bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon nanopowder as diffuse rear reflector for silicon solar cells
Authors: Schäfer S. , Haase F. , Peibst R. , Brendel R.
Published: August 2017

Highly efficient solar cells require minimized recombination and maximized optical absorption. We apply Si nanopowder with a median particle size of 500 nm to the rear side of poly-Si on oxide (POLO) passivated Si wafers that have a planar front side. The enhanced optical absorption consists of a useful component from the wafer and useless absorption by the Si pigments and the poly-Si layer. We derive and successfully apply an analytical model that accounts for both contributions and for the light trapping that is caused by light scattering at the nanopowder layer. We measure and model that this rear side increases the photogenerated current density by 1.3 mA/cm2 for a 140 μm-thick planar cell. We compare the performance of the Si-pigmented diffuse rear side reflectors (PDR) with reflectors using random pyramids (RPs) and POLO junctions. We find that for full surface coverage by Si nanopowder, the better surface passivation compensates for an inferior optical performance of a PDR when compared to RP.
Partial spin absorption induced magnetization switching and its voltage-assisted improvement in an asymmetrical all spin logic device at the mesoscopic scale
Authors: Zhang Yue , Zhang Zhizhong , Wang Lezhi , Nan Jiang , Zheng Zhenyi , Li Xiang , Wong Kin , Wang Yu , Klein Jacques-Olivier , Khalili Amiri Pedram , Zhang Youguang , Wang Kang L. , Zhao Weisheng
Published: August 2017

Beyond memory and storage, future logic applications put forward higher requirements for electronic devices. All spin logic devices (ASLDs) have drawn exceptional interest as they utilize pure spin current instead of charge current, which could promise ultra-low power consumption. However, relatively low efficiencies of spin injection, transport, and detection actually impede high-speed magnetization switching and challenge perspectives of ASLD. In this work, we study partial spin absorption induced magnetization switching in asymmetrical ASLD at the mesoscopic scale, in which the injector and detector have the nano-fabrication compatible device size (>100 nm) and their contact areas are different. The enlarged contact area of the detector is conducive to the spin current absorption, and the contact resistance difference between the injector and the detector can decrease the spin current backflow. Rigorous spin circuit modeling and micromagnetic simulations have been carried out to analyze the electrical and magnetic features. The results show that, at the fabrication-oriented technology scale, the ferromagnetic layer can hardly be switched by geometrically partial spin current absorption. The voltage-controlled magnetic anisotropy (VCMA) effect has been applied on the detector to accelerate the magnetization switching by modulating magnetic anisotropy of the ferromagnetic layer. With a relatively high VCMA coefficient measured experimentally, a voltage of 1.68 V can assist the whole magnetization switching within 2.8 ns. This analysis and improving approach will be of significance for future low-power, high-speed logic applications.
An angularly stable dual-broadband anisotropic cross polarization conversion metasurface
Authors: Khan M. Ismail , Tahir Farooq A.
Published: August 2017

A dual broadband anisotropic cross-polarization-conversion (CPC) metasurface is designed and tested. The unit cell of the proposed metasurface consists of a two-slit rectangular split-ring-resonator inside of which a metallic cross element is placed. The unit cell is printed on a dielectric substrate backed by a metallic plane. Excellent CPC is achieved in two wide frequency bands from 5 to 9.7 GHz (4.7 GHz bandwidth) and from 11.2 to 15 GHz (3.8 GHz bandwidth) for both normal and oblique incidences. The wide CPC bandwidth is due to the plasmonic resonances occurring at three distinct frequencies. The unique physical structure, sub-wavelength size, and electrically small substrate thickness make the response of the metasurface identical for both x and y polarizations and insensitive to incidence angles (up to 60°). The physical mechanism behind polarization conversion is also elucidated through surface current distribution and through the concept of a high impedance surface. The proposed design is validated by full-wave simulations and experimental measurements.
Thermal elastic-wave attenuation in low-dimensional SiNx bars at low temperatures
Authors: Withington S. , Williams E. , Goldie D. J. , Thomas C. N. , Schneiderman M.
Published: August 2017

At low temperatures, <200 mK, the thermal flux through low-dimensional amorphous dielectric bars, <2 μm wide and 200 nm thick, is transported by a small number of low-order elastic modes. For long bars, L > 400 μm, it is known that the conductance scales as 1/L, where L is the length, but for short bars, 1 μm < L < 400 μm, the length dependence is poorly known. Although it is assumed that the transport must exhibit a diffusive to ballistic transition, the functional form of the transition and the scale size over which the transition occurs have not, to our knowledge, been measured. In this paper, we use ultra-low-noise superconducting Transition Edge Sensors to measure the heat flux through a set of SiNx bars to establish the characteristic scale size of the ballistic to diffusive transition. For bars supporting 6 to 7 modes, we measure a thermal elastic-wave attenuation length of 20 μm. The measurement is important because it sheds light on the scattering processes, which in turn are closely related to the generation of thermal fluctuation noise. Our own interest lies in creating patterned phononic filters for controlling heat flow and thermal noise in ultra-low-noise devices, but the work will be of interest to others trying to isolate devices from their environments and studying loss mechanisms in micro-mechanical resonators.
Ultra-wideband polarization-insensitive and wide-angle thin absorber based on resistive metasurfaces with three resonant modes
Authors: Li Long , Lv Zhiyong
Published: August 2017

