bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient obstacle detection based on prior estimation network and spatially constrained mixture model for unmanned surface vehicles
Authors: Liu Jingyi , Li Hengyu , Luo Jun , Xie Shaorong , Sun Yu
Published: August 2020

Recently, spatially constrained mixture model has become the mainstream method for the task of vision‐based obstacle detection in unmanned surface vehicles (USVs), and has shown its potential of modeling the semantic structure of the marine environment. However, the expectation maximization (EM) optimization of this model is quite sensitive to initial values and easily falls into a local optimal solution in the presence of significant rolling and pitching in rough seas. In addition, existing methods based on spatially constrained mixture model are susceptible to false positives in the presence of sun glitter. In this paper, a prior estimation network (PEN) is proposed to improve the mixture model, which together enable reliable monocular obstacle detection for USVs. We develop a weakly supervised E‐step to train the PEN for learning the semantic structure of marine images and estimating initial class priors in obstacle detection. To mitigate the influence of poor initial parameters on the convergence of EM optimization, we use the priors estimated by the PEN to calculate the initial parameters of the mixture model and automatically adjust the hyper priors on the semantic components in the mixture model. The output of the PEN is also applied to set the probability values of the outlier component in the mixture model, aiming to reduce false positives caused by sun glitter. Experimental results show that our approach outperforms the current state‐of‐the‐art monocular method by 15% improvement in sea edge estimation and a 3.3% increase in F‐score on the marine obstacle detection data set, as well as 69.5% improvement in sea edge estimation and a 39.2% increase in F‐score on our data set, while running over 40 fps.
Banknotes, bookkeeping barter, and cloth money: Conversions of “special‐purpose money” in the cloth and dammar trade of Sulawesi, Indonesia, 1860–1905
Authors: Schrauwers Albert
Published: August 2020

The trade in cotton cloth and dammar in late nineteenth‐century Sulawesi passed through three distinct exchange spheres mediated by barter. The highland end users transformed European‐made cloth into a special‐purpose money like the classic case of brass rods among the Tiv. In contrast to Bohannon's treatment of the Tiv, I set the highlanders' use of cloth money in the same analytic frame as the money of European trading companies and their local intermediaries. Each of these three exchange spheres utilized a different special‐purpose money, each of which performed only a few of the functions of general‐purpose money. European traders utilized “financial paper” as a “means of exchange” with European partners. They utilized a system of “bookkeeping barter” to manage the trade with their local intermediaries, where money now served as a “standard of value” and “unit of account.” Lastly, the highlanders utilized the cotton cloth they bartered for dammar as a “means of payment” but not as a “means of exchange.” By examining the terms by which money was socially embedded in all three exchange spheres, we gain an alternate perspective on the creation of many of the classic “social currencies” emerging out of early international trade networks.
Bad news for announcers, good news for rivals: Are rivals fully seizing transition‐period opportunities following announcers' top management turnovers?
Authors: Burchard Cord H. , Proelss Juliane , Schäffer Utz , Schweizer Denis
Published: August 2020

Research summary

This study analyzes whether and how the disruption of top management turnovers can affect not only turnover firms but also their intra‐industry rivals. It thus adds to the literature on both leader life cycles and competitive dynamics. Using a U.S. sample of 857 CEO turnovers, we find a period of relative stagnation for announcing companies following top management turnovers. We also find that intra‐industry rivals can use this period to their advantage. Semi‐structured interviews with seasoned CEOs, CFOs, and a board member from large publicly listed firms, as well as an extensive news search, support this notion. Intra‐industry rivals gain a competitive advantage that can result in positive abnormal stock returns and accounting performance. The intra‐industry outperformance is greater for forced turnovers.

Managerial summary

The departure of a company's CEO, forced or not, is usually a disruptive event for a company, as the successor must adapt to the new environment before undertaking any major strategic changes. Rivals can seize an opportunity during the transition period of the announcing company because they remain fully operational. They can thus actively exploit the relative inability of turnover companies to react by, for example, launching sales initiatives or increasing M&A activity. This interpretation is supported by internal and external evidence. Investors on average also recognize this situation, and stock prices react accordingly.
Revisit on holographic complexity in two-dimensional gravity
Authors: Cai Rong-Gen , He Song , Wang Shao-Jiang , Zhang Yu-Xuan
Published: August 2020

Abstract

We revisit the late-time growth rate of various holographic complexity conjectures for neutral and charged AdS black holes with single or multiple horizons in two dimensional (2D) gravity like Jackiw-Teitelboim (JT) gravity and JT-like gravity. For complexity-action conjecture, we propose an alternative resolution to the vanishing growth rate at late-time for general 2D neutral black hole with multiple horizons as found in the previous studies for JT gravity. For complexity-volume conjectures, we obtain the generic forms of late-time growth rates in the context of extremal volume and Wheeler-DeWitt volume by appropriately accounting for the black hole thermodynamics in 2D gravity.
Spin-one dark matter and gamma ray signals from the galactic center
Authors: Hernández-Arellano H. , Napsuciale M. , Rodríguez S.
Published: August 2020

