary condition. The 3-D model of the harvester system was designed on Fusion360 and the simulation was performed on COMSOL. Finally, improvements needed in the system to enhance practicality were discussed.
Permeability Evolution During Shear Zone Initiation in Low-Porosity Rocks
Authors: Kluge Christian , Blöcher Guido , Barnhoorn Auke , Schmittbuhl Jean , Bruhn David 
Published: February 2021

AbstractUsing an innovative experimental set-up (Punch-Through Shear test), we initiated a shear zone (microfault) in Flechtingen sandstone and Odenwald granite under in situ reservoir conditions while monitoring permeability and fracture dilation evolution. The shear zone, which has a cylindrical geometry, is produced by a self-designed piston assembly that punches down the inner part of the sample. Permeability and fracture dilation were measured for the entire duration of the experiment. After the shear zone generation, the imposed shear displacement was increased to 1.2 mm and pore pressure changes of $$\pm 5$$

±
5

or $$\pm 10$$

±
10

MPa were applied cyclically to simulate injection and production scenarios. Thin sections and image analysis tools were used to identify microstructural features of the shear zone. The geometry of the shear zone is shown to follow a self-affine scaling invariance, similar to the fracture surface roughness. The permeability evolution related to the onset of the fracture zone is different for both rocks: almost no enhancement for the Flechtingen sandstone and an increase of more than 2 orders of magnitude for the Odenwald granite. Further shear displacement resulted in a slight increase in permeability. A fault compaction is observed after shear relaxation which is associated to a permeability decrease by a factor more than 3. Permeability changes during pressure cycling are reversible when varying the effective pressure. The difference in permeability enhancement between the sandstone and the granite is related to the larger width of the shear zones.
Path planning and collision avoidance for autonomous surface vehicles II: a comparative study of algorithms
Authors: Vagale Anete , Bye Robin T. , Oucheikh Rachid , Osen Ottar L. , Fossen Thor I. 
Published: February 2021

AbstractArtificial intelligence is an enabling technology for autonomous surface vehicles, with methods such as evolutionary algorithms, artificial potential fields, fast marching methods, and many others becoming increasingly popular for solving problems such as path planning and collision avoidance. However, there currently is no unified way to evaluate the performance of different algorithms, for example with regard to safety or risk. This paper is a step in that direction and offers a comparative study of current state-of-the art path planning and collision avoidance algorithms for autonomous surface vehicles. Across 45 selected papers, we compare important performance properties of the proposed algorithms related to the vessel and the environment it is operating in. We also analyse how safety is incorporated, and what components constitute the objective function in these algorithms. Finally, we focus on comparing advantages and limitations of the 45 analysed papers. A key finding is the need for a unified platform for evaluating and comparing the performance of algorithms under a large set of possible real-world scenarios.
Outer approximation for global optimization of mixed-integer quadratic bilevel problems
Authors: Kleinert Thomas , Grimm Veronika , Schmidt Martin 
Published: February 2021

AbstractBilevel optimization problems have received a lot of attention in the last years and decades. Besides numerous theoretical developments there also evolved novel solution algorithms for mixed-integer linear bilevel problems and the most recent algorithms use branch-and-cut techniques from mixed-integer programming that are especially tailored for the bilevel context. In this paper, we consider MIQP-QP bilevel problems, i.e., models with a mixed-integer convex-quadratic upper level and a continuous convex-quadratic lower level. This setting allows for a strong-duality-based transformation of the lower level which yields, in general, an equivalent nonconvex single-level reformulation of the original bilevel problem. Under reasonable assumptions, we can derive both a multi- and a single-tree outer-approximation-based cutting-plane algorithm. We show finite termination and correctness of both methods and present extensive numerical results that illustrate the applicability of the approaches. It turns out that the proposed methods are capable of solving bilevel instances with several thousand variables and constraints and significantly outperform classical solution approaches.
Rates of superlinear convergence for classical quasi-Newton methods
Authors: Rodomanov Anton , Nesterov Yurii 
Published: February 2021

AbstractWe study the local convergence of classical quasi-Newton methods for nonlinear optimization. Although it was well established a long time ago that asymptotically these methods converge superlinearly, the corresponding rates of convergence still remain unknown. In this paper, we address this problem. We obtain first explicit non-asymptotic rates of superlinear convergence for the standard quasi-Newton methods, which are based on the updating formulas from the convex Broyden class. In particular, for the well-known DFP and BFGS methods, we obtain the rates of the form $$(\frac{n L^2}{\mu ^2 k})^{k/2}$$