In this paper, a metamaterial absorber is designed, fabricated, and experimentally demonstrated to realize ultra-wideband absorption, which is composed of three layers of square resistive metasurfaces with different dimensions. Multilayer resistive metasurfaces can not only broaden the absorption bandwidth but also adjust the impedance matching based on multi-resonant modes. The total thickness of the proposed absorber is 3.8 mm, which is only 0.09λ at the lowest frequency. The bandwidth of absorptivity more than 90% is from 7.0 GHz to 37.4 GHz, and the relative absorption bandwidth is about 137%. The proposed absorber has good polarization-insensitiveness and wide incident angle stability. The measured results agree well with the theoretical design and the numerical simulations.
Electronic properties of lithiated SnO-based anode materials
Authors: Bauer Dominik , Bunjaku Teutë , Pedersen Andreas , Luisier Mathieu
Published: August 2017

In this paper, we use an ab-initio quantum transport approach to study the electron current flowing through lithiated SnO anodes for potential applications in Li-ion batteries. By investigating a set of lithiated structures with varying lithium concentrations, it is revealed that Lix SnO can be a good conductor, with values comparable to bulk β-Sn and Li. A deeper insight into the current distribution indicates that electrons preferably follow specific trajectories, which offer superior conducting properties than others. These channels have been identified and it is shown here how they can enhance or deteriorate the current flow in lithiated anode materials.
A prickly subject: innovative handling of a difficult prey
Authors: Behrendorff Linda
Published: August 2017

Canids are generally considered to be ambush predators, but in island ecosystems adaptability and flexibility are essential for survival. Dingoes (Canis lupus dingo) attack and kill their prey in a variety of ways including utilising waterbodies. Here I document the drowning of an adult short-beaked echidna (Tachyglossus aculeatus) before consumption by a dingo using the coastal surf beach intertidal to shallow subtidal area on the eastern coast of Fraser Island (K’gari), highlighting an innovative prey-handling technique.
Use of urban bushland remnants by the western ringtail possum (Pseudocheirus occidentalis): short-term home-range size and habitat use in Albany, Western Australia
Authors: Van Helden Bronte E. , Speldewinde Peter C. , Close Paul G. , Comer Sarah J.
Published: August 2017

Management of wildlife in habitats fragmented by urbanisation requires an understanding of a species’ habitat use. Known populations of the critically endangered western ringtail possum (Pseudocheirus occidentalis) are largely restricted to bushland remnants in rapidly urbanising areas of south-western Australia. Habitat use is thought to be driven by nutritional content, structure and connectivity of canopy vegetation. At the southernmost extent of the species’ range, habitat use is largely unknown, although it is expected to be different from previous descriptions due to differences in vegetation characteristics. We used VHF and global positioning system tracking collars to determine short-term home-range size, diurnal refuge use and night-time tree use of western ringtail possums in bushland remnants within Albany City. Possums had small home ranges (0.88 ha) that were negatively correlated with percentage canopy cover; used a variety of daytime refuges (predominantly dreys); and preferentially utilised marri (Corymbia calophylla) and jarrah (Eucalyptus marginata) at night. These results confirm that differences in habitat use among populations exist and suggests that the species is reasonably flexible in its use of habitat. Management of western ringtail possums needs to be population specific and will benefit from further examination of habitat use in the variety of occupied habitats.
Tissue cell stress response to obesity and its interaction with late gestation diet
Authors: Saroha Vivek , Dellschaft Neele S. , Keisler Duane H. , Gardner David S. , Budge Helen , Sebert Sylvain P. , Symonds Michael E.
Published: August 2017

Intrauterine growth restriction in late pregnancy can contribute to adverse long-term metabolic health in the offspring. In the present study we used an animal (sheep) model of maternal dietary manipulation in late pregnancy, combined with exposure of the offspring to a low-activity, obesogenic environment after weaning, to characterise the effects on glucose homeostasis. Dizygotic twin-pregnant sheep were either fed to 60% of requirements (nutrient restriction (R)) or fed ad libitum (~140% of requirements (A)) from 110 days gestation until term (~147 days). After weaning (~3 months of age), the offspring were kept in either a standard (in order to remain lean) or low-activity, obesogenic environment. R mothers gained less weight and produced smaller offspring. As adults, obese offspring were heavier and fatter with reduced glucose tolerance, regardless of maternal diet. Molecular markers of stress and autophagy in liver and adipose tissue were increased with obesity, with gene expression of hepatic glucose-related protein 78 (Grp78) and omental activation transcription factor 6 (Atf6), Grp78 and ER stress degradation enhancer molecule 1 (Edem1) only being increased in R offspring. In conclusion, the adverse effect of juvenile-onset obesity on insulin-responsive tissues can be amplified by previous exposure to a suboptimal nutritional environment in utero, thereby contributing to earlier onset of insulin resistance.
Transmembrane allosteric energetics characterization for strong coupling between proton and potassium ion binding in the KcsA channel
Authors: Xu Yunyao , Bhate Manasi P. , McDermott Ann E.
Published: August 2017

Significance

Although C-type inactivation in potassium channels is crucial in many biological signaling processes, its mechanism is debated. We address a hypothesis that K
+
affinity reduction and ion loss due to allosterically coupled activation is a major factor in promoting inactivation. We show that in KcsA, activation by proton binding at the intracellular pH sensor can significantly reduce K
+
affinity at the extracellular selectivity filter, which would be expected to contribute to current cessation (inactivation). This allosteric coupling is substantially reduced by mutating a residue that connects the inner transmembrane helix hinge (involved in activation) to the base of the selectivity filter, thus providing clear evidence for the allosteric coupling network and explaining why this mutant is inactivationless.
Mouse macrophages show different requirements for phosphatidylserine receptor Tim4 in efferocytosis
Authors: Yanagihashi Yuichi , Segawa Katsumori , Maeda Ryota , Nabeshima Yo-ichi , Nagata Shigekazu
Published: August 2017

