bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural polyphenols as sirtuin 6 modulators
Authors: Rahnasto-Rilla Minna , Tyni Jonna , Huovinen Marjo , Jarho Elina , Kulikowicz Tomasz , Ravichandran Sarangan , A. Bohr Vilhelm , Ferrucci Luigi , Lahtela-Kakkonen Maija , Moaddel Ruin
Published: March 2018

Flavonoids are polyphenolic secondary metabolites synthesized by plants and fungus with various pharmacological effects. Due to their plethora of biological activities, they have been studied extensively in drug development. They have been shown to modulate the activity of a NAD+-dependent histone deacetylase, SIRT6. Because SIRT6 has been implicated in longevity, metabolism, DNA-repair, and inflammatory response reduction, it is an interesting target in inflammatory and metabolic diseases as well as in cancer. Here we show, that flavonoids can alter SIRT6 activity in a structure dependent manner. Catechin derivatives with galloyl moiety displayed significant inhibition potency against SIRT6 at 10 µM concentration. The most potent SIRT6 activator, cyanidin, belonged to anthocyanidins, and produced a 55-fold increase in SIRT6 activity compared to the 3–10 fold increase for the others. Cyanidin also significantly increased SIRT6 expression in Caco-2 cells. Results from the docking studies indicated possible binding sites for the inhibitors and activators. Inhibitors likely bind in a manner that could disturb NAD+ binding. The putative activator binding site was found next to a loop near the acetylated peptide substrate binding site. In some cases, the activators changed the conformation of this loop suggesting that it may play a role in SIRT6 activation.
Inter-niche and inter-individual variation in gut microbial community assessment using stool, rectal swab, and mucosal samples
Authors: Jones Roshonda B. , Zhu Xiangzhu , Moan Emili , Murff Harvey J. , Ness Reid M. , Seidner Douglas L. , Sun Shan , Yu Chang , Dai Qi , Fodor Anthony A. , Azcarate-Peril M. Andrea , Shrubsole Martha J.
Published: March 2018

The purpose of this study is to evaluate similarities and differences in gut bacterial measurements and stability in the microbial communities of three different types of samples that could be used to assess different niches of the gut microbiome: rectal swab, stool, and normal rectal mucosa samples. In swab-stool comparisons, there were substantial taxa differences with some taxa varying largely by sample type (e.g. Thermaceae), inter-individual subject variation (e.g. Desulfovibrionaceae), or by both sample type and participant (e.g. Enterobacteriaceae). Comparing all three sample types with whole-genome metagenome shotgun sequencing, swab samples were much closer to stool samples than mucosa samples although all KEGG functional Level 1 and Level 2 pathways were significantly different across all sample types (e.g. transcription and environmental adaptation). However, the individual signature of participants was also observed and was largely stable between two time points. Thus, we found that while the distribution of some taxa was associated with these different sampling techniques, other taxa largely reflected individual differences in the microbial community that were insensitive to sampling technique. There is substantial variability in the assessment of the gut microbial community according to the type of sample.
Polarity-inverted lateral overgrowth and selective wet-etching and regrowth (PILOSWER) of GaN
Authors: Jang Dongsoo , Jue Miyeon , Kim Donghoi , Kim Hwa Seob , Lee Hyunkyu , Kim Chinkyo
Published: March 2018

On an SiO2-patterned c-plane sapphire substrate, GaN domains were grown with their polarity controlled in accordance with the pattern. While N-polar GaN was grown on hexagonally arranged circular openings, Ga-polar GaN was laterally overgrown on mask regions due to polarity inversion occurring at the boundary of the circular openings. After etching of N-polar GaN on the circular openings by H3PO4, this template was coated with 40-nm Si by sputtering and was slightly etched by KOH. After slight etching, a thin layer of Si left on the circular openings of sapphire,but not on GaN, was oxidized during thermal annealing and served as a dielectric mask during subsequent regrowth. Thus, the subsequent growth of GaN was made only on the existing Ga-polar GaN domains, not on the circular openings of the sapphire substrate. Transmission electron microscopy analysis revealed no sign of threading dislocations in this film. This approach may help fabricating an unholed and merged GaN film physically attached to but epitaxially separated from the SiO2-patterned sapphire.
Variation in avian egg shape and nest structure is explained by climatic conditions
Authors: Englert Duursma Daisy , Gallagher Rachael V. , Price J. Jordan , Griffith Simon C.
Published: March 2018

Why are avian eggs ovoid, while the eggs of most other vertebrates are symmetrical? The interaction between an egg and its environment likely drives selection that will shape eggs across evolutionary time. For example, eggs incubated in hot, arid regions face acute exposure to harsh climatic conditions relative to those in temperate zones, and this exposure will differ across nest types, with eggs in open nests being more exposed to direct solar radiation than those in enclosed nests. We examined the idea that the geographical distribution of both egg shapes and nest types should reflect selective pressures of key environmental parameters, such as ambient temperature and the drying capacity of air. We took a comparative approach, using 310 passerine species from Australia, many of which are found in some of the most extreme climates on earth. We found that, across the continent, egg elongation decreases and the proportion of species with domed nests with roofs increases in hotter and drier areas with sparse plant canopies. Eggs are most spherical in open nests in the hottest environments, and most elongate in domed nests in wetter, shadier environments. Our findings suggest that climatic conditions played a key role in the evolution of passerine egg shape.
A combined method for DNA analysis and radiocarbon dating from a single sample
Authors: Korlević Petra , Talamo Sahra , Meyer Matthias
Published: March 2018