Abstract

In this work we study the possibility that the gamma ray excess (GRE) at the Milky Way galactic center come from the annihilation of dark matter with a (1, 0) ⊕ (0, 1) space-time structure (spin-one dark matter, SODM). We calculate the production of prompt photons from initial state radiation, internal bremsstrahlung, final state radiation including the emission from the decay products of the μ, τ or hadronization of quarks. Next we study the delayed photon emission from the inverse Compton scattering (ICS) of electrons (produced directly or in the prompt decay of μ, τ leptons or in the hadronization of quarks produced in the annihilation of SODM) with the cosmic microwave background or starlight. All these mechanisms yield significant contributions only for Higgs resonant exchange, i.e. for M ≈ MH /2, and the results depend on the Higgs scalar coupling to SODM, gs. The dominant mechanism at the GRE bump is the prompt photon production in the hadronization of b quarks produced in $$ \overline{D}D\to \overline{b}b $$

D
¯

D
→

b
¯

b
, whereas the delayed photon emission from the ICS of electrons coming from the hadronization of b quarks produced in the same reaction dominates at low energies (ω < 0.3 GeV ) and prompt photons from c and τ , as well as from internal bremsstrahlung, yield competitive contributions at the end point of the spectrum (ω ≥ 30 GeV ). Taking into account all these contributions, our results for photons produced in the annihilation of SODM are in good agreement with the GRE data for gs ∈ [0.98, 1.01] × 10−3 and M ∈ [62.470, 62.505] GeV . We study the consistency of the corresponding results for the dark matter relic density, the spin-independent dark matter-nucleon cross-section σp and the cross section for the annihilation of dark matter into $$ \overline{b}b $$

b
¯

b
, τ+τ−, μ+μ− and γγ, taking into account the Higgs resonance effects, finding consistent results in all cases.
Evolution of entanglement wedge cross section following a global quench
Authors: Velni Komeil Babaei , Mozaffar M. Reza Mohammadi , Vahidinia M.H.
Published: August 2020

Abstract

We study the evolution of entanglement wedge cross section (EWCS) in the Vaidya geometry describing a thin shell of null matter collapsing into the AdS vacuum to form a black brane. In the holographic context, it is proposed that this quantity is dual to different information measures including entanglement of purification, reflected entropy, odd entropy and logarithmic negativity. In 2 + 1 dimensions, we present a combination of numerical and analytic results on the evolution and scaling of EWCS for strip shaped boundary subregions after a thermal quench. In the limit of large subregions, we find that the time evolution of EWCS is characterized by three different scaling regimes: an early time quadratic growth, an intermediate linear growth and a late time saturation. Further, in 3 + 1 dimensions, we examine the scaling behavior by considering thermal and electromagnetic quenches. In the case of a thermal quench, our numerical analysis supply results similar to observations made for the lower dimension. On the other hand, for electromagnetic quenches at zero temperature, an interesting feature is a departure from the linear behavior of the evolution to logarithmic growth.
6d $$ \mathcal{N} $$ = (1, 0) anomalies on S1 and F-theory implications
Authors: Corvilain Pierre
Published: August 2020

Abstract

We show that the pure gauge anomalies of 6d $$ \mathcal{N} $$
N
= (1, 0) theories compactified on a circle are captured by field-dependent Chern-Simons terms appearing at one-loop in the 5d effective theories. These terms vanish if and only if anomalies are canceled. In order to obtain this result, it is crucial to integrate out the massive Kaluza-Klein modes in a way that preserves 6d Lorentz invariance; the often-used zeta-function regularization is not sufficient. Since such field-dependent Chern-Simons terms do not arise in the reduction of M-theory on a threefold, six-dimensional F-theory compactifications are automatically anomaly free, whenever the M/F-duality can be used. A perfect match is then found between the 5d $$ \mathcal{N} $$
N
= 1 prepotentials of the classical M-theory reduction and one-loop circle compactification of an anomaly free theory. Finally, from this potential, we read off the quantum corrections to the gauge coupling functions.
Holographic QFTs on S2×S2, spontaneous symmetry breaking and Efimov saddle points
Authors: Kiritsis Elias , Nitti Francesco , Préau Edwan
Published: August 2020

Abstract

Holographic CFTs and holographic RG flows on space-time manifolds which are d-dimensional products of spheres are investigated. On the gravity side, this corresponds to Einstein-dilaton gravity on an asymptotically AdSd+1 geometry, foliated by a product of spheres. We focus on holographic theories on S2× S2, we show that the only regular five-dimensional bulk geometries have an IR endpoint where one of the sphere shrinks to zero size, while the other remains finite. In the Z2-symmetric limit, where the two spheres have the same UV radii, we show the existence of a infinite discrete set of regular solutions, satisfying an Efimov-like discrete scaling. The Z2-symmetric solution in which both spheres shrink to zero at the endpoint is singular, whereas the solution with lowest free energy is regular and breaks Z2 symmetry spontaneously. We explain this phenomenon analytically by identifying an unstable mode in the bulk around the would-be Z2-symmetric solution. The space of theories have two branches that are connected by a conifold transition in the bulk, which is regular and correspond to a quantum first order transition. Our results also imply that AdS5 does not admit a regular slicing by S2× S2.
Role of Conventional Dynamic Myelography for Detection of High-Flow Cerebrospinal Fluid Leaks
Authors: Piechowiak Eike I. , Pospieszny Katarzyna , Haeni Levin , Jesse Christopher M. , Peschi Giovanni , Mosimann Pascal J. , Kaesmacher Johannes , Mordasini Pasquale , Raabe Andreas , Ulrich Christian T. , Beck Jürgen , Gralla Jan , Dobrocky Tomas
Published: August 2020

Background

Spinal imaging is essential to identify and localize cerebrospinal fluid (CSF) leaks in spontaneous intracranial hypotension (SIH) patients when targeted treatment is necessary.