Significance

Every day, billons of cells undergo apoptosis, expose phosphatidylserine (PtdSer), and are engulfed by macrophages in a PtdSer-dependent manner. Here, we present that Tim4, a PtdSer receptor, strongly enhances Protein S- or growth arrest-specific 6-induced efferocytosis by TAM receptor-expressing phagocytes. Resident peritoneal macrophages, Kupffer cells, and CD169
+
skin macrophages required Tim4 for the efficient efferocytosis, whereas thioglycollate-elicited peritoneal macrophages and cultured microglia did not. These results indicate that the efferocytosis by different macrophages may have different physiological outcomes and, therefore, would contribute to the understanding of macrophage heterogeneity.
The birth of the memory of Communism: memorial museums in Europe
Authors: Zombory Máté
Published: August 2017

This article argues that the memory of Communism emerged in Europe not due to the public recognition of pre-given historical experiences of peoples previously under Communist regimes, but to the particularities of the post-Cold War transnational political context. As a reaction to the uniqueness claim of the Holocaust in the power field structured by the European enlargement process, Communism memory was reclaimed according to the European normative and value system prescribed by the memory of the Holocaust. Since in the political context of European enlargement refusing to cultivate the memory of the Holocaust was highly illegitimate, the memory of Communism was born as the “twin brother” of Holocaust memory. The Europeanized memory of Communism produced a legitimatedifferentia specificaof the newcomers in relation to old member states. It has been publicly reclaimed as an Eastern European experience in relation to universal Holocaust memory perceived as Western. By the analysis of memorial museums of Communism, the article provides a transnational, historical, and sociological account on Communism memory. It argues that the main elements of the discursive repertoire applied in post-accession political debates about the definition of Europe were elaborated before 2004 in a pan-European way.
Feasibility study on sc-Ar electroplating for metal coating fabrication
Authors: Chuang Ho-Chiao , Sanchez Jorge
Published: August 2017

For this preliminary work, Cu metal coatings were produced by electroplating under supercritical argon (sc-Ar) on copper sulphate bath with no additives. Coatings were also produced by supercritical carbon dioxide (sc-CO2) and traditional electroplating for comparison. Mechanical and electrical properties were analysed for all coatings. It was found that sc-CO2 electroplating had the highest grade of grain refinement; however, this meant relatively higher degree of internal stresses, while the sc-Ar electroplating displayed more moderate grain refinement, hence relatively lower internal stress. Advantages of the proposed the sc-Ar method are faster fabrication time compared to the traditional method and desirably lower internal stresses compared to the sc-CO2 method.
Sterol transporters at membrane contact sites regulate TORC1 and TORC2 signaling
Authors: Murley Andrew , Yamada Justin , Niles Bradley J. , Toulmay Alexandre , Prinz William A. , Powers Ted , Nunnari Jodi
Published: August 2017

Membrane contact sites (MCSs) function to facilitate the formation of membrane domains composed of specialized lipids, proteins, and nucleic acids. In cells, membrane domains regulate membrane dynamics and biochemical and signaling pathways. We and others identified a highly conserved family of sterol transport proteins (Ltc/Lam) localized at diverse MCSs. In this study, we describe data indicating that the yeast family members Ltc1 and Ltc3/4 function at the vacuole and plasma membrane, respectively, to create membrane domains that partition upstream regulators of the TORC1 and TORC2 signaling pathways to coordinate cellular stress responses with sterol homeostasis.
MRTF transcription and Ezrin-dependent plasma membrane blebbing are required for entotic invasion
Authors: Hinojosa Laura Soto , Holst Manuel , Baarlink Christian , Grosse Robert
Published: August 2017

Entosis is a nonapoptotic form of cell death initiated by actomyosin-dependent homotypic cell-in-cell invasion that can be observed in malignant exudates during tumor progression. We previously demonstrated formin-mediated actin dynamics at the rear of the invading cell as well as nonapoptotic plasma membrane (PM) blebbing in this cellular motile process. Although the contractile actin cortex involved in bleb-driven motility is well characterized, a role for transcriptional regulation in this process has not been studied. Here, we explore the impact of the actin-controlled MRTF–SRF (myocardin-related transcription factor–serum response factor) pathway for sustained PM blebbing and entotic invasion. We find that cortical blebbing is tightly coupled to MRTF nuclear shuttling to promote the SRF transcriptional activity required for entosis. Furthermore, PM blebbing triggered SRF-mediated up-regulation of the metastasis-associated ERM protein Ezrin. Notably, Ezrin is sufficient and important to sustain bleb dynamics for cell-in-cell invasion when SRF is suppressed. Our results highlight the critical role of the actin-regulated MRTF transcriptional pathway for bleb-associated invasive motility, such as during entosis.
Dialogue between centrosomal entrance and exit scaffold pathways regulates mitotic commitment
Authors: Chan Kuan Yoow , Alonso-Nuñez Marisa , Grallert Agnes , Tanaka Kayoko , Connolly Yvonne , Smith Duncan L. , Hagan Iain M.
Published: August 2017

