mode Cracks in the well-plastered façade of the Nordic model: reflections on inequalities in housing and mobility in (post-)coronavirus pandemic Sweden. By ezproxy.scu.edu.au Published On :: Mon, 01 Aug 2022 00:00:00 -0400 Children's Geographies; 08/01/2022(AN 158427721); ISSN: 14733285Academic Search Premier Full Article SWEDEN COVID-19 pandemic HOUSING discrimination RACIAL inequality PUBLIC transit YOUNG adults
mode Introduction: Modernity, Schooling and Childhood in India: Trajectories of Exclusion. By ezproxy.scu.edu.au Published On :: Thu, 01 Dec 2022 00:00:00 -0500 Children's Geographies; 12/01/2022(AN 160715515); ISSN: 14733285Academic Search Premier Full Article INDIA MODERNITY CHILDREN'S rights RIGHT to education SUBALTERN
mode Special issue: modernity, schooling, and childhood in India: trajectories of exclusion. By ezproxy.scu.edu.au Published On :: Thu, 01 Dec 2022 00:00:00 -0500 Children's Geographies; 12/01/2022(AN 160715517); ISSN: 14733285Academic Search Premier Full Article SOCIAL sciences education EDUCATIONAL sociology MODERNITY DEVELOPMENTAL psychology POLITICAL participation
mode Application of the COM-B model to the correlates of children's outdoor playing and the potential role of digital interventions: a systematic literature review. By ezproxy.scu.edu.au Published On :: Thu, 01 Jun 2023 00:00:00 -0400 Children's Geographies; 06/01/2023(AN 164286253); ISSN: 14733285Academic Search Premier Full Article CHILD behavior DIGITAL technology PERFORMANCE in children
mode Multi-dimensional lens to article 12 of the UNCRC: a model to enhance children's participation. By ezproxy.scu.edu.au Published On :: Thu, 01 Jun 2023 00:00:00 -0400 Children's Geographies; 06/01/2023(AN 164286248); ISSN: 14733285Academic Search Premier Full Article BRAZIL PARTICIPATION CONVENTION on the Rights of the Child
mode Modelling geographic access and school catchment areas across public primary schools to support subnational planning in Kenya. By ezproxy.scu.edu.au Published On :: Sun, 01 Oct 2023 00:00:00 -0400 Children's Geographies; 10/01/2023(AN 173035616); ISSN: 14733285Academic Search Premier Full Article KENYA SUSTAINABLE Development Goals (United Nations) TRAVEL time (Traffic engineering) PRIMARY schools PUBLIC spaces PUBLIC schools COST allocation
mode Identifying clientelism in orphanages: a conceptual model. By ezproxy.scu.edu.au Published On :: Thu, 01 Aug 2024 00:00:00 -0400 Children's Geographies; 08/01/2024(AN 178911406); ISSN: 14733285Academic Search Premier Full Article PARENTAL death SOCIAL networks ORPHANAGES PATRONAGE CONCEPTUAL models
mode Historicising the perpetrators of sexual violence: global perspectives from the modern world By ifp.nyu.edu Published On :: Fri, 25 Oct 2024 21:17:53 +0000 Volume 32, Issue 7, December 2023. Read the full article › The post Historicising the perpetrators of sexual violence: global perspectives from the modern world was curated by information for practice. Full Article History
mode Considering a Unified Model of Artificial Intelligence Enhanced Social Work: A Systematic Review By ifp.nyu.edu Published On :: Sat, 02 Nov 2024 15:24:39 +0000 Abstract Social work, as a human rights–based profession, is globally recognized as a profession committed to enhancing human well-being and helping meet the basic needs of all people, with a particular focus on those who are marginalized vulnerable, oppressed, or living in poverty. Artificial intelligence (AI), a sub-discipline of computer science, focuses on developing computers […] The post Considering a Unified Model of Artificial Intelligence Enhanced Social Work: A Systematic Review was curated by information for practice. Full Article Meta-analyses - Systematic Reviews
mode Potential Schizophrenia Medications Point to New Disease Model By ifp.nyu.edu Published On :: Mon, 07 Oct 2024 20:07:41 +0000 The post Potential Schizophrenia Medications Point to New Disease Model was curated by information for practice. Full Article Infographics
mode Co-knowledge production linking science, communities and public policy under deep uncertainty in a modern risk society in Japan By ifp.nyu.edu Published On :: Mon, 04 Nov 2024 04:56:19 +0000 The post Co-knowledge production linking science, communities and public policy under deep uncertainty in a modern risk society in Japan was curated by information for practice. Full Article Grey Literature
mode A Modern Extension Expands a Mid-Century House in Winchester By design-milk.com Published On :: Tue, 22 Oct 2024 16:00:14 +0000 The Seventies House by AR Design Studio blends 1970s charm with modern design in Winchester, UK, creating a seamless indoor-outdoor experience. Full Article Architecture Main addition additions AR Design Studio England extension floor-to-ceiling windows house indoor outdoor rear extension residential United Kingdom
