Equivalent Positions Research Articles

A Nonlinear Optical Switchable Sulfate of Ultrawide Bandgap

Nonlinear optical (NLO) switchable materials have attracted intense attention because of their promising applications in optoelectronic devices. However, previous studies are mainly limited to mole...

Comparison of transperineal ultrasound image guidance technique to transabdominal technique for prostate radiation therapy.

Ultrasound (US) guidance of the prostate has long been conducted using a transabdominal (TA) approach. More recently, a transperineal (TP) approach has been made available for image guidance. Our aim was to determine if both methods produced similar alignments within the same patients. We utilized two clinical US image guidance (IG) systems (Elekta Clarity and Best BAT). The B-mode Acquisition and Targeting USIG system is a bi-planar, so-called 2.5D USIG system, that is acquired TA. Clarity is a 3D US system that generates a volumetric 3D US data set and US-derived IG contours that are coregistered to the planning CT images. The probe is oriented in the sagittal plane against the perineum (TP). After positioning the patient for treatment using the TP USIG, we maintained the position defined by Clarity tracking and then acquired a TA-based USIG. The two US-based methods of localizing the prostate (TA vs TP) were compared via Bland-Altman (BA) statistical analysis to determine if there was alignment agreement between methods. The BA test for all 101 patients, 2093 fractions resulted in 95% confidence intervals (upper and lower limits of the BA test) of 0.6mm in LR, 0.9mm in AP and 1.0mm in SI. The bias between the two systems was calculated as 0.03, 0.02, and 0.03mm in LR, AP, and SI. Both systems resulted in statistically equivalent targeting positions for the prostate. Because of the unique intrafraction, real-time motion tracking capability of the TP system, this solution represents a unique extension to the previously reported clinical benefits of a TA approach by providing assurance of the prostate remaining in the treatment field during beam-on.

Structures of the SARS-CoV-2 nucleocapsid and their perspectives for drug design.

COVID-19, caused by SARS-CoV-2, has resulted in severe and unprecedented economic and social disruptions in the world. Nucleocapsid (N) protein, which is the major structural component of the virion and is involved in viral replication, assembly and immune regulation, plays key roles in the viral life cycle. Here, we solved the crystal structures of the N- and C-terminal domains (N-NTD and N-CTD) of SARS-CoV-2 N protein, at 1.8 and 1.5Å resolution, respectively. Both structures show conserved features from other CoV N proteins. The binding sites targeted by small molecules against HCoV-OC43 and MERS-CoV, which inhibit viral infection by blocking the RNA-binding activity or normal oligomerization of N protein, are relatively conserved in our structure, indicating N protein is a promising drug target. In addition, certain areas of N-NTD and N-CTD display distinct charge distribution patterns in SARS-CoV-2, which may alter the RNA-binding modes. The specific antigenic characteristics are critical for developing specific immune-based rapid diagnostic tests. Our structural information can aid in the discovery and development of antiviral inhibitors against SARS-CoV-2 in the future.

Reverse genetics reveals contrary effects of two Rdl-homologous GABA receptors of Helicoverpa armigera on the toxicity of cyclodiene insecticides

The resistance to dieldrin gene (Rdl) encodes a subunit of the insect γ-amino butyric acid (GABA) receptor, and the encoded Rdl subunit is a major target site for cyclodiene and phenylpyrazole insecticides. Since the substitution of a single amino acid (Ala to Ser/Gly at position 302) of the Drosophila melanogaster Rdl gene was first identified to confer high level resistance to dieldrin, mutations at the equivalent positions have been reported to confer resistance to dieldrin and/or fipronil in a wide range of different insects. In the cotton bollworm Helicoverpa armigera, there are two Rdl homologs (HaRdl-1 and HaRdl-2) in close proximity on the Z chromosome, which as wild-type sequences, encode alanine and serine respectively at amino acid position 302. In the present study, we used the CRISPR/Cas9 gene editing approach to knock out HaRdl-1 and HaRdl-2 and establish two homozygous knockout strains (ΔRdl-1 and ΔRdl-2). The ΔRdl-1 strain showed low levels of resistance (8.0- to 9.3-fold) to three cyclodiene insecticides (endosulfan, aldrin and dieldrin) compared with the background SCD strain. In contrast, toxicity of the three cyclodiene insecticides to the ΔRdl-2 strain increased significantly (3.6- to 6.3-fold) when compared with the SCD strain. Genetic analysis indicated the obtained resistance to endosulfan and dieldrin in the ΔRdl-1 strain was sex-linked, which is consistent with the fact that HaRdl-1 locus is located on the Z chromosome. The above results demonstrate that both HaRdl-1 and HaRdl-2 are important determinants for the susceptibility of H. armigera SCD strain to the three cyclodiene insecticides, but have opposite effects. It was also found that HaRdl-1 and HaRdl-2 are involved, to some extent, in mediating sensitivity of H. armigera to avermectin and fipronil respectively. We speculate that the HaRdl-1 and HaRdl-2 subunits have different pharmacological properties, which contribute to the differential sensitivities of H. armigera to the tested cyclodienes and other insecticides.