Purpose

Provide an in-depth presentation of the conventional dynamic myelography (CDM) technique for localizing spinal CSF leaks in SIH patients.

Material and Methods

Consecutive SIH patients with a CSF leak confirmed on CDM and postmyelography computed tomography (CT) investigated at our institution between 2013 and 2019 were retrospectively analyzed. Intraoperative reports were reviewed to confirm the accuracy of CDM.

Results

In total, 62 patients (mean age 45 years) were included; 48 with a ventral dural tear, 12 with a meningeal diverticulum, and in 2 patients positive for spinal longitudinal extradural CSF collection the site remained unclear. The leak was identified during the first and the second CDM in 43 and 17 patients, respectively. The use of CDM correctly identified the site of the CSF leak in all but one patient undergoing surgical closure (45/46, 98%). The mean fluoroscopy time was 7.8 min (range 1.8–14.4 min) with a radiation dose for a single examination of 310 mGy (range 28–1237 mGy).

Conclusion

The CDM procedure has a high accuracy for spinal CSF leak localization including dural tears and spinal nerve diverticula. It is the technique with the highest temporal resolution, is robust to breathing artifacts, allows great flexibility regarding patient positioning, compares favorably to other dynamic examinations with respect to the radiation dose and does not require general anesthesia. For CSF venous fistulas, however, other dynamic examinations, such as digital subtraction myelography, seem more appropriate.
Expanding and validating the biomarkers for mitochondrial diseases
Authors: Maresca Alessandra , Del Dotto Valentina , Romagnoli Martina , La Morgia Chiara , Di Vito Lidia , Capristo Mariantonietta , Valentino Maria Lucia , Carelli Valerio ,   the ER-MITO Study Group
Published: August 2020

Mitochondrial diseases are highly heterogeneous metabolic disorders caused by genetic alterations in the mitochondrial DNA (mtDNA) or in the nuclear genome. In this study, we investigated a panel of blood biomarkers in a cohort of 123 mitochondrial patients, with prominent neurological and muscular manifestations. These biomarkers included creatine, fibroblast growth factor 21 (FGF21) and growth/differentiation factor 15 (GDF-15), and the novel cell free circulating-mtDNA (ccf-mtDNA). All biomarkers were significantly increased in the patient group. After stratification by the specific phenotypes, ccf-mtDNA was significantly increased in the Mitochondrial Encephalomyopathy Lactic Acidosis Stroke-like episodes syndrome (MELAS) group, and FGF21 and GDF-15 were significantly elevated in patients with MELAS and Myoclonic Epilepsy Ragged Red Fibers syndrome. On the contrary, in our cohort, creatine was not associated to a specific clinical phenotype. Longitudinal assessment in four MELAS patients showed increased levels of ccf-mtDNA in relation to acute events (stroke-like episodes/status epilepticus) or progression of neurodegeneration. Our results confirm the association of FGF21 and GDF-15 with mitochondrial translation defects due to tRNA mutations. Most notably, the novel ccf-mtDNA was strongly associated with MELAS and may be used for monitoring the disease course or to evaluate the efficacy of therapies, especially in the acute phase.

Key messages

• FGF21/GDF15 efficiently identifies mitochondrial diseases due to mutations in tRNA genes.

• The novel ccf-mtDNA is associated with MELAS and increases during acute events.

• Creatine only discriminates severe mitochondrial patients.

• FGF21, GDF-15, and ccf-mtDNA are possibly useful for monitoring therapy efficacy.
Estimation of autocovariance matrices for high dimensional linear processes
Authors: Furmańczyk Konrad
Published: August 2020

In this paper under some mild restrictions upper bounds on the rate of convergence for estimators of $$p\times p$$

p
×
p

autocovariance and precision matrices for high dimensional linear processes are given. We show that these estimators are consistent in the operator norm in the sub-Gaussian case when $$p={\mathcal {O}}\left( n^{\gamma /2}\right) $$

p
=
O

n

γ
/
2

for some $$\gamma >1$$

γ
>
1

, and in the general case when $$ p^{2/\beta }(n^{-1} \log p)^{1/2}\rightarrow 0$$

p

2
/
β

(

n

-
1

log
p
)

1
/
2

→
0

for some $$\beta >2$$

β
>
2

as $$ p=p(n)\rightarrow \infty $$

p
=
p
(
n
)
→
∞

and the sample size $$n\rightarrow \infty $$

n
→
∞

. In particular our results hold for multivariate AR processes. We compare our results with those previously obtained in the literature for independent and dependent data. We also present non-asymptotic bounds for the error probability of these estimators.
Tert-butyldimethylsilyl chitosan synthesis and characterization by analytical ultracentrifugation, for archaeological wood conservation
Authors: Wakefield Jennifer M. K. , Braovac Susan , Kutzke Hartmut , Stockman Robert A. , Harding Stephen E.
Published: August 2020