mode A Loss Cycle of Burnout Symptoms and Reduced Coping Self-Efficacy: A Latent Change Score Modelling Approach By ifp.nyu.edu Published On :: Sat, 02 Nov 2024 15:59:30 +0000 Chronic Stress, Volume 8, Issue , January-December 2024. Police officers are frequently faced with chronic and acute stressors, such as excessive workload, organizational stressors and emotionally charged reports. This study aims to examine the relationship between a form of chronic strain (ie, burnout symptoms) and a resource (ie, coping self-efficacy) in a sample of Dutch […] The post A Loss Cycle of Burnout Symptoms and Reduced Coping Self-Efficacy: A Latent Change Score Modelling Approach was curated by information for practice. Full Article Open Access Journal Articles
mode Staff Verification Engineer, CPU Modelling, Experienced Professionals, Bangalore, India, Software Engineering By careers.peopleclick.com Published On :: Wednesday, July 29, 2020 6:03:46 PM EDT IntroductionArm architects the pervasive intelligence that is transforming our daily experience. Arm-based chips and device architectures orchestrate the performance of the technology that makes modern life possible.Arm designs the technology which is at the heart of advanced digital products, from wireless, networking and consumer entertainment solutions to imaging, automotive, security and storage devices. Arm improves people’s lives by enabling the intelligence in affordable, easy-to-use electronic products that transform the way we live and work. We work in partnership with a global network of leading technology companies which are using our smart low-power technology. Together we are shaping the future of a better world.Today, We are well recognized as the market leader in the CPU and System IP industry and this has been achieved by consistently delivering reliable and high-quality IP products. The cost of design and manufacturing and that warrants “right first time” approach for all IP and System products by our partners. Time-to-market is critical for our partners to deal with fierce competition in the marketplace, being first would enable them to get premium value from the end products. In this context, Design Verification of CPU IPs is a big challenge requiring an engineering skillset that is both broad and deep. Full Article
mode CPU Performance –Sr Principal Modeling Architect, Experienced Professionals, Austin (TX), USA, Hardware Engineering By careers.peopleclick.com Published On :: Friday, January 17, 2020 7:07:41 PM EST About this roleIf you are a technical lead with engineering expertise in CPU microarchitecture, performance-model development, performance analysis, or workload analysis, we would like to talk with you about joining Arm’s highly successful CPU performance architecture team based in Austin. Our team plays a major role in crafting our next-generation Cortex-A class CPU designs and in enabling Arm partners to use our designs in world-class products. As a senior member of this expert team, you will own substantial and challenging performance projectsWhat types of projects will you accomplish?Collaborate with other members of the design team - primarily in Austin - to help design our next-generation CPU microarchitectureLend your expertise across all Performance sub-disciplines: microarchitecture and performance model development, microarchitectural performance analysis, RTL/performance-model correlation, workload analysis, and workload developmentEngage with key partners at an engineering level to understand their future performance requirements, performance sensitivities, and workload expectationsHelp develop the team and be a mentor to engineersInteract with customers and other third parties to successfully communicate complex technical ideas, and participate in internal and customer meetings Full Article
mode 2021 Graduate Modelling Engineer - Cambridge, Graduates, Cambridge, UK, Cambridge, UK, Software Engineering By careers.peopleclick.com Published On :: Monday, August 24, 2020 7:29:16 AM EDT We have an exciting opportunity for a graduate developer in the GPU modelling team, based in Cambridge. We work with software models which are state-of-the-art representations of our products. They are used by several teams within the company and are delivered externally to some of our partners.We develop in C++ in a UNIX environment. Working in the GPU modelling team, your role will primarily be to model the functional and performance aspects of our GPUs. You will be working with dedicated and talented people across the globe as part of our multi-site development projects. Your work will have a large impact on the design and quality of our GPUs and ultimately on the success of Arm.If you would like to shape the future of energy-efficient devices, this is the place to be! Full Article