Current protocols for ancient DNA and radiocarbon analysis of ancient bones and teeth call for multiple destructive samplings of a given specimen, thereby increasing the extent of undesirable damage to precious archaeological material. Here we present a method that makes it possible to obtain both ancient DNA sequences and radiocarbon dates from the same sample material. This is achieved by releasing DNA from the bone matrix through incubation with either EDTA or phosphate buffer prior to complete demineralization and collagen extraction utilizing the acid-base-acid-gelatinization and ultrafiltration procedure established in most radiocarbon dating laboratories. Using a set of 12 bones of different ages and preservation conditions we demonstrate that on average 89% of the DNA can be released from sample powder with minimal, or 38% without any, detectable collagen loss. We also detect no skews in radiocarbon dates compared to untreated samples. Given the different material demands for radiocarbon dating (500 mg of bone/dentine) and DNA analysis (10–100 mg), combined DNA and collagen extraction not only streamlines the sampling process but also drastically increases the amount of DNA that can be recovered from limited sample material.
Down-regulation of GADD45A enhances chemosensitivity in melanoma
Authors: Liu Jia , Jiang Guoqiang , Mao Ping , Zhang Jing , Zhang Lin , Liu Likun , Wang Jia , Owusu Lawrence , Ren Baoyin , Tang Yawei , Li Weiling
Published: March 2018

Melanoma is a malignant skin cancer with considerable drug resistance. Increased expression of DNA repair genes have been reported in melanoma, and this contributes to chemotherapy resistance. GADD45A is involved in DNA repair, cell cycle arrest and apoptosis in response to physiologic or environmental stresses. In this study, we investigated the role of GADD45A in chemotherapy response. Firstly, the mRNA expression of profiled DNA repair genes in cisplatin-treated melanoma cells was detected by RT2 profilerTM PCR array. We found the expression of GADD45A upregulated in a dose- and time- dependent manner. In addition, suppression of GADD45A sensitized melanoma cells to cisplatin and enhanced cisplatin-induced DNA damage. Flow cytometry revealed that downregulating GADD45A released cells from cisplatin-induced G2/M arrest and increased apoptosis. By using a MEK inhibitor, GADD45A was shown to be regulated by MAPK-ERK pathway following cisplatin treatment. Thus, the induction of GADD45A might play important roles in chemotherapy response in human melanoma cancer and could serve as a novel molecular target for melanoma therapy.
On the insulator-to-metal transition in titanium-implanted silicon
Authors: Liu Fang , Wang Mao , Berencén Yonder , Prucnal Slawomir , Engler Martin , Hübner René , Yuan Ye , Heller René , Böttger Roman , Rebohle Lars , Skorupa Wolfgang , Helm Manfred , Zhou Shengqiang
Published: March 2018

Hyperdoped silicon with deep level impurities has attracted much research interest due to its promising optical and electrical properties. In this work, single crystalline silicon supersaturated with titanium is fabricated by ion implantation followed by both pulsed laser melting and flash lamp annealing. The decrease of sheet resistance with increasing Ti concentration is attributed to a surface morphology effect due to the formation of cellular breakdown at the surface and the percolation conduction at high Ti concentration is responsible for the metallic-like conductivity. The insulator-to-metal transition does not happen. However, the doping effect of Ti incorporation at low concentration is not excluded, which might be responsible for the sub-bandgap optical absorption reported in literature.
Image-Guided Focused-Ultrasound CNS Molecular Delivery: An Implementation via Dynamic Contrast-Enhanced Magnetic-Resonance Imaging
Authors: Chai Wen-Yen , Chu Po-Chun , Tsai Chih-Hung , Lin Chung-Yin , Yang Hung-Wei , Lai Hsin-Yi , Liu Hao-Li
Published: March 2018

Focused ultrasound (FUS) exposure with microbubbles can transiently open the blood-brain barrier (BBB) to deliver therapeutic molecules into CNS tissues. However, delivered molecular distribution/concentration at the target need to be controlled. Dynamic Contrast-Enhanced Magnetic-Resonance Imaging (DCE-MRI) is a well-established protocol for monitoring the pharmacokinetic/pharmacodynamic behavior of FUS-BBB opening. This study investigates the feasibility of using DCE-MRI to estimate molecular CNS penetration under various exposure conditions and molecule sizes. In the 1st stage, a relationship among the imaging index Ktrans, exposure level and molecular size was calibrated and established. In the 2nd stage, various exposure levels and distinct molecules were applied to evaluate the estimated molecular concentration discrepancy with the quantified ones. High correlation (r2 = 0.9684) between Ktrans and transcranial mechanical index (MI) implies Ktrans can serve as an in vivo imaging index to mirror FUS-BBB opening scale. When testing various molecules with the size ranging 1–149 kDa, an overall correlation of r2 = 0.9915 between quantified and predicted concentrations was reached, suggesting the established model can provide reasonably accurate estimation. Our work demonstrates the feasibility of estimating molecular penetration through FUS-BBB opening via DCE-MRI and may facilitate development of FUS-induced BBB opening in brain drug delivery.
N-Acetyl-Aspartate in the dorsolateral prefrontal cortex in men with schizophrenia and auditory verbal hallucinations: A 1.5 T Magnetic Resonance Spectroscopy Study
Authors: Psomiades Marion , Mondino Marine , Fonteneau Clara , Bation Remy , Haesebaert Frederic , Suaud-Chagny Marie-Françoise , Brunelin Jerome
Published: March 2018