Predicting the Impact of COVID-19 on Australian Universities

This article explores the impact of the novel coronavirus (COVID-19) upon Australia’s education industry with a particular focus on universities. With the high dependence that the revenue structures of Australian universities have on international student tuition fees, they are particularly prone to the economic challenges presented by COVID-19. As such, this study considers the impact to total Australian university revenue and employment caused by the significant decline in the number of international students continuing their studies in Australia during the current pandemic. We use a linear regression model calculated from data published by the Australian Government’s Department of Education, Skills, and Employment (DESE) to predict the impact of COVID-19 on total Australian university revenue, the number of international student enrolments in Australian universities, and the number of full-time equivalent (FTE) positions at Australian universities. Our results have implications for both policy makers and university decision makers, who should consider the need for revenue diversification in order to reduce the risk exposure of Australian universities.

UK trading patterns within and between regions in the automotive sector—A network analysis

AbstractThis study provides an analysis of the UK's role in the automotive sector, focusing on the trading relationship of the UK within and between regions. It additionally provides an examination of the countries that hold equivalent trading positions to the UK in various segments of the automotive sector. The results indicate a high level of integration with Europe & Central Asia; outside the region, there appears to be a trend towards sourcing inputs from East Asia & Pacific, along with the Middle East & North Africa acting as an export destination. The equivalence analysis results provide a set of nations that could reposition themselves to gain from the UK's departure from the European Union. Amongst them are traditional key European players in the sector, along with Eastern European nations, which have been developing key strengths within the sector in recent years.

Derived crystal structure of martensitic materials by solid-solid phase transformation.

A mathematical description of crystal structure is proposed consisting of two parts: the underlying translational periodicity and the distinct atomic positions up to the symmetry operations in the unit cell, consistent with the International Tables for Crystallography. By the Cauchy-Born hypothesis, such a description can be integrated with the theory of continuum mechanics to calculate a derived crystal structure produced by solid-solid phase transformation. In addition, the expressions for the orientation relationship between the parent lattice and the derived lattice are generalized. The derived structure rationalizes the lattice parameters and the general equivalent atomic positions that assist the indexing process of X-ray diffraction analysis for low-symmetry martensitic materials undergoing phase transformation. The analysis is demonstrated in a CuAlMn shape memory alloy. From its austenite phase (L21 face-centered cubic structure), it is identified that the derived martensitic structure has orthorhombic symmetry Pmmn with the derived lattice parameters ad = 4.36491, bd = 5.40865 and cd = 4.2402 Å, by which the complicated X-ray Laue diffraction pattern can be well indexed, and the orientation relationship can be verified.

Outnumbered yet needed: The Lung Cancer Nurse Specialist.

Outnumbered yet needed: The Lung Cancer Nurse Specialist.

Effects of crystal chemistry and local random fields on relaxor and piezoelectric behavior of lead-oxide perovskites

Random electric fields caused by the disordered distribution of heterovalent cations over the equivalent crystallographic positions are often considered to be the main reason of the relaxor behavior and the associated giant electromechanical response. Some models relate the development of the relaxor state to the crystal chemical properties of the constituent ions. In this work the functions of random fields and ferroactive cations are compared in perovskite solid solutions in the desirable for technological applications composition range of morphotropic phase boundary. The crystal structure, dielectric and ferroelectric properties, piezoelectric effect and electrostriction are investigated in technologically important ceramic solid solutions PbzBa1−z(Mg1/3Nb2/3)m(Zn1/3Nb2/3)y(Ni1/3Nb2/3)nTixO3 with substitutions in A (Pb2+ by Ba2+)- and B (Ti4+ by [B2+1/3Nb5+2/3]4+) perovskite sublattices. Two composition sections of the system are designed; in both of them the concentration of ferroactive ions, Pb2+ and Ti4+, respectively, varies within the same range of 15%, but the strength of quenched random electric fields changes significantly only in B-substituted ceramics. Similar behavior is found in both sections, including the same sequence of structural phase transitions and transformations from normal ferroelectric to relaxor state and similar evolution of properties with concentration. The results clearly demonstrate that the role of crystal chemical factors in the development of relaxor behavior and electromechanical performance of lead-oxide materials is not less important than that of quenched random fields. The mechanisms of the observed behavior are discussed in the frame of existing theoretical models.