The Oseberg ship is one of the most important archaeological testimonies of the Vikings. After excavation in 1904, the wooden gravegoods were conserved using alum salts. This resulted in extreme degradation of a number of the objects a hundred years later through acid depolymerisation of cellulose and lignin. The fragile condition of the artefacts requires a reconsolidation which has to be done avoiding water as solvent. We synthesized tert-butyldimethylsilyl (TBDMS) chitosan which is soluble in a 50:50 solution of ethyl acetate and toluene. Measurement of its molecular weight, to anticipate its penetration, provided a challenge as the density difference of the polymer and solvent was too small to provide adequate solute redistribution under a centrifugal field, so a two-stage process was implemented (i) determination of the weight-average molar mass of the aqueous soluble activated precursor, chitosan mesylate, Mw,mc using sedimentation equilibrium with the SEDFIT-MSTAR algorithm, and determination of the degree of polymerisation DP; (ii) measurement of the average degree of substitution DSTBDMS of the TBDMS group on each chitosan monosaccharide monomer unit using NMR, to augment the Mw,mc value to give the molar mass of the TBDMS-chitosan. For the preparation, we find Mw = 9.8 kg·mol−1, which is within the acceptable limit for penetration and consolidation of degraded wood. Future work will test this on archaeological wood from different sources.
Differentiating rheumatoid and psoriatic arthritis: a systematic analysis of high-resolution magnetic resonance imaging features—preliminary findings
Authors: Abrar Daniel B. , Schleich Christoph , Brinks Ralph , Goertz Christine , Schneider Matthias , Nebelung Sven , Sewerin Philipp
Published: August 2020

Background

Because of overlapping phenotypical presentations, the diagnostic differentiation of rheumatoid arthritis (RA) and psoriatic arthritis (PsA) remains challenging. Thus, this study aimed to examine the diagnostic value of distinct imaging features obtained by high-resolution 3-T MRI for the diagnostic differentiation.

Materials and methods

Seventeen patients with PsA and 28 patients with RA were imaged at high resolution using 3-T MRI scanners and a dedicated 16-channel hand coil. All images were analyzed according to the outcome measures in rheumatology clinical trials’ (OMERACT) RAMRIS (Rheumatoid Arthritis Magnetic Resonance Imaging Score) and PsAMRIS (Psoriatic Arthritis Magnetic Resonance Imaging Score) for the presence and intensity of synovitis, flexor tenosynovitis, bone edema, bone erosion, periarticular inflammation, bone proliferation, and joint space narrowing. Next, odds ratios (OR) were calculated to determine the strength of the associations between these imaging features, demographic characteristics, and the outcome RA vs. PsA.

Results

PsA could be differentiated from RA by extracapsular inflammatory changes (PsAMRIS sub-score “periarticular inflammation”), with low odds for the presence of RA (OR of 0.06, p < 0.01) at all metacarpophalangeal (MCP) joints. A prediction model informed by the items that were strongest associated with the presence of RA or PsA demonstrated excellent differentiating capability with an area under the curve of 98.1%.

Conclusion

High-resolution imaging is beneficial for the identification of relevant imaging features that may assist the clinical differentiation of inflammatory conditions of the hand. At the MCP level, extracapsular inflammatory changes were strongly associated with PsA and may consequently allow the imaging differentiation of PsA and RA.
Prediction of tumour grade and survival outcome using pre-treatment PET- and MRI-derived imaging features in patients with resectable pancreatic ductal adenocarcinoma
Authors: Dunet Vincent , Halkic Nermin , Sempoux Christine , Demartines Nicolas , Montemurro Michael , Prior John O. , Schmidt Sabine
Published: August 2020

Objectives

To perform a correlation analysis between histopathology and imaging in patients with previously untreated pancreatic ductal adenocarcinoma (PDAC) and to determine the prognostic values of clinical, histological, and imaging parameters regarding overall survival (OS), disease-specific survival (DSS), and progression-free survival (PFS).

Methods

This single-centre study prospectively included 61 patients (32 males; median age, 68.0 years [IQR, 63.0–75.0 years]) with histologically confirmed PDAC and following surgical resection who preoperatively underwent 18F-FDG PET/CT and DW-MRI. On whole lesions, we measured, using a 42% SUVmax threshold volume of interest (VOI), the following quantitative parameters: mean and maximum standardised uptake values (SUVmean and SUVmax), total lesion glycolysis (TLG), metabolic tumour volume (MTV), mean and minimum apparent diffusion coefficient (ADCmean and ADCmin), diffusion total volume (DTV), and MTV/ADCmin ratio. Spearman’s correlation analysis was performed to assess relationships between these markers and histopathological findings from surgical specimens (stage; grade; resection quality; and vascular, perineural, and lymphatic invasion). Kaplan-Meier and Cox hazard ratio methods were used to evaluate the impacts of imaging parameters on OS (n = 41), DSS (n = 36), and PFS (n = 41).

Results

Inverse correlations between ADCmin and SUVmax (rho = − 0.34; p = 0.0071), and between SUVmean and ADCmean (rho = − 0.29; p = 0.026) were identified. ADCmin was inversely correlated with tumour grade (rho = − 0.40; p = 0.0015). MTV was an independent predictive factor for OS and DSS, while DTV was an independent predictive factor for PFS.

Conclusion

In previously untreated PDAC, ADC and SUV values are correlated. Combining PET-MRI metrics may help predict PDAC grade and patients’ survival.

Key Points

• Minimum apparent diffusion coefficient derived from DW-MRI inversely correlates with tumour grade in pancreatic ductal adenocarcinoma.

• In pancreatic ductal adenocarcinoma, metabolic tumour volume has been confirmed as a predictive factor for patients’ overall survival and disease-specific survival.