mode Efficacy and Safety of Sustained-release Dexamphetamine in Patients With Moderate to Severe Cocaine Use Disorder By ifp.nyu.edu Published On :: Wed, 23 Oct 2024 18:39:05 +0000 The post Efficacy and Safety of Sustained-release Dexamphetamine in Patients With Moderate to Severe Cocaine Use Disorder was curated by information for practice. Full Article Clinical Trials
mode SIAN Design Generates Modern Fine Jewelry Using Algorithms By design-milk.com Published On :: Mon, 05 Aug 2024 16:00:27 +0000 Architects Antonia Frey-Vorhammer and Simon Vorhammer, of SIAN, design jewelry that mirrors their highly intricate + geometric projects. Full Article Main Style + Fashion Technology Antonia Frey-Vorhammer jewelry jewelry designer modern jewelry rings Sian Design Simon Vorhammer
mode One Size Does Not Fit All: Unraveling Item Response Process Heterogeneity Using the Mixture Dominance-Unfolding Model (MixDUM) By ifp.nyu.edu Published On :: Tue, 05 Nov 2024 04:09:24 +0000 Organizational Research Methods, Ahead of Print. When modeling responses to items measuring non-cognitive constructs that require introspection (e.g., personality, attitude), most studies have assumed that respondents follow the same item response process—either a dominance or an unfolding one. Nevertheless, the results are not equivocal, as some preliminary evidence suggests that some people use an unfolding […] The post One Size Does Not Fit All: Unraveling Item Response Process Heterogeneity Using the Mixture Dominance-Unfolding Model (MixDUM) was curated by information for practice. Full Article Journal Article Abstracts
mode Ethical leaders’ search for meaning: Ancient Confucian wisdom in Modern East Asia By ifp.nyu.edu Published On :: Tue, 05 Nov 2024 05:39:55 +0000 Culture &Psychology, Ahead of Print. In secular Western societies, individuals often embark on an autonomous quest for meaning in life, which, however, can lead to frustration. In contrast, many East Asian ethical leaders draw on age-old teachings to find fulfillment—an underexplored topic that merits further investigation. By analyzing ancient Confucian tenets and the discourses of […] The post Ethical leaders’ search for meaning: Ancient Confucian wisdom in Modern East Asia was curated by information for practice. Full Article Journal Article Abstracts
mode Kyano: A 1960s Athens Apartment Reimagined for Modern Living By design-milk.com Published On :: Thu, 31 Oct 2024 16:00:26 +0000 Space is around us transforms the Kyano apartment in Athens into a sleek, multifunctional space that blends history with contemporary design. Full Article Architecture Interior Design Main apartment Athens blue blue kitchen cobalt blue color color block colorblock colorful Greece interior design residential small living Space is around us
mode 2024 Best Modern Gifts to Splurge On By design-milk.com Published On :: Tue, 12 Nov 2024 16:00:43 +0000 Design Milk's latest 2024 holiday gift guide will give you enviable objects to splurge on a dearly beloved or special friend. Full Article Interior Design Lifestyle Main 2024 gift guide Carlo Scarpa Diptyque dOt East Fork East Fork Pottery Franca gift guide gift guides gifts holiday gift guide holiday gift guides Lobmeyr modern gifts Oswald Haerdtl Prada Reflections Copenhagen Sam Baron Sonia Delaunay Tivoli Tivoli Audio Unison Vetro Vero Wooj
mode 2024 Best Modern Gifts for Kids By design-milk.com Published On :: Tue, 05 Nov 2024 17:00:33 +0000 From imaginative play sets to museum-worthy crafts, these modern gift ideas promise wide-eyed wonder and endless fun for kids of all ages. Full Article Home Furnishings Lifestyle Main 2024 gift guide Areaware Avenlur basketball Chance Clixo dusen dusen gift guide gift guides Giiker hair clip holiday gift guide holiday gift guides Jenny Lemons kids kids toys Majo Ideas Mochi Kids Mushie night light Noble play house play kitchen puzzle toy Studio Eggi utility suit
mode The Runda Tables Are Entry-Level High Design for Modern Homes By design-milk.com Published On :: Mon, 11 Nov 2024 15:00:04 +0000 The Runda tables by Form Us With Love for Rareraw redefine modern design with adaptable, sustainable features that evolve alongside your home. Full Article Home Furnishings Main Form Us With Love furniture FUWL home furnishings metal Rareraw side table side tables table
mode 2024 Best Modern Gifts Under $100 By design-milk.com Published On :: Mon, 11 Nov 2024 16:00:16 +0000 From tabletop accessories to wall art to the rug beneath your feet, Design Milk has curated the perfect gift guide with ideas under $100. Full Article Home Furnishings Lifestyle Main 2024 gift guide 2024 holiday gift guide Aaron probyn Dorothy gift guide gift guides holiday gift guide holiday gift guides holiday gifts HOVE Iittala Light + Ladder Light and Ladder McClean Design Mud Australia Obakki Quiet Town Tortuga Forma Trevor Parker Zafferano