Effect of Temperature on the Formation of Stable and Metastable Aluminide Phases in Al‒Zr‒Nb Alloys

The conditions of the formation of stable and metastable aluminides Aln(Zr1 – xNbx) formed during the crystallization of superheated melts of the Al‒Zr‒Nb system are considered. Upon a close zirconium content in the alloys of 0.23–0.25 at %, the niobium content varies from 0.05 to 0.21 at %. Alloys are prepared in a resistance furnace at a temperature of 1230°C in an argon atmosphere in graphite crucibles. The alloys are cast into a bronze mold; the cooling rate is estimated as 200°C/s. The structural features, distribution, and morphology; the composition of matrix, dendritic cells, and aluminides; and the structural type of aluminides in the alloys are studied using scanning electron and optical microscopy, X-ray diffraction, and inductively coupled plasma atomic emission spectroscopy. It is shown that the growth forms of stable aluminides (D023 structural type) change from faceted to dendritic and primary metastable aluminides (L12 structural type) begin to form; in the process of the Al‒Zr‒Nb melt, overheating was 360–365°C above the liquidus temperature. Exclusively metastable aluminides with both polyhedral and dendritic growth forms are formed in the Al‒Zr‒Nb alloys when the overheating of their melt is 390–395°C (as well as at higher overheating) above the liquidus temperature. The near-peritectic niobium composition of the Al‒Zr‒Nb alloy and the zirconium content (more than seven times higher than peritectic) are crucial factors in the formation of a large fraction of metastable AlnZr aluminides having a cubic L12 structure. It is shown that, in accordance with the rules of isomorphism, Nb replaces Zr at equivalent positions of the aluminides crystal lattice. The intensity of isomorphism of the formed Al4(Zr0.79Nb0.21) aluminides increases with the increase in temperature of the melt overheating.

Effect of temperature on the formation of stable and metastable aluminide phases in the Al-Zr-Nb alloys

The paper considers formation conditions for stable and metastable aluminides Al n (Zr 1-x Nb x ) obtained in the crystallization of superheated Al—Zr—Nb melts. At the close zirconium content in the alloys of 0.23—0.25 at.%, the niobium content varied from 0.05 to 0.21 at.%. Alloys were prepared in a resistance furnace at 1230 °C in an argon atmosphere in graphite crucibles. Alloys were cast into a bronze mold where the cooling rate was estimated at 200 °C per second. The structural features, distribution pattern, morphology, the composition of the matrix, dendritic cells and aluminides, as well as the structural type of intermetallics in the investigated alloys were studied using scanning electron and optical microscopy, X -ray phase analysis, X -ray diffraction analysis, electron microprobe analysis including inductively coupled plasma atomic emission spectroscopy. It was shown that the growth forms of stable aluminides (D0 23 structural type) change from the faceted to dendritic one, and primary metastable aluminides ( L 1 2 structural type) begin to form during the Al—Zr—Nb melt overheating at 360—365 °C above the liquidus temperature. Only metastable aluminides with both polyhedral and dendritic growth forms are formed in the alloys when overheated by 390 —395 °C and higher. The near-peritectic niobium composition of the Al—Zr—Nb alloy (at the zirconium content more than seven times higher than the peritectic one) are crucial factors in the formation of a large fraction of metastable Al n Zr aluminides having a cubic L 1 2 structure. It was shown that, in accordance with isomorphism rules, Nb replaces Zr at equivalent positions of the crystal lattice of aluminides. The intensity of isomorphism of the Al 4 (Zr 0.79 Nb 0.21 ) intermetallics formed increases with the increasing melt overheating temperature.

Characterizing the Thermodynamic Stability of the Holliday Junction Through Spectroscopic Techniques