Auditory verbal hallucinations (AVH) in patients with schizophrenia are linked to abnormalities within a large cerebral network including frontal and temporal regions. Whilst abnormalities of frontal speech production and temporal speech perception regions have been extensively studied, alterations of the dorsolateral prefrontal cortex (DLPFC), a region critically involved in the pathophysiology of schizophrenia, have rarely been studied in relation to AVH. Using 1.5 T proton magnetic resonance spectroscopy, this study examined the relationship between right and left DLPFCs N-AcetylAspartate (NAA) levels and the severity of AVH in patients with schizophrenia. Twenty-seven male patients with schizophrenia were enrolled in this study, 15 presented daily treatment-resistant AVH (AVH+) and 12 reported no AVH (no-AVH). AVH+ patients displayed higher NAA levels in the right DLPFC than no-AVH patients (p = 0.033). In AVH+ patients, NAA levels were higher in the right DLPFC than in the left (p = 0.024). No difference between the right and left DLPFC was observed in no-AVH patients. There was a positive correlation between NAA levels in the right DLPFC and the severity of AVH (r = 0.404, p = 0.037). Despite limited by magnetic field strength, these results suggest that AVH may be associated with increased NAA levels in the right DLPFC in schizophrenia.
Correction: Corrigendum: A multi-functional bubble-based microfluidic system
Authors: Khoshmanesh Khashayar , Almansouri Abdullah , Albloushi Hamad , Yi Pyshar , Soffe Rebecca , Kalantar-zadeh Kourosh
Published: March 2018

Scientific Reports 5: Article number: 9942; published online: 23 April 2015; updated: 01 March 2018 The Acknowledgements section in this Article was omitted. The Acknowledgements section should read: “Khashayar Khoshmanesh acknowledges the Australian Research Council for funding under the Discovery Early Career Researcher Award (DECRA) scheme (Project No.
Atomistic investigations on the mechanical properties and fracture mechanisms of indium phosphide nanowires
Authors: Pial Turash Haque , Rakib Tawfiqur , Mojumder Satyajit , Motalab Mohammad , Akanda M. A. Salam
Published: March 2018

Molecular dynamics tensile simulations reveal that the cleavage fracture plane of ZB InP NWs varies with temperature, while the cleavage plane of WZ InP NWs remains fixed at all temperatures.
Molecular logic gates: the past, present and future
Authors: Erbas-Cakmak Sundus , Kolemen Safacan , Sedgwick Adam C. , Gunnlaugsson Thorfinnur , James Tony D. , Yoon Juyoung , Akkaya Engin U.
Published: March 2018

Molecular logic gates, now with more than two decades of collective exploration, are poised for practical applications.
Whole-grain oats (Avena sativaL.) as a carrier of lactic acid bacteria and a supplement rich in angiotensin I-converting enzyme inhibitory peptides through solid-state fermentation
Authors: Wu Han , Rui Xin , Li Wei , Xiao Yu , Zhou Jianzhong , Dong Mingsheng
Published: March 2018

A novel strategy was found to develop whole-grain oats as a probiotic carrier and a nutraceutical supplement targeting hypertension.
In vitro biological properties and predicted DNA–BSA interaction of three new dicyanidoargentate(i)-based complexes: synthesis and characterization
Authors: Karadağ Ahmet , Korkmaz Nesrin , Aydın Ali , Tekin Şaban , Yanar Yusuf , Yerli Yusuf , Korkmaz Şengül Aslan
Published: March 2018

The synthesis, characterization and biological activity of three novel dicyanidoargentate(i)-based complexes are reported. The in vitro results show that these complexes may be potent antiproliferative drug candidates.
Interfacial nano-mixing in a miniaturised platform enables signal enhancement and in situ detection of cancer biomarkers
Authors: Wuethrich Alain , Sina Abu Ali Ibn , Ahmed Mostak , Lin Ting-Yun , Carrascosa Laura G. , Trau Matt
Published: March 2018

Interfacial nanomixing enhances the adsorption of cancer biomarkers and enables in situ electrochemical detection in a multiplexed device.
New activation mechanism for half-sandwich organometallic anticancer complexes
Authors: Banerjee Samya , Soldevila-Barreda Joan J. , Wolny Juliusz A. , Wootton Christopher A. , Habtemariam Abraha , Romero-Canelón Isolda , Chen Feng , Clarkson Guy J. , Prokes Ivan , Song Lijiang , O'Connor Peter B. , Schünemann Volker , Sadler Peter J.
Published: March 2018

Half-sandwich RhIII anticancer complexes with activated Cp* rings not only undergo sequential CH3 H–D exchange, but also react with biological dienes, generating RhI Diels–Alder adducts in aqueous media at ambient temperature.
Selective extraction of semiconducting single-walled carbon nanotubes with a thermoresponsive polymer
Authors: Shimura Eriko , Sugai Toshiki , Kuwahara Shota
Published: March 2018

The extraction of single-walled carbon nanotubes by exploiting the phase transition of poly(N-isopropylacrylamide) was performed to obtain homogenous electronic properties.
Use of stability diagrams to predict catalyst speciation during Fischer Tropsch reduction stage: a mini-review
Authors: Gorimbo Joshua
Published: March 2018

An alternative way of predicting phase evolution of iron-based Fischer Tropsch synthesis catalysts during activation.
Compositional modification of pyrogenic products using CaCO3 and CO2 from the thermolysis of polyvinyl chloride (PVC)
Authors: Lee Taewoo , Oh Jeong-Ik , Baek Kitae , Tsang Yiu Fai , Kim Ki-Hyun , Kwon Eilhann E.
Published: March 2018

In this study, we explored the mechanistic features of CO2 in the thermolysis of PVC to modify the pyrogenic products.
Using Images With Individuals With Aphasia: Current Research and Clinical Trends
Authors: Brown Jessica , Thiessen Amber
Published: March 2018

Purpose

Visuographic supports in the form of images are utilized during assessment and treatment for individuals with aphasia to supplement speech, language, and cognitive losses limiting communication. Clinicians rely on prior experience and intuition to make decisions regarding image-based support design and selection (e.g., augmentative and alternative communication strategies). Researchers have begun to focus on the relationship between the images and the benefits they provide for adults with aphasia.