mode Remodeling Project by Marcus Coker By www.flickr.com Published On :: Thu, 18 Sep 2014 21:36:53 -0700 Marcus of All Trades posted a photo: Full Article
mode Do Ohio High Schools Need To Take A Closer Look At "Pay-to-Play"Model? By radio.wosu.org Published On :: Fri, 26 Feb 2016 21:28:12 +0000 It can costs kids and parents several hundred dollars to play a single sport in high school. Could there be big changes to the "pay-to-play" system in Ohio? Full Article
mode Strengthening the MSP portfolio: Navigating modern cybersecurity By www.retailtechnologyreview.com Published On :: By Marc Malafronte, director of sales, VIPRE Security Group.As cyberattacks increase in frequency and sophistication, businesses must prioritize cybersecurity as a critical investment area. Managed service providers (MSPs) are crucial in supporting organizations on their cybersecurity journey. Full Article Surveillance and Security Critical Issues Cyber Security
mode Penn GSE, the School District of Philadelphia, Foundations, Inc. and the Consortium for Policy Research in Education Partnering to Create an Innovative and Scalable College and Career Readiness Model for Students By www.newswise.com Published On :: Tue, 12 Nov 2024 11:30:27 EST The University of Pennsylvania Graduate School of Education (Penn GSE) has been awarded $3.5 million, part of a larger $8 million grant from Education Initiatives, to partner with the School District of Philadelphia (SDP) to launch The Academy at Penn, an innovative five-year, cohort-based college- and career-readiness model for high school students. Foundations, Inc. and the Consortium for Policy Research in Education (CPRE) were also awarded through the grant as part of the larger partnership. The close collaboration involves working together to design, implement, and evaluate the project. Full Article
mode Business Models and Lean Startup By www.newswise.com Published On :: Tue, 05 Nov 2024 09:25:59 EST Full Article
mode First national-scale groundwater model in Great Britain developed - British Geological Survey By news.google.com Published On :: Tue, 14 May 2024 10:50:37 GMT First national-scale groundwater model in Great Britain developed British Geological Survey Full Article
mode Seed layer formation by deposition of micro-crystallites on a revolving substrate: modeling of the effective linear elastic, piezoelectric, and dielectric coefficients By journals.iucr.org Published On :: The rotating substrate method of crystallite deposition is modeled, allowing computation of effective material coefficients of the layers resulting from the averaging. A worked numerical example particularized to 6mm ZnO is provided. Full Article text
mode Analytical models representing X-ray form factors of ions By journals.iucr.org Published On :: 2024-01-01 Parameters in analytical models for X-ray form factors of ions f0(s), based on the inverse Mott–Bethe formula involving a variable number of Gaussians, are determined for a wide range of published data sets {s, f0(s)}. The models reproduce the calculated form-factor values close to what is expected from a uniform statistical distribution with limits determined by their precision. For different ions associated with the same atom, the number of Gaussians in the models decreases with increasing net positive charge. Full Article text
mode Modelling dynamical 3D electron diffraction intensities. I. A scattering cluster algorithm By journals.iucr.org Published On :: 2024-01-25 Three-dimensional electron diffraction (3D-ED) is a powerful technique for crystallographic characterization of nanometre-sized crystals that are too small for X-ray diffraction. For accurate crystal structure refinement, however, it is important that the Bragg diffracted intensities are treated dynamically. Bloch wave simulations are often used in 3D-ED, but can be computationally expensive for large unit cell crystals due to the large number of diffracted beams. Proposed here is an alternative method, the `scattering cluster algorithm' (SCA), that replaces the eigen-decomposition operation in Bloch waves with a simpler matrix multiplication. The underlying principle of SCA is that the intensity of a given Bragg reflection is largely determined by intensity transfer (i.e. `scattering') from a cluster of neighbouring diffracted beams. However, the penalty for using matrix multiplication is that the sample must be divided into a series of thin slices and the diffracted beams calculated iteratively, similar to the multislice approach. Therefore, SCA is more suitable for thin specimens. The accuracy and speed of SCA are demonstrated on tri-isopropyl silane (TIPS) pentacene and rubrene, two exemplar organic materials with large unit cells. Full Article text