• Combining PET and MRI metrics may help predict grade and patients’ survival in pancreatic ductal adenocarcinoma.
Reiseimpfungen bei rheumatischen Erkrankungen
Authors: Welzel T. , Wörner A. , Heininger U.
Published: August 2020

Kinder und Erwachsene mit rheumatischen Erkrankungen (RE) haben nicht nur durch ihre Grunderkrankung, sondern auch durch die vielfach notwendige immunsuppressive Therapie (IT) ein erhöhtes Risiko, an bestimmten Infektionen zu erkranken. Durch die IT hat sich die Lebensqualität bei vielen Patienten mit RE verbessert, sodass ihr internationales Reiseverhalten dem gesunder Reisenden ähnelt. Eine Untersuchung deutet an, dass Patienten mit Immunsuppression oftmals unzureichend auf Reisen vorbereitet sind und ihr Impfschutz schlechter als bei Immungesunden ist. Da auch während und nach Reisen das Erkrankungsrisiko für allgemeine und reisespezifische Infektionen bei Patienten mit Immunsuppression erhöht ist, sind reisemedizinische Beratungen bei Patienten mit RE wichtig. Hier können ein Reiserücktritt oder Reisemodifikationen und spezifischer Schutz inklusive Reiseimpfungen besprochen werden. Zu den gängigen Indikationsimpfungen bei Reisen zählen Impfungen gegen Hepatitis A, Typhus, Tollwut, Meningokokken, FSME (Frühsommer-Meningoenzephalitis), saisonale Influenza, Japanische Enzephalitis, Cholera, Poliomyelitis und Gelbfieber. Bei Patienten mit RE ergibt sich die Impfindikation dabei aus der möglichen Exposition gegenüber impfpräventablen Infektionen, dem individuellen Reiseverhalten, der Schwere der möglichen Infektion unter Abwägung der Risiken, die mit der Reiseimpfung assoziiert sind. Dafür müssen auch der allgemeine Gesundheitszustand, die Aktivität und Schwere der RE und der Grad der IT beachtet werden. Allgemein gilt für Patienten mit RE und IT, dass auch bei Reiseimpfungen Lebendimpfstoffe kontraindiziert sind, während Totimpfstoffe verabreicht werden können. Da eine reduzierte Impfantwort möglich ist, können Antikörpermessungen nach der Impfserie und spezifische Impfschemata oder zusätzliche Booster bei Patienten mit RE indiziert sein.
SARS-CoV-2 & Rheuma
Authors: Leipe J. , Hoyer B. F. , Iking-Konert C. , Schulze-Koops H. , Specker C. , Krüger K.
Published: August 2020

Die Empfehlungen des Deutschen Gesellschaft für Rheumatologie(DGRh)-Updates – welches die zu Beginn der COVID-19-Pandemie erstellte Hilfestellung zum Management von Patienten mit entzündlich rheumatischen Erkrankungen angesichts der Bedrohung durch SARS-CoV‑2 aktualisiert und erweitert – stimmen in vielen Punkten mit den Handlungsempfehlungen der amerikanischen (ACR) und europäischen Fachgesellschaften (EULAR) überein, unterscheiden sich aber auch in einigen Punkten. In diesem Artikel sollen daher Kernempfehlungen des DGRh-Updates zu den Themen Prävention von SARS-CoV-2/COVID-19, Risikoeinschätzung bei ERE sowie der Umgang mit antirheumatischen Therapien im Kontext bzw. im Vergleich zu den ACR- und EULAR-Empfehlungen diskutiert und eine Übersicht zur Risikobeurteilung einzelner antirheumatischer Medikamente gegeben werden.
Stationary distribution and cover time of sparse directed configuration models
Authors: Caputo Pietro , Quattropani Matteo
Published: August 2020

We consider sparse digraphs generated by the configuration model with given in-degree and out-degree sequences. We establish that with high probability the cover time is linear up to a poly-logarithmic correction. For a large class of degree sequences we determine the exponent $$\gamma \ge 1$$

γ
≥
1

of the logarithm and show that the cover time grows as $$n\log ^{\gamma }(n)$$

n

log
γ

(
n
)

, where n is the number of vertices. The results are obtained by analysing the extremal values of the stationary distribution of the digraph. In particular, we show that the stationary distribution $$\pi $$
π
is uniform up to a poly-logarithmic factor, and that for a large class of degree sequences the minimal values of $$\pi $$
π
have the form $$\frac{1}{n}\log ^{1-\gamma }(n)$$

1
n

log

1
-
γ

(
n
)

, while the maximal values of $$\pi $$
π
behave as $$\frac{1}{n}\log ^{1-\kappa }(n)$$

1
n

log

1
-
κ

(
n
)

for some other exponent $$\kappa \in [0,1]$$

κ
∈
[
0
,
1
]

. In passing, we prove tight bounds on the diameter of the digraphs and show that the latter coincides with the typical distance between two vertices.
Evaluation of a remote-controlled laparoscopic camera holder for basic laparoscopic skills acquisition: a randomized controlled trial
Authors: Amin Mohammad S. A. , Aydin Abdullatif , Abbud Nurhan , Van Cleynenbreugel Ben , Veneziano Domenico , Somani Bhaskar , Gözen Ali Serdar , Redorta Juan Palou , Khan M. Shamim , Dasgupta Prokar , Makanjuoala Jonathan , Ahmed Kamran
Published: August 2020

Background

Unsteady camera movement and poor visualization contribute to a difficult learning curve for laparoscopic surgery. Remote-controlled camera holders (RCHs) aim to mitigate these factors and may be used to overcome barriers to learning. Our aim was to evaluate performance benefits to laparoscopic skill acquisition in novices using a RCH.