(

n

L
2

μ
2

k

)

k
/
2

and $$(\frac{n L}{\mu k})^{k/2}$$

(

nL

μ
k

)

k
/
2

respectively, where k is the iteration counter, n is the dimension of the problem, $$\mu $$
μ
is the strong convexity parameter, and L is the Lipschitz constant of the gradient.
The sub-fossil red coral of Sciacca (Sicily Channel, Mediterranean Sea): colony size and age estimates
Authors: Bavestrello Giorgio , Bo Marzia , Calcagnile Lucio , Canessa Martina , D’Elia Marisa , Quarta Gianluca , Spagnoli Federico , Cattaneo-Vietti Riccardo 
Published: February 2021

AbstractThe Mediterranean red coral, Corallium rubrum (L.), has been a valuable economic resource for more than 2000 years. The Sicily Channel and surrounding areas are one of the most famous red coral fishing grounds of the whole region, hosting the deepest ever found living colonies and large sub-fossil red coral deposits; the so-called Sciacca banks are a unique location in the whole Mediterranean Sea. In this paper, a morphometric description of this sub-fossil population is presented for the first time from studies of colonies in the collection of several coral factories from Torre del Greco (Naples), with radiocarbon age estimations and growth rate evaluations. From the results of this study, after several thousand years Sciacca red coral colonies maintained the organic matrix structure with evident annual discontinuities, allowing estimations of the annual growth rate (about 0.3 mm/year) and the average population age (about 33.5 years). These resulting data are similar to the values determined for deep-dwelling living red coral populations. The radiocarbon dating evidenced a range of ages, from 8300 to 40 years before 1950 CE, mostly falling between 2700 and 3900 YBP, suggesting that colonies accumulated over a wide span of time. In view of the tectonically active nature of the area, several catastrophic events affected these ancient populations, maintaining them in a persistent state of early-stage, structurally similar to the those in current over-exploited areas.
Edge detection with trigonometric polynomial shearlets
Authors: Schober Kevin , Prestin Jürgen , Stasyuk Serhii A. 
Published: February 2021

AbstractIn this paper, we show that certain trigonometric polynomial shearlets which are special cases of directional de la Vallée Poussin-type wavelets are able to detect step discontinuities along boundary curves of periodic characteristic functions. Motivated by recent results for discrete shearlets in two dimensions, we provide lower and upper estimates for the magnitude of the corresponding inner products. In the proof, we use localization properties of trigonometric polynomial shearlets in the time and frequency domain and, among other things, bounds for certain Fresnel integrals. Moreover, we give numerical examples which underline the theoretical results.
A three-term recurrence relation for accurate evaluation of transition probabilities of the simple birth-and-death process
Authors: Pessia Alberto , Tang Jing 
Published: February 2021

AbstractThe simple (linear) birth-and-death process is a widely used stochastic model for describing the dynamics of a population. When the process is observed discretely over time, despite the large amount of literature on the subject, little is known about formal estimator properties. Here we will show that its application to observed data is further complicated by the fact that numerical evaluation of the well-known transition probability is an ill-conditioned problem. To overcome this difficulty we will rewrite the transition probability in terms of a Gaussian hypergeometric function and subsequently obtain a three-term recurrence relation for its accurate evaluation. We will also study the properties of the hypergeometric function as a solution to the three-term recurrence relation. We will then provide formulas for the gradient and Hessian of the log-likelihood function and conclude the article by applying our methods for numerically computing maximum likelihood estimates in both simulated and real dataset.
Pathways to Lasting Cross-Sector Social Collaboration: A Configurational Study
Authors: Weber Christiana , Haugh Helen , Göbel Markus , Leonardy Hannes 
Published: February 2021

AbstractCross-sector social collaborations are increasingly recognised as valuable inter-organizational arrangements that seek to combine the commercial capabilities of private sector companies with the deep knowledge of social and environmental issues enrooted in social sector organizations. In this paper we empirically examine the configurations of conditions that lead to lasting cross-sector social collaboration. Situating our enquiry in Schütz’s theory of life-worlds and the reciprocity literature, we employ fuzzy-set qualitative comparative analysis (fsQCA) to analyse data gathered from 60 partners in 30 cross-sector social collaborations. We find two distinct types of configurational pathways leading to lasting cross-sector social collaboration which we labelreciprocal economic exchangebased on direct reciprocity, andreciprocal social exchangebased on generalised reciprocity. The pathways vary in terms of the delivery of expected and unexpected resources and benefits. We introduce the concept ofdouble relationalityto explain the interdependence of structure and action in lasting cross sector social collaboration.