mode Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering By journals.iucr.org Published On :: 2024-01-25 The strong interaction of high-energy electrons with a crystal results in both dynamical elastic scattering and inelastic events, particularly phonon and plasmon excitation, which have relatively large cross sections. For accurate crystal structure refinement it is therefore important to uncover the impact of inelastic scattering on the Bragg beam intensities. Here a combined Bloch wave–Monte Carlo method is used to simulate phonon and plasmon scattering in crystals. The simulated thermal and plasmon diffuse scattering are consistent with experimental results. The simulations also confirm the empirical observation of a weaker unscattered beam intensity with increasing energy loss in the low-loss regime, while the Bragg-diffracted beam intensities do not change significantly. The beam intensities include the diffuse scattered background and have been normalized to adjust for the inelastic scattering cross section. It is speculated that the random azimuthal scattering angle during inelastic events transfers part of the unscattered beam intensity to the inner Bragg reflections. Inelastic scattering should not significantly influence crystal structure refinement, provided there are no artefacts from any background subtraction, since the relative intensity of the diffracted beams (which includes the diffuse scattering) remains approximately constant in the low energy loss regime. Full Article text
mode Automated selection of nanoparticle models for small-angle X-ray scattering data analysis using machine learning By journals.iucr.org Published On :: 2024-02-29 Small-angle X-ray scattering (SAXS) is widely used to analyze the shape and size of nanoparticles in solution. A multitude of models, describing the SAXS intensity resulting from nanoparticles of various shapes, have been developed by the scientific community and are used for data analysis. Choosing the optimal model is a crucial step in data analysis, which can be difficult and time-consuming, especially for non-expert users. An algorithm is proposed, based on machine learning, representation learning and SAXS-specific preprocessing methods, which instantly selects the nanoparticle model best suited to describe SAXS data. The different algorithms compared are trained and evaluated on a simulated database. This database includes 75 000 scattering spectra from nine nanoparticle models, and realistically simulates two distinct device configurations. It will be made freely available to serve as a basis of comparison for future work. Deploying a universal solution for automatic nanoparticle model selection is a challenge made more difficult by the diversity of SAXS instruments and their flexible settings. The poor transferability of classification rules learned on one device configuration to another is highlighted. It is shown that training on several device configurations enables the algorithm to be generalized, without degrading performance compared with configuration-specific training. Finally, the classification algorithm is evaluated on a real data set obtained by performing SAXS experiments on nanoparticles for each of the instrumental configurations, which have been characterized by transmission electron microscopy. This data set, although very limited, allows estimation of the transferability of the classification rules learned on simulated data to real data. Full Article text
mode Animations, videos and 3D models for teaching space-group symmetry By journals.iucr.org Published On :: Animations, videos and 3D models have been designed to visualize the effects of symmetry operators on selected cases of crystal structures, pointing out the relationship with the diagrams published in International Tables for Crystallography, Vol. A. Full Article text
mode Towards expansion of the MATTS data bank with heavier elements: the influence of the wavefunction basis set on the multipole model derived from the wavefunction By journals.iucr.org Published On :: This study examines the quality of charge density obtained by fitting the multipole model to wavefunctions in different basis sets. The complex analysis reveals that changing the basis set quality from double- to triple-zeta can notably improve the charge density related properties of a multipole model. Full Article text