The fission yeast scaffold molecule Sid4 anchors the septum initiation network to the spindle pole body (SPB, centrosome equivalent) to control mitotic exit events. A second SPB-associated scaffold, Cut12, promotes SPB-associated Cdk1–cyclin B to drive mitotic commitment. Signals emanating from each scaffold have been assumed to operate independently to promote two distinct outcomes. We now find that signals from Sid4 contribute to the Cut12 mitotic commitment switch. Specifically, phosphorylation of Sid4 by NIMAFin1 reduces Sid4 affinity for its SPB anchor, Ppc89, while also enhancing Sid4’s affinity for casein kinase 1δ (CK1δ). The resulting phosphorylation of Sid4 by the newly docked CK1δ recruits Chk2Cds1 to Sid4. Chk2Cds1 then expels the Cdk1–cyclin B antagonistic phosphatase Flp1/Clp1 from the SPB. Flp1/Clp1 departure can then support mitotic commitment when Cdk1–cyclin B activation at the SPB is compromised by reduction of Cut12 function. Such integration of signals emanating from neighboring scaffolds shows how centrosomes/SPBs can integrate inputs from multiple pathways to control cell fate.
The density of primes dividing a term in the Somos-5 sequence
Authors: Davis Bryant , Kotsonis Rebecca , Rouse Jeremy
Published: August 2017

The Somos-5 sequence is defined by

a

0

=

a

1

=

a

2

=

a

3

=

a

4

=
1

a_{0} = a_{1} = a_{2} = a_{3} = a_{4} = 1

and

a

m

=

a

m
−
1

a

m
−
4

+

a

m
−
2

a

m
−
3

a

m
−
5

a_{m} = \frac {a_{m-1} a_{m-4} + a_{m-2} a_{m-3}}{a_{m-5}}

for

m
≥
5

m \geq 5

. We relate the arithmetic of the Somos-5 sequence to the elliptic curve

E
:

y

2

+
x
y
=

x

3

+

x

2

−
2
x

E : y^{2} + xy = x^{3} + x^{2} - 2x

and use properties of Galois representations attached to

E
E

to prove the density of primes

p
p

dividing some term in the Somos-5 sequence is equal to

5087
10752

\frac {5087}{10752}

.
A 𝑞-series identity via the 𝔰𝔩₃ colored Jones polynomials for the (2,2𝔪)-torus link
Authors: Yuasa Wataru
Published: August 2017

The colored Jones polynomial is a

q
q

-polynomial invariant of links colored by irreducible representations of a simple Lie algebra. A

q
q

-series called a tail is obtained as the limit of the

s
l

2

\mathfrak {sl}_2

colored Jones polynomials

{

J
n

(
K
;
q
)

}
n

\{J_n(K;q)\}_n

for some link

K
K

, for example, an alternating link. For the

s
l

3

\mathfrak {sl}_3

colored Jones polynomials, the existence of a tail is unknown. We give two explicit formulas of the tail of the

s
l

3

\mathfrak {sl}_3

colored Jones polynomials colored by

(
n
,
0
)

(n,0)

for the

(
2
,
2
m
)

(2,2m)

-torus link. These two expressions of the tail provide an identity of

q
q

-series. This is a knot-theoretical generalization of the Andrews–Gordon identities for the Ramanujan false theta function.
Sphingolipids facilitate age asymmetry of membrane proteins in dividing yeast cells
Authors: Singh Pushpendra , Ramachandran Sree Kumar , Zhu Jin , Kim Byoung Choul , Biswas Debojyoti , Ha Taekjip , Iglesias Pablo A. , Li Rong
Published: August 2017

One proposed mechanism of cellular aging is the gradual loss of certain cellular components that are insufficiently renewed. In an earlier study, multidrug resistance transporters (MDRs) were postulated to be such aging determinants during the yeast replicative life span (RLS). Aged MDR proteins were asymmetrically retained by the aging mother cell and did not diffuse freely into the bud, whereas newly synthesized MDR proteins were thought to be deposited mostly in the bud before cytokinesis. In this study, we further demonstrate the proposed age asymmetry of MDR proteins in dividing yeast cells and investigate the mechanism that controls diffusive properties of MDR proteins to maintain this asymmetry. We found that long-chain sphingolipids, but not the septin/endoplasmic reticulum–based membrane diffusion barrier, are important for restricting MDR diffusion. Depletion of sphingolipids or shortening of their long acyl chains resulted in an increase in the lateral mobility of MDR proteins, causing aged MDR protein in the mother cell to enter the bud. We used a mathematical model to understand the effect of diminished MDR age asymmetry on yeast cell aging, the result of which was qualitatively consistent with the observed RLS shortening in sphingolipid mutants.
Uncertain Times
Authors: Powell Suzanne K.
Published: August 2017

Our health care environment is more uncertain than ever. Uncertainty may lead to stress, burnout, disengagement, or worse. This Editorial discusses causes and potential attitudes to mitigate those feelings, making for a more satisfied employee and more effective patient care.
Appropriate Use Criteria for Cardiac Computed Tomography: Impact on Diagnostic Utility
Authors: Bami Karan , Premaratne Manuja , Lamba Jasmine , Yam Yeung , Hossain Alomgir , Keenan Marissa , Haddad Tony , Anand Saipriya , Burwash Ian G. , Ruddy Terrence D. , Dwivedi Girish , Chow Benjamin J.W.
Published: August 2017

Background

Appropriate Use Criteria (AUC) guidelines for cardiac computed tomography (CCT) were developed to limit testing to reasonable clinical settings. However, significant testing is still done for inappropriate indications. This study investigates the impact of AUC on evaluability of CCT to determine if inappropriate tests result in a greater proportion of nondiagnostic results.