Method

The aim of this review—resulting from a roundtable discussion at the 2016 Clinical Aphasiology Conference—was to disseminate summaries of current and past researches regarding image use by individuals with aphasia and to highlight areas of need within research and practice.

Results

Review of the literature illuminated 4 major themes: (a) image creation, capture, and sharing; (b) image characteristics; (c) image use across linguistic domains and contexts; and (d) implications for clinical and research practices.

Conclusions

Reviewing current knowledge and practice regarding the use of visual supports for individuals with aphasia is essential to advancing therapeutic practices and providing evidence-based protocols for creating, selecting, and implementing images within augmentative and alternative communication strategies. Several gaps in knowledge were identified as future research needs (e.g., caregiver training and enhanced image feature investigation).
Attentive Reading With Constrained Summarization Adapted to Address Written Discourse in People With Mild Aphasia
Authors: Obermeyer Jessica A. , Edmonds Lisa A.
Published: March 2018

Purpose

The purpose of this study was to examine the preliminary efficacy of Attentive Reading and Constrained Summarization–Written (ARCS-W) in people with mild aphasia. ARCS-W adapts an existing treatment, ARCS (Rogalski & Edmonds, 2008), to address discourse level writing in mild aphasia. ARCS-W focuses on the cognitive and linguistic skills required for discourse production.

Method

This study was a within-subject pre–postdesign. Three people with mild aphasia participated. ARCS-W integrates attentive reading or listening with constrained summarization of discourse level material in spoken and written modalities. Outcomes included macro- (main concepts) and microlinguistic (correct information units, complete utterances) discourse measures, confrontation naming, aphasia severity, and functional communication.

Results

All 3 participants demonstrated some generalization to untrained spoken and written discourse at the word, sentence, and text levels. Reduced aphasia severity and/or increased functional communication and confrontation naming were also observed in some participants.

Conclusions

The findings of this study provide preliminary evidence of the efficacy of ARCS-W to improve spoken and written discourse in mild aphasia. Different generalization patterns suggest different mechanisms of improvement. Further research and replication are required to better understand how ARCS-W can impact discourse abilities.
Analysis of Story Recall in Military Veterans With and Without Mild Traumatic Brain Injury: Preliminary Results
Authors: Gallagher Karen , Azuma Tamiko
Published: March 2018

Purpose

The purpose of this study was to determine whether detailed analysis of story recall performance reveals significant differences between veterans with and without history of mild traumatic brain injury (mTBI).

Method

Twenty-one military veterans participated, with 7 reporting history of mTBI. All participants were administered the Logical Memory I and II subtests from the Wechsler Memory Scale–Fourth Edition (Wechsler, 2009). Responses were scored for total correct ideas (TCI) and total words produced (TWP).

Results

Although the groups did not differ in scaled scores, other measures did reveal significant differences. After a delay, the mTBI group showed a greater drop in TCI relative to the control group. Additionally, the control group showed an increase in TWP when the recall was delayed versus immediate; a pattern not observed for the mTBI group.

Conclusions

The mTBI and control groups did not significantly differ in scaled scores. However, group differences were observed in TCI and TWP. The findings suggest that, relative to the control group, the mTBI group were less successful in retrieving episodic information and eliciting self-cueing. Small sample size limited data interpretation, and larger sample sizes are needed to confirm the findings. The results indicate that veterans with mTBI may present with symptoms persisting beyond the acute state of the injury.
Considerations for the Use of Neuroimaging Technologies for Predicting Recovery of Speech and Language in Aphasia
Authors: Shuster Linda I.
Published: March 2018

Purpose

The number of research articles aimed at identifying neuroimaging biomarkers for predicting recovery from aphasia continues to grow. Although the clinical use of these biomarkers to determine prognosis has been proposed, there has been little discussion of how this would be accomplished. This is an important issue because the best translational science occurs when translation is considered early in the research process. The purpose of this clinical focus article is to present a framework to guide the discussion of how neuroimaging biomarkers for recovery from aphasia could be implemented clinically.

Method

The genomics literature reveals that implementing genetic testing in the real-world poses both opportunities and challenges. There is much similarity between these opportunities and challenges and those related to implementing neuroimaging testing to predict recovery in aphasia. Therefore, the Center for Disease Control's model list of questions aimed at guiding the review of genetic testing has been adapted to guide the discussion of using neuroimaging biomarkers as predictors of recovery in aphasia.

Conclusion

The adapted model list presented here is a first and useful step toward initiating a discussion of how neuroimaging biomarkers of recovery could be employed clinically to provide improved quality of care for individuals with aphasia.
Dual‐resonance‐based wideband antenna for integrated module applications
Authors: Qu Longyue , Piao Haiyan , Qu Yunhao , Kim Hyung‐Hoon , Kim Hyeongdong
Published: March 2018

A wideband module antenna comprised of a small ground radiation antenna in the module and a parasitic radiation loop in the evaluation board is proposed. Unlike conventional ground radiation antennas, the ground radiation antenna in the module works as an exciter to the parasitic radiation loop, which further couples with the evaluation board as a radiator. Thus, a space‐saving antenna is obtained with wide bandwidth and easy tuning. Accordingly, dual resonance can be generated by tuning the resonant frequencies of the ground radiation antenna and the parasitic radiation loop equally. When measured, the antennas have wide bandwidths (2:1 voltage standing wave ratio bandwidth of 270 MHz) and high efficiency (ranging from 44 to 74%).
Subsonic structure and optically thick winds from Wolf–Rayet stars
Authors: Grassitelli L. , Langer N. , Grin N. J. , Mackey J. , Bestenlehner J. M. , Gräfener G.
Published: March 2018