mode Optimal operation guidelines for direct recovery of high-purity precursor from spent lithium-ion batteries: hybrid operation model of population balance equation and data-driven classifier By journals.iucr.org Published On :: This study proposes an operation optimization framework for impurity-free recycling of spent lithium-ion batteries. Using a hybrid population balance equation integrated with a data-driven condition classifier, the study firstly identifies the optimal batch and semi-batch operation conditions that significantly reduce the operation time with 100% purity of product; detailed guidelines are given for industrial applications. Full Article text
mode Animations, videos and 3D models for teaching space-group symmetry By journals.iucr.org Published On :: 2024-10-16 A series of animations, videos and 3D models that were developed, filmed or built to teach the symmetry properties of crystals are described. At first, these resources were designed for graduate students taking a basic crystallography course, coming from different careers, at the National Autonomous University of Mexico. However, the COVID-19 pandemic had the effect of accelerating the generation of didactic material. Besides our experience with postgraduate students, we have noted that 3D models attract the attention of children, and therefore we believe that these models are particularly useful for teaching children about the assembled arrangements of crystal structures. Full Article text
mode Influence of device configuration and noise on a machine learning predictor for the selection of nanoparticle small-angle X-ray scattering models By journals.iucr.org Published On :: 2024-09-23 Small-angle X-ray scattering (SAXS) is a widely used method for nanoparticle characterization. A common approach to analysing nanoparticles in solution by SAXS involves fitting the curve using a parametric model that relates real-space parameters, such as nanoparticle size and electron density, to intensity values in reciprocal space. Selecting the optimal model is a crucial step in terms of analysis quality and can be time-consuming and complex. Several studies have proposed effective methods, based on machine learning, to automate the model selection step. Deploying these methods in software intended for both researchers and industry raises several issues. The diversity of SAXS instrumentation requires assessment of the robustness of these methods on data from various machine configurations, involving significant variations in the q-space ranges and highly variable signal-to-noise ratios (SNR) from one data set to another. In the case of laboratory instrumentation, data acquisition can be time-consuming and there is no universal criterion for defining an optimal acquisition time. This paper presents an approach that revisits the nanoparticle model selection method proposed by Monge et al. [Acta Cryst. (2024), A80, 202–212], evaluating and enhancing its robustness on data from device configurations not seen during training, by expanding the data set used for training. The influence of SNR on predictor robustness is then assessed, improved, and used to propose a stopping criterion for optimizing the trade-off between exposure time and data quality. Full Article text
mode Open-source electrochemical cell for in situ X-ray absorption spectroscopy in transmission and fluorescence modes By journals.iucr.org Published On :: 2024-02-02 X-ray spectroscopy is a valuable technique for the study of many materials systems. Characterizing reactions in situ and operando can reveal complex reaction kinetics, which is crucial to understanding active site composition and reaction mechanisms. In this project, the design, fabrication and testing of an open-source and easy-to-fabricate electrochemical cell for in situ electrochemistry compatible with X-ray absorption spectroscopy in both transmission and fluorescence modes are accomplished via windows with large opening angles on both the upstream and downstream sides of the cell. Using a hobbyist computer numerical control machine and free 3D CAD software, anyone can make a reliable electrochemical cell using this design. Onion-like carbon nanoparticles, with a 1:3 iron-to-cobalt ratio, were drop-coated onto carbon paper for testing in situ X-ray absorption spectroscopy. Cyclic voltammetry of the carbon paper showed the expected behavior, with no increased ohmic drop, even in sandwiched cells. Chronoamperometry was used to apply 0.4 V versus reversible hydrogen electrode, with and without 15 min of oxygen purging to ensure that the electrochemical cell does not provide any artefacts due to gas purging. The XANES and EXAFS spectra showed no differences with and without oxygen, as expected at 0.4 V, without any artefacts due to gas purging. The development of this open-source electrochemical cell design allows for improved collection of in situ X-ray absorption spectroscopy data and enables researchers to perform both transmission and fluorescence simultaneously. It additionally addresses key practical considerations including gas purging, reduced ionic resistance and leak prevention. Full Article text