Methods

Investigators reviewed the medical records of 2417 consecutive patients who underwent CCT at the University of Ottawa Heart Institute. We applied the 2010 AUC and classified them as appropriate, inappropriate, or uncertain. Unclassifiable tests, as well as those with uncertain appropriateness, were excluded from the final analysis. Cardiac computed tomography results were classified as diagnostic if (1) all coronary segments were visualized, evaluable, and without obstructive stenosis; or (2) obstructive coronary artery disease with greater than 50% diameter stenosis in at least 1 coronary artery. All other test results were considered nondiagnostic.

Results

Of the 1984 patients included in the final analysis, 1522 patients (76.7%) had indications that were appropriate, whereas the remaining 462 (23.3%) were inappropriate. Inappropriate tests resulted in a higher rate of nondiagnostic results compared with appropriate CCT (9.0% vs 6.2%, P = 0.034). Inappropriate tests also had significantly more studies with nonevaluable segments than appropriate tests (24.5% vs 16.4%, P < 0.001) and were more likely to reveal obstructive coronary disease than appropriate CCT (50.5% vs 32.7%, P < 0.001).

Conclusions

Cardiac computed tomography done for inappropriate indications may be associated with lower diagnostic yield and could impact future downstream resource utilization and health care costs.
Experience With Iterative Reconstruction Techniques for Abdominopelvic Computed Tomography in Morbidly and Super Obese Patients
Authors: Shaqdan Khalid W. , Kambadakone Avinash R. , Hahn Peter , Sahani Dushyant V.
Published: August 2017

Objective

The aim of this study was to investigate the diagnostic performance of abdominopelvic computed tomography (CT) images reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) algorithms in morbidly and super obese patients.

Materials and Methods

One hundred eighty-seven abdominopelvic CT examinations in portal venous phase were performed between February 2015 and February 2016 in 182 patients (mean age = 52 years, mean body mass index = 45.5). One hundred fourteen of 187 examinations were reconstructed using IR and 73 examinations were processed using FBP. Patients were further stratified based on body mass index. Sixty CT scans were reviewed by a single reader for image quality, image noise, and artifacts. Objective noise and attenuation were also determined. Size-specific dose estimate and CT dose index volume were compared and statistically analyzed.

Results

A diagnostic interpretation was rendered for all 187 examinations. A single-reader review of 60 cases showed greater diagnostic acceptability for IR when compared with FBP (image quality = 4.2 and 3.8 [P = 0.035], noise = 1.5 and 1.6 [P = 0.692], artifact = 1.4 and 1.5 [P = 0.759], respectively). For all examinations, the IR group had lower objective image noise (IR = 9.3 and FBP = 14.3; P < 0.001) and higher contrast-to-noise ratio (IR = 17.2 and FBP = 11.7; P < 0.001) without increase in radiation dose (size-specific dose estimate [IR = 15.1, FBP = 16.5 mGy; P = 0.045] and CT dose index volume [IR = 17.6, FBP = 18 mGy; P = 0.62]).

Conclusions

In morbidly and super obese patients, diagnostic quality images could be reliably generated with minimal artifacts and noise using newer generation scanners integrated with IR without increasing radiation dose.
Comparison of Delay-Sensitive and Delay-Insensitive Computed Tomography Perfusion Methods in Acute Ischemic Stroke and Their Variability According to Location of Critical Vascular Stenosis
Authors: Karaalioglu Banu , Aralasmak Ayse , Toprak Huseyin , Kolukisa Mehmet , Uysal Omer , Yildiz Seyma , Ozdemir Huseyin , Alkan Alpay
Published: August 2017

Objective

The aim of this study was to evaluate visual and quantitative differences of delay-sensitive (singular value deconvolution [SVD]) and delay-insensitive (SVD+) computed tomography perfusion (CTP) postprocessing methods in acute ischemic stroke patients and their variability according to location of critical stenosis.

Methods

The CTPs of 45 patients were retrospectively processed with 2 different methods. Comparing with the contralateral normal hemisphere, relative and difference of metrics were calculated (relative cerebral blood volume, relative cerebral blood flow [rCBF], relative mean transite time [rMTT], and difference mean transite time [dMTT]). Patients were categorized into 5 groups according to superiority in visual assessment of penumbra between postprocessing methods. Locations of critical stenosis and their percentages in each group were identified and compared.

Results

Differences were formulated as (rCBF/1.4, rMTT × 1.4, dMTT/3.8) SVD = (rCBF, rMTT, dMTT) SVD+. In group 1, penumbra was noted in SVD, whereas pseudohyperperfusion was noted in SVD+. In groups 2 and 3, penumbra was better distinguished in SVD than in SVD+ in decreasing easiness, respectively. In group 4, penumbra assessment was similar in both. In group 5, penumbra was better distinguished in SVD+. Groups 1 and 5 were the groups in which the frequency of critical distal stenosis was 100%. Groups 2, 3, and 4 were the groups having high rates of proximal critical stenosis in decreasing proportions, respectively (90%, 87%, and 77%).