The Holliday junction is a four‐way DNA structure formed during the process of double strand break repair and DNA recombination in meiosis. Branch migration of the junction is a vital molecular process for the transfer of genetic information from parents to offspring. Understanding this process relative to base pair composition can provide a better picture of the overall structure of the junction and its connection to short inverted repeats that have been linked to chromosome instability. We used a fluorescent nucleoside analog, 4‐amino‐6methyl‐8‐(2‐deoxy‐beta‐d‐ribofuranosyl)‐7(8H)‐pteridone (6‐MAP), to obtain site‐specific information about the melting process, through incorporation of the probe at distinct sites throughout a 34 bp immobile junction. Under our conditions, the junction primarily adopts a conformation where the arms stack co‐axially on each other. We have examined the stability of the junction arms by incorporating the probe at equivalent positions on each arm. From these measurements we have found that the junction follows a 'pseudo‐duplex' model of denaturation, in which one of the coaxially stacked pair of arms melts at a lower temperature relative to the other. Our results also point to a sequential melting pattern in which positions at the end of the arms and the center destabilize before the interior of the arms. The relative proximity to the junction center appears to be one of the factors affecting stability. Our current research investigates how sequence homology influences the stability of the junction, specifically whether the thermodynamic characteristics of an immobile junction are predictive for a mobile one. We have developed a mobile junction with 10‐bp homology in the central region. Previous research by (Voth A.R., Hays F.A., Ho P.S. (2007) Directing macromolecular conformation through halogen bonds. Proc. Natl. Acad. Sci. USA.; 104:6188–6193. doi: 10.1073/pnas.0610531104) has suggested that macromolecular conformations can be directed through the use of halogen bonds. Specific incorporation of brominated uracils in the sequence of two DNA strands of a mobile Holliday junction was shown to bias the structure to a single conformation in crystallographic experiments. Combined spectroscopic data from both the immobile and mobile junction will inform coarse‐grained modeling of the Holliday junction. Our experimental data combined with computational modeling furthers our current understanding of this DNA structure as it relates to branch migration and exchange of genetic information.

Fostering Partnerships with the Safety Net: An Evaluation of Kaiser Permanente's Community Ambassador Program in the Mid-Atlantic States.

Kaiser Permanente (KP) Mid-Atlantic States has partnered with communities in its service area since 2011 to provide health services to underserved individuals. As part of KP's Community Benefit investment, the Community Ambassador Program places KP advanced-practice clinicians in safety-net clinics to share best practices and to improve access and quality of care. To report program outcomes and disseminate lessons learned. Using data from participating clinics, we retrospectively evaluated the program and estimated Community Ambassadors' contributions to clinic capacity, patient access, evidence-based care, and clinical quality measures. Furthermore, we conducted 29 semistructured phone interviews with stakeholders. Questions focused on program benefits, challenges, learning, and sustainability. From 2013 to 2017, Community Ambassadors filled up to 32.8 full-time equivalent positions and conducted 294,436 patient encounters in 19 clinics. In certain years and for subsets of clinics, Community Ambassadors performed above average on 2 high-priority quality measures: Cervical cancer screening for women aged 21 to 64 years and diabetes (blood glucose) control. Interviews with 15 Community Ambassadors, 15 health centers leaders, and 7 KP Mid-Atlantic States staff members revealed that Community Ambassadors improved patient access, clinic capacity, and care quality. Ambassadors also exported KP best practices and supported KP's community relations. Challenges included patient acuity, clinic resources, staff turnover, and long-term sustainability. The Community Ambassador Program achieved its goals and had clear benefits, offering a model for large health care systems wanting to collaborate with community-based clinics. Careful planning is needed to ensure that positive results are sustained.

Experimental Evidence for the Incorporation of Two Metals at Equivalent Lattice Positions in Mixed-Metal Metal-Organic Frameworks.

Metal–organic frameworks containing multiple metals distributed over crystallographically equivalent framework positions (mixed‐metal MOFs) represent an interesting class of materials, since the close vicinity of isolated metal centers often gives rise to synergistic effects. However, appropriate characterization techniques for detailed investigations of these mixed‐metal metal–organic framework materials, particularly addressing the distribution of metals within the lattice, are rarely available. The synthesis of mixed‐metal FeCuBTC materials in direct syntheses proved to be difficult and only a thorough characterization using various techniques, like powder X‐ray diffraction, X‐ray absorption spectroscopy and electron paramagnetic resonance spectroscopy, unambiguously evidenced the formation of a mixed‐metal FeCuBTC material with HKUST‐1 structure, which contained bimetallic Fe−Cu paddlewheels as well as monometallic Cu−Cu and Fe−Fe units under optimized synthesis conditions. The in‐depth characterization showed that other synthetic procedures led to impurities, which contained the majority of the applied iron and were impossible or difficult to identify using solely standard characterization techniques. Therefore, this study shows the necessity to characterize mixed‐metal MOFs extensively to unambiguously prove the incorporation of both metals at the desired positions. The controlled positioning of metal centers in mixed‐metal metal–organic framework materials and the thorough characterization thereof is particularly important to derive structure–property or structure–activity correlations.