Mass loss by stellar wind is a key agent in the evolution and spectroscopic appearance of massive main sequence and post-main sequence stars. In Wolf–Rayet stars the winds can be so dense and so optically thick that the photosphere appears in the highly supersonic part of the outflow, veiling the underlying subsonic part of the star, and leaving the initial acceleration of the wind inaccessible to observations. Here we investigate the conditions and the structure of the subsonic part of the outflow of Galactic Wolf–Rayet stars, in particular of the WNE subclass; our focus is on the conditions at the sonic point of their winds. We compute 1D hydrodynamic stellar structure models for massive helium stars adopting outer boundaries at the sonic point. We find that the outflows of our models are accelerated to supersonic velocities by the radiative force from opacity bumps either at temperatures of the order of 200 kK by the iron opacity bump or of the order of 50 kK by the helium-II opacity bump. For a given mass-loss rate, the diffusion approximation for radiative energy transport allows us to define the temperature gradient based purely on the local thermodynamic conditions. For a given mass-loss rate, this implies that the conditions in the subsonic part of the outflow are independent from the detailed physical conditions in the supersonic part. Stellar atmosphere calculations can therefore adopt our hydrodynamic models as ab initio input for the subsonic structure. The close proximity to the Eddington limit at the sonic point allows us to construct a sonic HR diagram, relating the sonic point temperature to the luminosity-to-mass ratio and the stellar mass-loss rate, thereby constraining the sonic point conditions, the subsonic structure, and the stellar wind mass-loss rates of WNE stars from observations. The minimum stellar wind mass-loss rate necessary to have the flow accelerated to supersonic velocities by the iron opacity bump is derived. A comparison of the observed parameters of Galactic WNE stars to this minimum mass-loss rate indicates that these stars have their winds launched to supersonic velocities by the radiation pressure arising from the iron opacity bump. Conversely, stellar models which do not show transonic flows from the iron opacity bump form low-density extended envelopes. We derive an analytic criterion for the appearance of envelope inflation and of a density inversion in the outer sub-photospheric layers.
High redshift galaxies in the ALHAMBRA survey
Authors: Viironen K. , López-Sanjuan C. , Hernández-Monteagudo C. , Chaves-Montero J. , Ascaso B. , Bonoli S. , Cristóbal-Hornillos D. , Díaz-García L. A. , Fernández-Soto A. , Márquez I. , Masegosa J. , Pović M. , Varela J. , Cenarro A. J. , Aguerri J. A. L. , Alfaro E. , Aparicio-Villegas T. , Benítez N. , Broadhurst T. , Cabrera-Caño J. , Castander F. J. , Cepa J. , Cerviño M. , González Delgado R. M. , Husillos C. , Infante L. , Martínez V. J. , Moles M. , Molino A. , del Olmo A. , Perea J. , Prada F. , Quintana J. M.
Published: March 2018

Context.Knowing the exact shape of the ultraviolet (UV) luminosity function (LF) of high-redshift galaxies is important to understand the star formation history of the early Universe. However, the uncertainties, especially at the faint and bright ends of the LFs, remain significant.

Aims.In this paper, we study the UV LF of redshiftz =2.5 – 4.5 galaxies in 2.38 deg2of ALHAMBRA data withI≤ 24. Thanks to the large area covered by ALHAMBRA, we particularly constrain the bright end of the LF. We also calculate the cosmic variance and the corresponding bias values for our sample and derive their host dark matter halo masses.

Methods.We have used a novel methodology based on redshift and magnitude probability distribution functions (PDFs). This methodology robustly takes into account the uncertainties due to redshift and magnitude errors, shot noise, and cosmic variance, and models the LF in two dimensions (z,MUV).

Results.We find an excess of bright *M*UVgalaxies as compared to the studies based on broad-band photometric data. However, our results agree well with the LF of the magnitude-selected spectroscopic VVDS data. We measure high bias values,b ~8 – 10, that are compatible with the previous measurements considering the redshifts and magnitudes of our galaxies and further reinforce the real high-redshift nature of our bright galaxies.

Conclusions.We call into question the shape of the LF at its bright end; is it a double power-law as suggested by the recent broad-band photometric studies or rather a brighter Schechter function, as suggested by our multi-filter analysis and the spectroscopic VVDS data.
Reactivity in interstellar ice analogs: role of the structural evolution
Authors: Ghesquière P. , Ivlev A. , Noble J. A. , Theulé P.
Published: March 2018

Context. The synthesis of interstellar complex organic molecules in ice involves several types of reactions between molecules and/or radicals that are usually considered to be diffusion controlled.

Aims. We aim to understand the coupling between diffusion and reactivity in the interstellar ice mantle using a model binary reaction in the diffusion-limited regime.

Methods. We performed isothermal kinetic laboratory experiments on interstellar ice analogs at low temperatures, using the NH3:CO2:H2O model system where reactants NH3 and CO2 have a low reaction barrier and are diluted in a water-dominated ice.

Results. We found that in the diffusion-limited regime, the reaction kinetics is not determined by the intrinsic bulk diffusivity of reactants. Instead, reactions are driven by structural changes evolving in amorphous water ice, such as pore collapse and crystallization. Diffusion of reactants in this case likely occurs along the surface of (tiny) cracks generated by the structural changes.