Methods

Novices were randomized into groups using a human camera assistant (HCA) or the FreeHand v1.0 RCH and trained in the (E-BLUS) curriculum. After completing training, a surgical workload questionnaire (SURG-TLX) was issued to participants.

Results

Forty volunteers naïve in laparoscopic skill were randomized into control and intervention groups (n = 20) with intention-to-treat analysis. Each participant received up to 10 training sessions using the E-BLUS curriculum. Competency was reached in the peg transfer task in 5.5 and 7.6 sessions for the ACH and HCA groups, respectively (P = 0.015), and 3.6 and 6.8 sessions for the laparoscopic suturing task (P = 0.0004). No significance differences were achieved in the circle cutting (P = 0.18) or needle guidance tasks (P = 0.32). The RCH group experienced significantly lower workload (P = 0.014) due to lower levels of distraction (P = 0.047).

Conclusions

Remote-controlled camera holders have demonstrated the potential to significantly benefit intra-operative performance and surgical experience where camera movement is minimal. Future high-quality studies are needed to evaluate RCHs in clinical practice.

Trial registration

ISRCTN 83733979
Ein Kupfergusskuchen mit hohem Antimongehalt aus Velem/Westungarn
Authors: Haubner Roland , Strobl Susanne , Thurner Manuela , Herdits Hannes
Published: August 2020

In der archäologischen Sammlung des Burgenländischen Landesmuseums befindet sich ein urnenfelderzeitlicher Gusskuchen aus der Burg von Velem, einer prähistorischen befestigten Höhensiedlung auf einer Rückfallkuppe des Bernstein-Rechnitzer Fensters (BLM Inv. Nr. A154201). Velem liegt heute in Ungarn und ist seit Beginn des vorigen Jahrhunderts für seine zahlreichen metallurgischen Funde bekannt. Aufgrund des Fundortes bestand bereits die Vermutung, dass er Antimon enthalten könnte. Mittels RFA Analyse wurde ein Sb-Gehalt von 10 Gew.% nachgewiesen. Zusätzlich sind 4,5 Gew.% As, je 1,2 Gew.% S und Ag im Gusskuchen enthalten.

Die Verteilung unterschiedlicher Gefüge im Gusskuchen ist sehr inhomogen. In großen Bereichen liegt dendritisch erstarrtes Cu vor. In den interdendritischen Bereichen findet man unterschiedliche Phasengemische der Elemente Cu-Sb-As‑S. Ein auffälliger Streifen aus Cu2S, der sich quer durch den Gusskuchen zieht, legt die Vermutung nahe, dass dieser Gusskuchen aus geschmolzener Arsenbronze durch Zumischen von Antimonit (Sb2S3) entstanden ist. In der geologischen Formation „Rechnitzer Fenster“ sind mehrere Fundstellen von Antimonit bekannt, die Quelle der verwendeten Arsenbronze ist jedoch unbekannt.
Physical activity and low back pain in children and adolescents: a systematic review
Authors: Kędra Agnieszka , Plandowska Magdalena , Kędra Przemysław , Czaprowski Dariusz
Published: August 2020

Introduction

Due to a high prevalence of low back pain (LBP) among children and adolescents, it is significant to seek effective prevention and therapeutic procedures. One idea for the programmes is a potential relation between the occurrence of LBP and the level of physical activity. The aim of this review was to analyse the current knowledge regarding the association between physical activity and LBP among children and adolescents.

Methods

Publications were retrieved by searching the following databases: PubMed, The Cochrane library, Web of Science, Medline and SportDiscus with Full Text (EBSCO). The search strategy included keywords related to physical activity and LBP. The studies included were assessed for methodological quality. PRISMA guidelines were followed for the systematic review.

Results

The total sample size of the nine included studies consisted of 75,233 subjects, with an age range of 9–19 years. All the studies were assessed to be of high quality. One cohort study and five cross-sectional studies found the association between physical activity and LBP in children and adolescents. The remaining studies found no relationship between physical activity and LBP. These findings showed that both extremes of activity levels (i.e. being very low and very high physically active) are associated with LBP.

Conclusion

There is moderate evidence for the association between physical activity and LBP in children and adolescents. The results highlight the need for continued research. It seems that for clear evaluation of the analysed association the prospective cohort studies should be conducted.
Detection of endogenous lipids in chicken feathers distinct from preen gland constituents
Authors: Zeisler-Diehl Viktoria , Al-Khutabi Eshrak Ali Ali , Kirfel Gregor , Schreiber Lukas , van Echten-Deckert Gerhild , Herzog Volker
Published: August 2020