mode Quantifying bunch-mode influence on photon-counting detectors at SPring-8 By journals.iucr.org Published On :: 2024-02-16 Count-loss characteristics of photon-counting 2D detectors are demonstrated for eight bunch-modes at SPring-8 through Monte Carlo simulations. As an indicator, the effective maximum count rate was introduced to signify the X-ray intensity that the detector can count with a linearity of 1% or better after applying a count-loss correction in each bunch-mode. The effective maximum count rate is revealed to vary depending on the bunch-mode and the intrinsic dead time of the detectors, ranging from 0.012 to 0.916 Mcps (megacounts per second) for a 120 ns dead time, 0.009 to 0.807 Mcps for a 0.5 µs dead time and 0.020 to 0.273 Mcps for a 3 µs intrinsic detector dead time. Even with equal-interval bunch-modes at SPring-8, the effective maximum count rate does not exceed 1 Mcps pixel−1. In other words, to obtain data with a linearity better than 1%, the maximum intensity of X-rays entering the detector should be reduced to 1 Mcps pixel−1 or less, and, in some cases, even lower, depending on the bunch-mode. When applying count-loss correction using optimized dead times tailored to each bunch-mode, the effective maximum count rate exceeds the values above. However, differences in the effective maximum count rate due to bunch-modes persist. Users of photon-counting 2D detectors are encouraged to familiarize themselves with the count-loss characteristics dependent on bunch-mode, and to conduct experiments accordingly. In addition, when designing the time structure of bunch-modes at synchrotron radiation facilities, it is essential to take into account the impact on experiments using photon-counting 2D detectors. Full Article text
mode Modelling the power threshold and optimum thermal deformation of indirectly liquid-nitrogen cryo-cooled Si monochromators By journals.iucr.org Published On :: 2024-04-09 Maximizing the performance of crystal monochromators is a key aspect in the design of beamline optics for diffraction-limited synchrotron sources. Temperature and deformation of cryo-cooled crystals, illuminated by high-power beams of X-rays, can be estimated with a purely analytical model. The analysis is based on the thermal properties of cryo-cooled silicon crystals and the cooling geometry. Deformation amplitudes can be obtained, quickly and reliably. In this article the concept of threshold power conditions is introduced and defined analytically. The contribution of parameters such as liquid-nitrogen cooling efficiency, thermal contact conductance and interface contact area of the crystal with the cooling base is evaluated. The optimal crystal illumination and the base temperature are inferred, which help minimize the optics deformation. The model has been examined using finite-element analysis studies performed for several beamlines of the Diamond-II upgrade. Full Article text
mode Modes and model building in SHELXE By journals.iucr.org Published On :: 2024-01-01 Density modification is a standard step to provide a route for routine structure solution by any experimental phasing method, with single-wavelength or multi-wavelength anomalous diffraction being the most popular methods, as well as to extend fragments or incomplete models into a full solution. The effect of density modification on the starting maps from either source is illustrated in the case of SHELXE. The different modes in which the program can run are reviewed; these include less well known uses such as reading external phase values and weights or phase distributions encoded in Hendrickson–Lattman coefficients. Typically in SHELXE, initial phases are calculated from experimental data, from a partial model or map, or from a combination of both sources. The initial phase set is improved and extended by density modification and, if the resolution of the data and the type of structure permits, polyalanine tracing. As a feature to systematically eliminate model bias from phases derived from predicted models, the trace can be set to exclude the area occupied by the starting model. The trace now includes an extension into the gamma position or hydrophobic and aromatic side chains if a sequence is provided, which is performed in every tracing cycle. Once a correlation coefficient of over 30% between the structure factors calculated from such a trace and the native data indicates that the structure has been solved, the sequence is docked in all model-building cycles and side chains are fitted if the map supports it. The extensions to the tracing algorithm brought in to provide a complete model are discussed. The improvement in phasing performance is assessed using a set of tests. Full Article text