Conclusions. The reactivity driven by the structural changes breaks the conventional picture of reactant molecules/radicals diffusing in a bulk water ice. This phenomenon is expected to lead to a dramatic increase in production rates of interstellar complex organic molecules in star-forming regions.
Resonant damping of kink oscillations of thin expanding magnetic tubes
Authors: Shukhobodskiy A. A. , Ruderman M. S.
Published: March 2018

We study the resonant damping of kink oscillations of thin expanding magnetic flux tubes. The tube consists of a core region and a thin transitional region at the tube boundary. The resonance occurs in this transitional layer where the oscillation frequency coincides with the local Alfvén frequency. Our investigation is based on the system of equations that we previously derived. This system is not closed because it contains the jumps of the magnetic pressure perturbation and plasma displacement across the transitional layer. We calculate these jumps and thus close the system. We then use it to determine the decrements of oscillation eigenmodes. We introduce the notion of homogeneous stratification. In accordance with this condition the ratio of densities in the tube core and outside the tube does not vary along the tube, while the density in the transitional layer can be factorised and written as a product of two function, one depending on the variable along the tube and the other on the magnetic flux function. Our main result is that, under the condition of homogeneous stratification, the ratio of the decrement to the oscillation frequency is independent of a particular form of the density variation along the tube. This ratio is also the same for all oscillation eigenmodes.
Dynamics of small-sized Cladocera and their algal diet in lake with toxic cyanobacterial water blooms
Authors: Solis Michał , Pawlik-Skowrońska Barbara , Adamczuk Małgorzata , Kalinowska Renata
Published: March 2018

Species composition and quantitative structure of small-sized Cladocera community and their algal diet before, during and after cyanobacterial blooms were studied in highly eutrophic lake. The objective of the study was to investigate, how the mass development of toxin-producing cyanobacteria affect the abundances of small-sized Cladocera and their preferences within consumed algal cells. Cyanobacterial blooms were predominantly constituted by microcystin-producing generaPlanktothrix,Dolichospermum,Microcystis. The concentration of intracellular microcystins in lake water ranged 0.0–23.61 μg dm−3.Bosmina longirostris,B. coregonii,Diaphanosoma brachyurumandDaphnia cucullatawere dominant in Cladocera community. The highest abundances ofB. longirostrisoccurred in periods without cyanobacterial blooms andB. coregoniiduring blooms and after them. The maximum abundances ofD. cucullatawere observed before and after the cyanobacterial blooms, while the abundance ofD. brachyurumwas the highest at the beginning of blooms. Small Bacillariophyceae, small Chlorophyceae and Cryptophyceae were the most abundant among identified algal cells detected in digestive tracts of the Cladocera dominants. Tracts ofD. cucullata,B.longirostrisandB.coregoniicontained the highest number of Bacillariophyceae always before blooms. During cyanobacterial blooms, cells of small Chlorophyceae predominated in tracts ofD.cucullata. After bloom, cells ofCryptomonasspp. were mainly consumed both byD.cucullataand byB.coregonii. Fragments ofDolichospermumspp., besides Bacillariophyceae andCryptomonasspp. cells, were occasionally found in tracts ofD. brachyurum. Our study indicated that blooms constituted by toxin-producing cyanobacteria may influence quantitative and qualitative structure of the small-sized Cladocera community.
A mixed formulation of the Tikhonov regularization and its application to inverse PDE problems
Authors: Bourgeois Laurent , Recoquillay Arnaud
Published: March 2018

This paper is dedicated to a new way of presenting the Tikhonov regularization in the form of a mixed formulation. Such formulation is well adapted to the regularization of linear ill-posed partial differential equations because when it comes to discretization, the mixed formulation enables us to use some standard finite elements. As an application of our theory, we consider an inverse obstacle problem in an acoustic waveguide. In order to solve it we use the so-called “exterior approach”, which couples the mixed formulation of Tikhonov regularization and a level set method. Some 2d numerical experiments show the feasibility of our approach.
Reconstruction of isotropic conductivities from non smooth electric fields
Authors: Briane Marc
Published: March 2018

In this paper we study the isotropic realizability of a given non smooth gradient field ∇u defined in ℝd, namely when one can reconstruct an isotropic conductivity σ > 0 such that σ∇u is divergence free in ℝd. On the one hand, in the case where ∇u is non-vanishing, uniformly continuous in ℝd and Δu is a bounded function in ℝd, we prove the isotropic realizability of ∇u using the associated gradient flow combined with the DiPerna, Lions approach for solving ordinary differential equations in suitable Sobolev spaces. On the other hand, in the case where ∇u is piecewise regular, we prove roughly speaking that the isotropic realizability holds if and only if the normal derivatives of u on each side of the gradient discontinuity interfaces have the same sign. Some examples of conductivity reconstruction are given.
Eingeschränkte Schlafqualität als indirekte psychosoziale Folge einer
Fazialisparese
Authors: Worrack Susanne , Guntinas-Lichius Orlando , Volk Gerd Fabian , Kaczmarek Magdalena C. , Mühleck Julia , Brenk-Franz Katja , Strauß Bernhard M. , Altmann Uwe
Published: March 2018

Hintergrund Fazialisparese (FP) ist eine Lähmung der Gesichtsmuskulatur und zählt zu den häufigsten
motorischen Ausfällen. Sie geht mit einer starken Beeinträchtigung der Lebensqualität und depressiven
Symptomen einher. Schlafstörungen in Folge einer FP werden oft auf krankheitsbedingte Beeinträchtigungen
zurückgeführt, obwohl auch psychosoziale Belastungen als Ursache in Frage kämen. Diese Studie untersuchte
direkte und indirekte Effekte der FP auf die Schlafqualität.