Bird feather lipids are usually attributed to the oily secretion product of the uropygial (preen) gland. We have observed, however, that feathers exhibit a strong reaction with osmium tetroxide (OsO4), even after treatment with detergents. This leads us to postulate the existence of endogenous feather lipids distinct from preen gland lipids. In order to substantiate our hypothesis, we investigated down feathers from a 1-day-old chicken as their uropgygial gland is not functionally active. The results confirmed the osmiophilic reaction, which was concentrated in the center of barbs and strongly reduced after lipid extraction. In these lipid extracts, we identified using thin layer chromatography, cholesterol, various ceramides, glycolipids, phospholipids, and fatty acids, which closely resembled the lipid composition of the water barrier in the chicken-cornified epidermal envelope. This composition is clearly distinct from chicken uropygeal gland secretion (UGS) known to consist of fatty alcohols as part of aliphatic monoester waxes and of free, predominantly saturated, fatty acids. A filter assay showed a strong reactivity between OsO4 and the fatty acids C18:1 and C18:2 and with feather lipid extracts, but not with UGS. These observations were confirmed by gas chromatography detecting unsaturated fatty acids including C18:1 and C18:2 as well as cholesterol exclusively in chicken feathers. Our results indicate that (1) endogenous lipids are detectable in chicken feathers and distinct from UGS and (2) in analogy to the morphogenesis of the cornified envelope of chicken feather lipids that may have derived from cellular feather-precursors, apparently enduring the specific cell death during developmental feather cornification.
A characterization of supersmoothness of multivariate splines
Authors: Floater Michael S. , Hu Kaibo
Published: August 2020

We consider spline functions over simplicial meshes in$\mathbb {R}^{n}$ℝn. We assume that the spline pieces join together with some finite order of smoothness but the pieces themselves are infinitely smooth. Such splines can have extra orders of smoothness at a vertex, a property known assupersmoothness, which plays a role in the construction of multivariate splines and in the finite element method. In this paper, we characterize supersmoothness in terms of the degeneracy of spaces of polynomial splines over the cell of simplices sharing the vertex, and use it to determine the maximal order of supersmoothness of various cell configurations.
Teachers’ skills to integrate technology in education: Two path models explaining instructional and application software use
Authors: Dogan Selcuk , Dogan Nihan Agacli , Celik Ismail
Published: August 2020

The purpose of this study was to examine the effect of technology support, teachers’ confidence in using technology, their beliefs about using technology, and their perceived skills on the use of instructional and application software. The data we used were from 1335 K-12 teachers involved in the Technology Uses and Perceptions Survey (TUPS) study. Teachers were located in 40 different institutions across the state of Florida. According to the findings of this study, the most significant factor in the instructional and application software use of teachers was found as perceived technology skills. Therefore, professional development for perceived skills or technology competencies of teachers might contribute to increasing the instructional or application software use of teachers. In terms of confidence and comfort using technology, they both had direct and positive effects on instructional and application software. Also, the total effect of support from technology specialists for instructional software use is more than application software use. As evidenced by the models developed in this research, teachers’ perceived technology skills for instructional and application software use directly and positively affected their beliefs on usefulness. Our effort to provide more emphasis on the combined effect of a collective set of factors to explain teacher use of technology leads us to address the gaps in the literature on technology use (i.e., the effect of demographic factors and technology availability).
Three contextual dimensions of information on social media: lessons learned from the COVID-19 infodemic
Authors: Marin Lavinia
Published: August 2020

The COVID-19 pandemic has been accompanied on social media by an explosion of information disorders such as inaccurate, misleading and irrelevant information. Countermeasures adopted thus far to curb these informational disorders have had limited success because these did not account for the diversity of informational contexts on social media, focusing instead almost exclusively on curating the factual content of user’s posts. However, content-focused measures do not address the primary causes of the infodemic itself, namely the user’s need to post content as a way of making sense of the situation and for gathering reactions of consensus from friends. This paper describes three types of informational context—weak epistemic, strong normative and strong emotional—which have not yet been taken into account by current measures to curb down the informational disorders. I show how these contexts are related to the infodemic and I propose measures for dealing with them for future global crisis situations.
Intergenerational Transmission of Party Affiliation Within Political Families
Authors: Aggeborn Linuz , Nyman Pär
Published: August 2020

We investigate the intergenerational transmission of political-party affiliation within families with at least two politicians. We use Swedish registry data that covers all nominated politicians for the years 1982 to 2014, as well as their family ties. First, we demonstrate there is a strong link between individuals and their parents concerning party affiliation. We also find that this intergenerational transmission persists over generations and across siblings. Our second aim is to investigate the mechanisms behind this result, which we do by first discussing two hypotheses: the one concerns a socialization pathway, the other a materialistic one. We then bring these hypotheses to the data, and we find that the socialization pathway matters more for intergenerational transmission.
Gastrojejunal Anastomotic Technique. Does It Matter? Weight Loss and Weight Regain 5 Years After Laparoscopic Roux-en-Y Gastric Bypass
Authors: Fehervari Matyas , Alyaqout Khaled , Lairy Ali , Khwaja Haris , Bonanomi Gianluca , Efthimiou Evangelos
Published: August 2020

Purpose

The gastrojejunostomy during laparoscopic Roux-en-Y gastric bypass (LRYGB) can be constructed by hand sewn (HSA), linear (LSA) and circular (CSA) stapler technique. They are all considered safe; however, it is not known which the best technique is. Short-term follow-up suggest no difference in weight loss or weight regain between them. However, there is no information on these parameters in the long term. Theatre time and cost are other important factors defining the best way to form gastrojejunostomy.

Materials and Methods

In a prospective longitudinal cohort study consecutive patients following primary LRYGB were recruited to a bariatric database in a tertiary care centre. Anastomotic technique, diameter, the length of operations and associated costs, weight loss and weight regain were recorded. Patients were followed up for 5 years.