Observation of symmetry breaking in photoalignment-induced periodic 3D LC structures

Abstract We report on the optical analysis of 3D periodic LC nematic structures, using crossed-polarizer transmission microscopy with oblique illumination. The structure is developed in a cell with orthogonally arranged top and bottom photoaligned periodic micro-patterns. We demonstrate experimentally that two unit cell director configurations can be formed in the device. The size of the unit cell is two times larger than the period of the micropattern because symmetry breaking allows avoiding disclinations lines in the bulk of the liquid crystal. As a result, each unit cell can be located in four equivalent positions. Q-tensor finite element simulations show that the two unit cells have different elastic energy. Oblique illumination transmission experiments are in good agreement with numerical simulations. The observed structures are interesting for optical manipulation purposes, liquid crystal based lasing, geometric phase implementation and many other photonics applications.

How Exhausting!? Emotion Crossover in Organizational Social Networks

AbstractDoes emotional exhaustion cross over between employees? Departing from the traditional within‐person view, we draw on the crossover model to argue and test an interpersonal model of emotional exhaustion. We conducted a sociocentric social network study in a U.S. construction company and found that employees had similar levels of emotional exhaustion to co‐workers with whom they had interaction and advice ties and structurally equivalent network positions, but that they did not have similar emotional exhaustion to friends or supervisors. We advance scholarly understanding of emotion crossover by theorizing and simultaneously testing important organizationally structured patterns of interaction and transfer previously unexamined, examined only in isolation or examined in a piecemeal manner. Our results highlight the importance of exploring the influence of structural and relational patterns embedded in the organization’s formal and informal structures and provide a theoretical and methodological platform to advance our understanding of crossover, emotional contagion and important outcomes at work.

The State of the Job Market for Pathologists: Evidence From the College of American Pathologists Practice Leader Survey.

Disagreement exists within the pathology community about the status of the job market for pathologists. Although many agree that jobs in pathology were harder to come by earlier this decade, recent evidence suggests improvement is occurring. To assess the state of the job market for pathologists. We analyzed data from the 2018 College of American Pathologists Practice Leader Survey. This survey contains data from 253 practice leaders on practices' hiring (and retrenchments) in 2017, the skills and level of experience being sought, success in filling those positions, and expectations for hiring in the next 3 years. Among the surveyed practice leaders, 115 (45.5%) sought to hire at least 1 pathologist in 2017, and together tried to fill 246 full-time equivalent positions that year, of which 93.5 full-time equivalents (38%) were newly created. This hiring was not limited to larger, academic-based practices, but also occurred among smaller practices and practices based in nonacademic hospitals, independent laboratories, and other settings. Although some practices retrenched (60 full-time equivalents in 2017), the net increase was a healthy 187 full-time equivalents. Practices most frequently sought pathologists who had at least 2 years of experience, but the level of experience identified with the "optimal" candidate varied by desired areas of subspecialty expertise. Practice leaders also reported expected growth in hiring, with the number of positions they hope to fill in the next 3 years exceeding those vacated by retirement. Our findings support the proposition that the demand for pathologists is strong, at least at the current time.

Theoretical investigation of the deformation stability and thermostability of carbon diamond-like phases

In this work, first-principle calculations of the mechanical and thermal stability of diamond-like LA3 and LA5 phases with equivalent atomic positions were carried out. It was established that these phases can be stable under uniaxial deformations in the pressure range from -62 to 85 GPa. The calculations also showed that LA3 and LA5 phases should be stable at a temperature of 500 K and normal pressure.

The introduction of functional side groups and the application of the mixed-linker concept in divalent MIL-53(Ni) materials.

Metal-organic framework materials with functional side groups are commonly used for various purposes like post-synthetic modification reactions or the tuning of pore geometries. Additionally, the mixed-linker concept, in which different linkers are statistically distributed over equivalent lattice positions, is a versatile approach to adjust the number of functional groups within the framework. However, neither functional side groups nor the mixed-linker approach have been used in MIL-53 materials with divalent metal ions yet. In the present work, we report on the synthesis of MIL-53(Ni)-Br(100), which contains only 2-bromoterephthalate as a linker molecule, and mixed-linker MIL-53(Ni)-Br(50) containing both terephthalate and 2-bromoterephthalate. These two materials represent the first functionalized and mixed-linker MIL-53 materials in combination with a divalent metal. Consequently, the possibilities to tailor the properties of the still rarely used divalent MIL-53 materials were expanded.

The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2

The organic-inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling-heating cycles over the temperature ranges 290-100-290 K. In the room-temperature phase (I), space group C2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinic X2/c(α,0,γ)0s superspace group (where X is ½, ½, 0, ½) with modulation wavevectors q = (0.2943, 0, 0.5640) and q = (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinic P{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.