Methoden Die Stichprobe der Querschnittsstudie umfasste N = 81 FP-Patienten. Es wurden Symptome der
Gesichtsnervenlähmung (FACE), Schlafqualität (PSQI), Lebensqualität (SF36), Depressivität (PHQ9), soziale
Ängste (LSAS) und soziodemographische Daten erfasst. Mit Mediationsmodellen wurden Zusammenhänge zwischen
Symptomen der FP, sozialen Ängsten, Depressivität und Schlafqualität untersucht.

Ergebnisse Die Schlafqualität war bei 33,3 % der Patienten verringert. Die subjektiv eingeschätzte
Schwere der FP korrelierte mit der Schlafqualität. Mediationsanalysen legen eine Kausalkette zwischen der
Schwere der FP, sozialen Ängsten, depressiven Symptomen und einer eingeschränkten Schlafqualität nahe. Wurden
soziale Ängste und Depressivität als Mediatoren in das Modell aufgenommen, gab es keine direkten Effekte der
FP auf die Schlafqualität.

Schlussfolgerung Schlafprobleme im Kontext einer FP scheinen weniger durch die krankheitsbedingten
Beeinträchtigung verursacht, als vielmehr eine indirekte Folge: Die mit einer FP eingehergehende Veränderung
des Gesichtes verursacht psychische Beschwerden welche wiederum zu verminderter Schlafqualität führen. Die
medizinische Versorgung von FP-Patienten sollte deshalb auch die psychosozialen Folgen in den Blick nehmen, um
der Entstehung psychischer Störungen (z. B. Depressionen) und Schlafstörungen vorzubeugen.
Dosimetrie bei der Selektiven Internen Radiotherapie (SIRT)
Authors: Großer Oliver , Genseke Philipp , Kreißl Michael
Published: March 2018

Für die Berechnung der Therapieaktivität im Rahmen der Selektiven Internen Radiotherapie (SIRT oder auch Radioembolisation) existieren unterschiedlich elaborierte Berechnungsmodelle. Diese besitzen empirischen Charakter bzw. basieren auf makroskopischen Ansätzen unter der Annahme einer Gleichverteilung der Mikrosphären und damit der akkumulierten Dosis (MIRD-basierter Modellansatz). Eine Inhomogenität in der Anreicherung des Radioembolisats, welche regulär durch die post-therapeutische Bildgebung beobachtet wird, findet in den Dosierungskonzepten keine Berücksichtigung. Für die weitere Entwicklung wäre es hier wünschenswert, radiobiologische Konzepte stärker zu integrieren und eine Dosierung der Therapieaktivität unter Berücksichtigung der (limitierenden) gewebsspezifischen Toleranzen durchzuführen.

Generell sind die Bewertung der Effektivität und der Nebenwirkungen sowie die damit verbundene Definition von Toleranzdosen/Zieldosen schwierig. Die verfügbaren Daten weisen aufgrund der Heterogenität der untersuchten Endpunkte, unterschiedlicher basaler Leberfunktion und individueller Erkrankungshistorien (Vortherapie) eine große Streuung und eine damit verbundene große Unsicherheit auf.
Dosimetrie bei der Radionuklidtherapie mit Lu-177
Authors: Gosewisch Astrid , Ilhan Harun , Vomacka Lena , Böning Guido
Published: March 2018

Die Radioligandentherapie (RLT) mit radioaktiv markierten PSMA-Liganden (z. B. Lu-177-PSMA-617) und die Peptid-Rezeptor-Radionuklidtherapie (PRRT) mit radioaktiv markierten Somatostatin-Analoga (z. B. Lu-177-DOTATATE) haben sich über die letzten Jahre als vielversprechende Therapieoptionen bei metastasierten, kastrationsresistenten Prostatakarzinomen bzw. inoperablen oder metastasierten neuroendokrinen Tumoren entwickelt. Das Theragnostiknuklid Lu-177 weist dabei neben der Therapie-relevanten Beta-Minus-Komponente eine, auch für die Bildgebung gut nutzbare, Gammaemission auf, die eine direkte quantitative Bildgebung und Dosimetrie der Radiopharmakonverteilung möglich macht. Die Patienten-spezifische 3D-Dosimetrie auf Basis der quantitativen Lu-177-Bildgebung ist dabei der Schlüssel hin zur individualisierten Therapiekontrolle und -planung in der RLT und PRRT, in denen bisher vornehmlich noch standardisierte Aktivitätsmengen verabreicht werden. Jedoch ist die Ermittlung robuster Dosiswerte klinisch aufwändig, sowohl bez. des Messaufwands als auch hinsichtlich der Auswertung der Daten, und die starke Variabilität der Dosiswerte und deren Abhängigkeit von der verwendeten Methodik erschweren die Etablierung Therapie-spezifischer Dosis-Wirkungsbeziehungen. Gerade der Vergleich von Dosimetriedaten zwischen den Kliniken erfordert eine systematische und vereinheitlichte Dosimetrie mit akzeptablem klinischem Aufwand. Die Genauigkeit der Dosimetrie ist derzeit v. a. limitiert durch Effekte der Bildgebung. Zusätzliche Fehler können sich bspw. durch eine ungünstige Wahl der gemessenen Datenpunkte, Bewegungsartefakte, Überlagerungseffekte in der planaren Bildgebung oder durch eine nicht vollständig klinisch durchführbare Definition der Zielregion (z. B. Knochenmark) ergeben. Die 3D-Dosimetrie, unter Berücksichtigung zusätzlicher physikalischer oder biologischer Parameter (z. B. Dosisrate), kann in der Radionuklidtherapie einen wichtigen Beitrag zur Etablierung von Dosis-Wirkungsbeziehungen liefern, allerdings ist die klinisch-physiologische Interpretation der 3D-Dosisverteilungen derzeit noch stark limitiert durch Bildartefakte und Bildrauschen in den zur Dosimetrie eingesetzten SPECT-Bildern.
Describing chaotic attractors: Regular and perpetual points
Authors: Dudkowski Dawid , Prasad Awadhesh , Kapitaniak Tomasz
Published: March 2018