Results

A total of 385 patients with an initial body mass index of 47.1 kg/m2 (35–68) were enrolled to this study. This decreased to 33.3 kg/m2 (21–54 kg/m2) after 5 years. There was no difference in %TWL after 3 years, P = 0.296, or 5 years, P = 0.187, between the techniques. The number of patients with weight regain was not different after 3 years, P = 0.224, or 5 years, P = 0.795. All techniques had similar operative time. CSA has a higher material cost. Early anastomotic stricture was more common following HSA; however, the difference was not significant.

Conclusion

Mid-term weight loss and weight regain are not related to anastomotic technique, and there is no difference in operative time associated to them. Circular stapler technique has a higher material cost due to the additional stapler.
Addressing Pitfalls in Phase-Amplitude Coupling Analysis with an Extended Modulation Index Toolbox
Authors: Jurkiewicz Gabriela J. , Hunt Mark J. , Żygierewicz Jarosław
Published: August 2020

Phase-amplitude coupling (PAC) is proposed to play an essential role in coordinating the processing of information on local and global scales. In recent years, the methods able to reveal trustworthy PAC has gained considerable interest. However, the intrinsic features of some signals can lead to the identification of spurious or waveform-dependent coupling. This prompted us to develop an easily accessible tool that could be used to differentiate spurious from authentic PAC. Here, we propose a new tool for more reliable detection of PAC named the Extended Modulation Index () based on the classical Modulation Index measure of coupling. is suitable both for continuous and epoched data and allows estimation of the statistical significance of each pair of frequencies for phase and for amplitude in the whole comodulogram in the framework of extreme value statistics. We compared with the reference PAC measures—direct PAC estimator (a modification of Mean Vector Length) and standard Modulation Index. All three methods were tested using computer-simulated data and actual local field potential recordings from freely moving rats. All methods exhibited similar properties in terms of sensitivity and specificity of PAC detection. proved to be more selective in the dimension of frequency for phase. One of the novelty’s offered by is a heuristic algorithm for classification of PAC as Reliable or Ambiguous. It relies on analysis of the relation between the spectral properties of the signal and the detected coupling. Moreover, generates visualizations that support further evaluation of the coupling properties. It also introduces the concept of the polar phase-histogram to study phase relations of coupled slow and fast oscillations. We discuss the extent to which addresses the known problems of interpreting PAC. The Matlab® toolbox implementing framework, and the two reference PAC estimators is freely available as EEGLAB plugin at https://github.com/GabrielaJurkiewicz/ePAC.
Graded and pan-neural disease phenotypes of Rett Syndrome linked with dosage of functional MeCP2
Authors: Chen Xiaoying , Han Xu , Blanchi Bruno , Guan Wuqiang , Ge Weihong , Yu Yong-Chun , Sun Yi E.
Published: August 2020

Rett syndrome (RTT) is a progressive neurodevelopmental disorder, mainly caused by mutations in MeCP2 and currently with no cure. We report here that neurons from R106W MeCP2 RTT human iPSCs as well as human embryonic stem cells after MeCP2 knockdown exhibit consistent and long-lasting impairment in maturation as indicated by impaired action potentials and passive membrane properties as well as reduced soma size and spine density. Moreover, RTT-inherent defects in neuronal maturation could be pan-neuronal and occurred in neurons with both dorsal and ventral forebrain features. Knockdown of MeCP2 led to more severe neuronal deficits as compared to RTT iPSC-derived neurons, which appeared to retain partial function. Strikingly, consistent deficits in nuclear size, dendritic complexity and circuitry-dependent spontaneous postsynaptic currents could only be observed in MeCP2 knockdown neurons but not RTT iPSC-derived neurons. Both neuron-intrinsic and circuitry-dependent deficits of MeCP2-deficient neurons could be fully or partially rescued by re-expression of wild type or T158M MeCP2, strengthening the dosage dependency of MeCP2 on disease phenotypes and also the partial function of the mutant. Our findings thus reveal stable neuronal maturation deficits and unexpectedly, graded sensitivities of neuron-inherent and neural transmission phenotypes towards the extent of MeCP2 deficiency, which is informative for future therapeutic development.
Characterizing the fecal bacteria and archaea community of heifers and lactating cows through 16S rRNA next-generation sequencing
Authors: Cendron Filippo , Niero Giovanni , Carlino Gabriele , Penasa Mauro , Cassandro Martino
Published: August 2020

The aim of this study was to describe the fecal bacteria and archaea composition of Holstein-Friesian and Simmental heifers and lactating cows, using 16S rRNA gene sequencing. Bacteria and archaea communities were characterized and compared between heifers and cows of the same breed. Two breeds from different farms were considered, just to speculate about the conservation of the microbiome differences between cows and heifers that undergo different management conditions. The two breeds were from two different herds. Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria were the most abundant phyla in all experimental groups. Alpha- and beta-diversity metrics showed significant differences between heifers and cows within the same breed, supported by principal coordinate analysis. The analysis of Holstein-Friesian fecal microbiome composition revealed 3 different bacteria families, 2 genera, and 2 species that differed between heifers and cows; on the other hand, Simmental heifers and cows differed only for one bacteria family, one archaeal genus, and one bacteria species. Results of the present study suggest that fecal communities of heifers and cows are different, and that fecal microbiome is maintained across experimental groups.