Conclusions

In both CTP methods, the most prominent difference was found in dMTT. Visually, penumbra was better distinguished by SVD in proximal critical stenosis, whereas was better distinguished by SVD+ in distal critical stenosis. In cases having both ipsilateral critical proximal and distal stenoses, penumbra was noted in SVD but pseudohyperperfusion in SVD+. This finding showed that extraction of contrast delay in the SVD+ method might cause false results in cases of ipsilateral critical proximal and distal stenoses.
Intravoxel Incoherent Motion Diffusion-Weighted Imaging Versus Dynamic Contrast-Enhanced Magnetic Resonance Imaging: Comparison of the Diagnostic Performance of Perfusion-Related Parameters in Breast
Authors: Jiang Lei , Lu Xu , Hua Bin , Gao Jiayin , Zheng Dandan , Zhou Yiming
Published: August 2017

Objective

The aim of this study was to investigate the diagnostic performance of the perfusion-related parameters of intravoxel incoherent motion (IVIM) imaging for breast lesions, compared with dynamic contrast-enhanced magnetic resonance imaging (DCE MRI).

Methods

Fifty-nine patients with both IVIM imaging and subsequent DCE MRI were enrolled. Perfusion-related parameters of IVIM imaging (perfusion fraction, f; pseudo–diffusion coefficient, D*), as well as model-based and model-free parameters of DCE MRI, were measured. Receiver operating characteristic curve analysis and correlations between the IVIM and DCE MRI parameters were performed.

Results

Thirty-one malignant and 35 benign lesions were pathologically proved. The area under the receiver operating characteristic curves (AUC) of D* plus f (AUC
f+D*) was 0.834. The combined AUC of all model-based DCE MRI parameters (AUCmodel-based) was 0.904. The combined AUC of all model-free DCE MRI parameters (AUCmodel-free) was 0.876. AUC
f+D* had no significant difference with either AUCmodel-based or AUCmodel-free. No significant correlation was found between f or D* and DCE-derived parameters.

Conclusions

Intravoxel incoherent motion imaging has the same value in differentiating malignant and benign breast lesions, compared with DCE MRI, in terms of perfusion-related parameters.
Incomplete MyoD-induced transdifferentiation is associated with chromatin remodeling deficiencies
Authors: Manandhar Dinesh , Song Lingyun , Kabadi Ami , Kwon Jennifer , Edsall Lee , Ehrlich Melanie , Tsumagari Koji , Gersbach Charlie , Crawford Gregory , Gordan Raluca
Published: August 2017

Our current understanding of cellular transdifferentiation systems is limited. It is oftentimes unknown, at a genome-wide scale, how much transdifferentiated cells differ quantitatively from both the starting cells and the target cells. Focusing on transdifferentiation of primary human skin fibroblasts by forced expression of myogenic transcription factor MyoD, we performed quantitative analyses of gene expression and chromatin accessibility profiles of transdifferentiated cells compared to fibroblasts and myoblasts. In this system, we find that while many of the early muscle marker genes are reprogrammed, global gene expression and accessibility changes are still incomplete when compared to myoblasts. In addition, we find evidence of epigenetic memory in the transdifferentiated cells, with reminiscent features of fibroblasts being visible both in chromatin accessibility and gene expression. Quantitative analyses revealed a continuum of changes in chromatin accessibility induced by MyoD, and a strong correlation between chromatin-remodeling deficiencies and incomplete gene expression reprogramming. Classification analyses identified genetic and epigenetic features that distinguish reprogrammed from non-reprogrammed sites, and suggested ways to potentially improve transdifferentiation efficiency. Our approach for combining gene expression, DNA accessibility, and protein-DNA binding data to quantify and characterize the efficiency of cellular transdifferentiation on a genome-wide scale can be applied to any transdifferentiation system.
An orphancbb3-type cytochrome oxidase subunit supportsPseudomonas aeruginosabiofilm growth and virulence
Authors: Jo Jeanyoung , Cortez Krista L. , Cornell William C. , Price-Whelan Alexa , Dietrich Lars E.P.
Published: August 2017

Hypoxia is a common challenge faced by bacteria during associations with hosts due in part to the formation of densely packed communities (biofilms).cbb3-type cytochromecoxidases, which catalyze the terminal step in respiration and have a high affinity for oxygen, have been linked to bacterial pathogenesis. The pseudomonads are unusual in that they often contain multiple full and partial (i.e., “orphan”) operons forcbb3-type oxidases and oxidase subunits. Here, we describe a unique role for the orphan catalytic subunit CcoN4 in colony biofilm development and respiration in the opportunistic pathogenP. aeruginosaPA14. We also show that CcoN4 contributes to the reduction of phenazines, antibiotics that support redox balancing for cells in biofilms, and to virulence in aCaenorhabditis elegansmodel of infection. These results highlight the relevance of the colony biofilm model to pathogenicity and underscore the potential ofcbb3-type oxidases as therapeutic targets.
Mechanistic hierarchical population model identifies latent causes of cell-to-cell variability
Authors: Loos Carolin , Moeller Katharina , Fröhlich Fabian , Hucho Tim , Hasenauer Jan
Published: August 2017