We study the concepts of regular and perpetual points for describing the behavior of chaotic attractors in dynamical systems. The idea of these points, which have been recently introduced to theoretical investigations, is thoroughly discussed and extended into new types of models. We analyze the correlation between regular and perpetual points, as well as their relation with phase space, showing the potential usefulness of both types of points in the qualitative description of co-existing states. The ability of perpetual points in finding attractors is indicated, along with its potential cause. The location of chaotic trajectories and sets of considered points is investigated and the study on the stability of systems is shown. The statistical analysis of the observing desired states is performed. We focus on various types of dynamical systems, i.e., chaotic flows with self-excited and hidden attractors, forced mechanical models, and semiconductor superlattices, exhibiting the universality of appearance of the observed patterns and relations.
PDV-based estimation of ejecta particles’ mass-velocity function from shock-loaded tin experiment
Authors: Franzkowiak J.-E. , Prudhomme G. , Mercier P. , Lauriot S. , Dubreuil E. , Berthe L.
Published: March 2018

A metallic tin plate with a given surface finish of wavelength λ ≃ 60 μm and amplitude h ≃ 8 μm is explosively driven by an electro-detonator with a shock-induced breakout pressure PSB = 28 GPa (unsupported). The resulting dynamic fragmentation process, the so-called “micro-jetting,” is the creation of high-speed jets of matter moving faster than the bulk metallic surface. Hydrodynamic instabilities result in the fragmentation of these jets into micron-sized metallic particles constituting a self-expanding cloud of droplets, whose areal mass, velocity, and particle size distributions are unknown. Lithium-niobate-piezoelectric sensor measured areal mass and Photonic Doppler Velocimetry (PDV) was used to get a time-velocity spectrogram of the cloud. In this article, we present both experimental mass and velocity results and we relate the integrated areal mass of the cloud to the PDV power spectral density with the assumption of a power law particle size distribution. Two models of PDV spectrograms are described. The first one accounts for the speckle statistics of the spectrum and the second one describes an average spectrum for which speckle fluctuations are removed. Finally, the second model is used for a maximum likelihood estimation of the cloud’s parameters from PDV data. The estimated integrated areal mass from PDV data is found to agree well with piezoelectric results. We highlight the relevance of analyzing PDV data and correlating different diagnostics to retrieve the physical properties of ejecta particles.
Evolution of dense spatially modulated electron bunches
Authors: Balal N. , Bratman V. L. , Friedman A.
Published: March 2018

An analytical theory describing the dynamics of relativistic moving 1D electron pulses (layers) with the density modulation affected by a space charge has been revised and generalized for its application to the formation of dense picosecond bunches from linear accelerators with laser-driven photo injectors, and its good agreement with General Particle Tracer simulations has been demonstrated. Evolution of quasi-one-dimensional bunches (disks), for which the derived formulas predict longitudinal expansion, is compared with that for thin and long electron cylinders (threads), for which the excitation of non-linear waves with density spikes was found earlier by Musumeci et al. [Phys. Rev. Lett. 106(18), 184801 (2011)] and Musumeci et al. [Phys. Rev. Spec. Top. --Accel. Beams 16(10), 100701 (2013)]. Both types of bunches can be used for efficiency enhancement of THz sources based on the Doppler frequency up-shifted coherent spontaneous radiation of electrons. Despite the strong Coulomb repulsion, the periodicity of a preliminary modulation in dense 1D layers persists during their expansion in the most interesting case of a relatively small change in particle energy. However, the period of modulation increases and its amplitude decreases in time. In the case of a large change in electron energy, the uniformity of periodicity is broken due to different relativistic changes in longitudinal scales along the bunch: the “period” of modulation decreases and its amplitude increases from the rear to the front boundary. Nevertheless, the use of relatively long electron bunches with a proper preliminary spatial modulation of density can provide a significantly higher power and a narrower spectrum of coherent spontaneous radiation of dense bunches than in the case of initially short single bunches with the same charge.
On the force–velocity relationship of a bundle of rigid bio-filaments
Authors: Perilli Alessia , Pierleoni Carlo , Ciccotti Giovanni , Ryckaert Jean-Paul
Published: March 2018

In various cellular processes, bio-filaments like F-actin and F-tubulin are able to exploit chemical energy associated with polymerization to perform mechanical work against an obstacle loaded with an external force. The force–velocity relationship quantitatively summarizes the nature of this process. By a stochastic dynamical model, we give, together with the evolution of a staggered bundle of Nf rigid living filaments facing a loaded wall, the corresponding force–velocity relationship. We compute the evolution of the model in the infinite wall diffusion limit and in supercritical conditions (monomer density reduced by critical density ρ^1>1), and we show that this solution remains valid for moderate non-zero values of the ratio between the wall diffusion and the chemical time scales. We consider two classical protocols: the bundle is opposed either to a constant load or to an optical trap setup, characterized by a harmonic restoring force. The constant load case leads, for each F value, to a stationary velocity Vstat(F;Nf,ρ^1) after a relaxation with characteristic time τmicro(F). When the bundle (initially taken as an assembly of filament seeds) is subjected to a harmonic restoring force (optical trap load), the bundle elongates and the load increases up to stalling over a characteristic time τOT. Extracted from this single experiment, the force–velocity VOT(F;Nf,ρ^1) curve is found to coincide with Vstat(F;Nf,ρ^1), except at low loads. We show that this result follows from the adiabatic separation between τmicro and τOT, i.e., τmicro ≪ τOT.