All biological systems exhibit cell-to-cell variability, and this variability often has functional implications. To gain a thorough understanding of biological processes, the latent causes and underlying mechanisms of this variability must be elucidated. Cell populations comprising multiple distinct subpopulations are commonplace in biology, yet no current methods allow the sources of variability between and within individual subpopulations to be identified. This limits the analysis of single-cell data, for example provided by flow cytometry and microscopy. In this study, we present a data-driven modeling framework for the analysis of populations comprising heterogeneous subpopulations. Our approach combines mixture modeling with frameworks for distribution approximation, facilitating the integration of multiple single-cell datasets and the detection of causal differences between and within subpopulations. The computational efficiency of our framework allows hundreds of competing hypotheses to be compared, giving unprecedented depth of a study. We demonstrated the ability of our method to capture multiple levels of heterogeneity in the analyzes of simulated data and data from highly heterogeneous sensory neurons involved in pain initiation. Our approach identified the sources of cell-to-cell variability and revealed mechanisms that underlie the modulation of nerve growth factor-induced Erk1/2 signaling by extracellular scaffolds.
Evaluating anthropogenic noise impacts on animals in natural areas
Authors: Keyel Alexander C. , Reed Sarah E. , Nuessly Kathryn , Cinto-Mejia Elizeth , Barber Jesse R. , Wittemyer George
Published: August 2017

Noise pollution is detrimental to a diversity of animal species and degrades natural areas, raising concern over the expanding footprint of anthropogenic noise on ecosystems. To guide management of noise sources, modeling tools have been developed to quantify noise levels across landscapes.

We demonstrate how to model anthropogenic noise using sound propagation models, including noise from point, line, and polygon sources. In addition, we demonstrate three ways of evaluating spatially-explicit noise impacts, by identifying where noise 1) exceeds a sound level threshold, 2) is audible, or 3) has the potential to mask species communications. Finally, we examine approaches to mitigate these noise impacts on animal species.

Noise sources in locations more favorable to sound propagation (e.g., locations with long, unobstructed lines-of-sight) will have a disproportionate impact on the surrounding area. We demonstrate how propagation models can identify sites with smaller acoustic footprints or sites that would benefit from additional noise-control measures.

Modeling decisions, such as choice of sound propagation model, sound source information, and the quality of the input data, strongly influence the accuracy of model predictions. These decisions can be guided by comparing model predictions to empirical data when it is available.

Synthesis and applications: Here, we demonstrate an approach for modeling and assessing anthropogenic noise sources across a landscape. Our versatile approach allows refining propagation outputs for species-specific questions as well as the quantitative evaluation of management alternatives. While the results are presented in the context of particular species, these approaches can be applied more generally to a wide range of taxa or used for multispecies assessments.
Functional histamine H3and adenosine A2Areceptor heteromers in recombinant cells and rat striatum
Authors: Márquez-Gómez Ricardo , Gutiérrez-Rodelo Citlaly , Robins Meridith T. , Arias Juan-Manuel , Olivares-Reyes Jesús-Alberto , van Rijn Richard M. , Arias-Montaño José-Antonio
Published: August 2017

In the striatum, histamine H3receptors (H3Rs) are co-expressed with adenosine A2Areceptors (A2ARs) in the cortico-striatal glutamatergic afferents and the GABAergic medium-sized spiny neurons that originate the indirect pathway of the basal ganglia. This location allows H3Rs and A2ARs to regulate the striatal GABAergic and glutamatergic transmission. However, whether these receptors interact to modulate the intra-striatal synaptic transmission has not yet been assessed. To test this hypothesis a heteromer-selectivein vitroassay was used to detect functional complementation between a chimeric A2AR302-Gαqi4and wild-type H3Rs in transfected HEK-293 cells. H3R activation with the agonist RAMH resulted in Ca2+mobilization (pEC507.31 ± 0.23; maximal stimulation, Emax 449 ± 25 % of basal) indicative of receptor heterodimerization. This response was not observed with histamine, suggesting a RAMH bias for heteromers. Functional A2AR-H3R heteromers were confirmed by co-immunoprecipitation and observations of differential cAMP signaling when both receptors were co-expressed in the same cell. In membranes from rat striatal synaptosomes, H3R activation decreased A2AR affinity for the agonist CGS-21680 (pKi values 8.10 ± 0.04 and 7.70 ± 0.04). Moreover, H3Rs and A2ARs co-immunoprecipitated in protein extracts from striatal synaptosomes. These results support the existence of a H3R/A2AR heteromer, and reveal a new mechanism by which these receptors may modulate the unction of the striatum and the basal ganglia.
Heterogeneity and Intrinsic Variation in Spatial Genome Organization
Authors: Finn Elizabeth H. , Pegoraro Gianluca , Brandão Hugo B. , Valton Anne-Laure , Oomen Marlies E. , Dekker Job , Mirny Leonid , Misteli Tom
Published: August 2017

The genome is hierarchically organized in 3D space and its architecture is altered in differentiation, development and disease. Some of the general principles that determine global 3D genome organization have been established. However, the extent and nature of cell-to-cell and cell-intrinsic variability in genome architecture are poorly characterized. Here, we systematically probe the heterogeneity in genome organization in human fibroblasts by combining high-resolution Hi-C datasets and high-throughput genome imaging. Optical mapping of several hundred genome interaction pairs at the single cell level demonstrates low steady-state frequencies of colocalization in the population and independent behavior of individual alleles in single nuclei. Association frequencies are determined by genomic distance, higher-order chromatin architecture and chromatin environment. These observations reveal extensive variability and heterogeneity in genome organization at the level of single cells and alleles and they demonstrate the coexistence of a broad spectrum of chromatin and genome conformations in a cell population.
Heterologous expression of the immune receptorEFRinMedicago truncatulareduces pathogenic infection, but not rhizobial symbiosis
Authors: Pfeilmeier Sebastian , George Jeoffrey , Morel Alice , Roy Sonali , Smoker Matthew , Stransfeld Lena , Downie J. Allan , Peeters Nemo , Malone Jacob G. , Zipfel Cyril
Published: August 2017

Interfamily transfer of plant pattern recognition receptors (PRRs) represents a promising biotechnological approach to engineer broad-spectrum, and potentially durable, disease resistance in crops. It is however unclear whether new recognition specificities to given pathogen-associated molecular patterns (PAMPs) affect the interaction of the recipient plant with beneficial microbes. To test this in a direct reductionist approach, we transferred theBrassicaceae-specific PRR ELONGATION FACTOR-THERMO UNSTABLE RECEPTOR (EFR) fromArabidopsis thalianato the legumeMedicago truncatula, conferring recognition of the bacterial EF-Tu protein. ConstitutiveEFRexpression led to EFR accumulation and activation of immune responses upon treatment with the EF-Tu-derived elf18 peptide in leaves and roots. The interaction ofM. truncatulawith the bacterial symbiontSinorhizobium melilotiis characterized by the formation of root nodules that fix atmospheric nitrogen. Although nodule numbers were slightly reduced at an early stage of the infection inEFR-Medicagowhen compared to control lines, nodulation was similar in all lines at later stages. Furthermore, nodule colonization by rhizobia, and nitrogen fixation were not compromised byEFRexpression. Importantly, theM. truncatulalines expressingEFRwere substantially more resistant to the root bacterial pathogenRalstonia solanacearum. Our data suggest that the transfer of EFR toM. truncatuladoes not impede root nodule symbiosis, but has a positive impact on disease resistance against a bacterial pathogen. In addition, our results indicate thatRhizobiumcan either avoid PAMP recognition during the infection process, or is able to actively suppress immune signaling.

Significance Statement

Crop engineering helps reducing the economic and environmental costs of plant disease. The genetic transfer of immune receptors across plant species is a promising biotechnological approach to increase disease resistance. Surface-localized pattern-recognition receptors (PRRs), which detect conserved characteristic microbial features, are functional in heterologous taxonomically-diverse plant species, and confer broad-spectrum disease resistance. It was unclear whether PRR transfer negatively impacts the association of the recipient plants with symbiotic microbes. Here, we show that a legume engineered with a novel PRR recognizing a conserved bacterial protein becomes more resistant to an important bacterial pathogen without significant impact on nitrogen-fixing symbiosis with rhizobia. This finding is of particular relevance as attempts to transfer this important symbiosis into non-legume plants are ongoing.
Customer orientation as a psychological construct: evidence from Indian B-B salespeople
Authors: Johlke Mark C. , Iyer Rajesh
Published: August 2017

Purpose

The purpose of this paper is to extend Zablahet al.’s (2012) findings regarding the proper way to treat customer orientation (CO) to the study of CO among B-B salespeople in one of the most important emerging economies, India.

Design/methodology/approach

The authors of this study hired a professional market research firm based in Chennai, a large metropolitan city in Southern India, to manage data collection. The authors used a competing models approach to test the relationship between constructs.

Findings

CO among frontline employees operating in one of the largest emerging economies is best treated as a psychological construct that is both directly and indirectly related to performance via its ability to reduce stress and improve engagement. This finding strengthens the view of CO as a universal human work value and, more broadly, that such values operating across different cultural setting do exist. In addition, external customer mindset appears to offer a superior means to measure CO than does the widely used CO component of the SOCO scale. This conclusion is based not only upon the fact that it conceptually corresponds with the psychological nature of CO, but also that in this initial examination it exhibits a greater ability to explain employee job performance.

Originality/value

Managers who are able to screen and hire employees with greater CO work values should experience improved performance outcomes and also less customer ambiguity and greater satisfaction among their frontline employees. Since CO proscribes the proper way to deal with customers, greater levels of CO beliefs would counteract customer ambiguity among frontline employees operating in any environment. Accordingly, when filling frontline positions, managers should actively seek out employees who earnestly embrace the role of taking care of customers. Managers are advised to not only emphasize on salespeople whose foremost role is to take care of their customers but also to find ways to familiarize them with their products and to provide them with information regarding customer characteristics such as their background, the relationship history (especially past service and product failures), and unique preferences.
Rosarium – a text encoding project curating popular writing on roses online
Authors: Tryon Julia Rachel
Published: August 2017

Purpose

The aim of this paper is to describe the Rosarium Project which is currently curating nonfiction materials about the genus Rosa written at the turn of the twentieth century and published in popular American periodicals. This is achieved by encoding the texts following the guidelines set forth by the Text Encoding Initiative Consortium (TEI).

Design/methodology/approach

This paper explains what text encoding is and why following the guidelines set forth by the TEI Consortium was the best choice for the Rosarium Project. It then goes on to outline the workflow and choices made by the principal researcher which are needed to move the project steadily forward.

Findings

The principal researcher on the Rosarium Project has found that encoding with the TEI was easy to learn and fun to do, as well as intellectually stimulating. Librarians should find text-encoding projects of their own specialist subjects equally doable.

Originality/value

The Rosarium Project is unique, in that it is curating early twentieth century articles on the subject of roses that appeared in popular magazines. These materials are hidden away in online repositories and libraries worldwide. This project is of value, in that it provides primary sources to researchers in areas of popular culture, horticulture and garden history and also acts as an example of what librarians can contribute to the Digital Humanities.