mode Structural determination and modeling of ciliary microtubules By journals.iucr.org Published On :: 2024-03-07 The axoneme, a microtubule-based array at the center of every cilium, has been the subject of structural investigations for decades, but only recent advances in cryo-EM and cryo-ET have allowed a molecular-level interpretation of the entire complex to be achieved. The unique properties of the nine doublet microtubules and central pair of singlet microtubules that form the axoneme, including the highly decorated tubulin lattice and the docking of massive axonemal complexes, provide opportunities and challenges for sample preparation, 3D reconstruction and atomic modeling. Here, the approaches used for cryo-EM and cryo-ET of axonemes are reviewed, while highlighting the unique opportunities provided by the latest generation of AI-guided tools that are transforming structural biology. Full Article text
mode Mononuclear binding and catalytic activity of europium(III) and gadolinium(III) at the active site of the model metalloenzyme phosphotriesterase By journals.iucr.org Published On :: 2024-03-21 Lanthanide ions have ideal chemical properties for catalysis, such as hard Lewis acidity, fast ligand-exchange kinetics, high coordination-number preferences and low geometric requirements for coordination. As a result, many small-molecule lanthanide catalysts have been described in the literature. Yet, despite the ability of enzymes to catalyse highly stereoselective reactions under gentle conditions, very few lanthanoenzymes have been investigated. In this work, the mononuclear binding of europium(III) and gadolinium(III) to the active site of a mutant of the model enzyme phosphotriesterase are described using X-ray crystallography at 1.78 and 1.61 Å resolution, respectively. It is also shown that despite coordinating a single non-natural metal cation, the PTE-R18 mutant is still able to maintain esterase activity. Full Article text
mode Robust and automatic beamstop shadow outlier rejection: combining crystallographic statistics with modern clustering under a semi-supervised learning strategy By journals.iucr.org Published On :: 2024-10-01 During the automatic processing of crystallographic diffraction experiments, beamstop shadows are often unaccounted for or only partially masked. As a result of this, outlier reflection intensities are integrated, which is a known issue. Traditional statistical diagnostics have only limited effectiveness in identifying these outliers, here termed Not-Excluded-unMasked-Outliers (NEMOs). The diagnostic tool AUSPEX allows visual inspection of NEMOs, where they form a typical pattern: clusters at the low-resolution end of the AUSPEX plots of intensities or amplitudes versus resolution. To automate NEMO detection, a new algorithm was developed by combining data statistics with a density-based clustering method. This approach demonstrates a promising performance in detecting NEMOs in merged data sets without disrupting existing data-reduction pipelines. Re-refinement results indicate that excluding the identified NEMOs can effectively enhance the quality of subsequent structure-determination steps. This method offers a prospective automated means to assess the efficacy of a beamstop mask, as well as highlighting the potential of modern pattern-recognition techniques for automating outlier exclusion during data processing, facilitating future adaptation to evolving experimental strategies. Full Article text
mode The success rate of processed predicted models in molecular replacement: implications for experimental phasing in the AlphaFold era By journals.iucr.org Published On :: 2024-10-03 The availability of highly accurate protein structure predictions from AlphaFold2 (AF2) and similar tools has hugely expanded the applicability of molecular replacement (MR) for crystal structure solution. Many structures can be solved routinely using raw models, structures processed to remove unreliable parts or models split into distinct structural units. There is therefore an open question around how many and which cases still require experimental phasing methods such as single-wavelength anomalous diffraction (SAD). Here, this question is addressed using a large set of PDB depositions that were solved by SAD. A large majority (87%) could be solved using unedited or minimally edited AF2 predictions. A further 18 (4%) yield straightforwardly to MR after splitting of the AF2 prediction using Slice'N'Dice, although different splitting methods succeeded on slightly different sets of cases. It is also found that further unique targets can be solved by alternative modelling approaches such as ESMFold (four cases), alternative MR approaches such as ARCIMBOLDO and AMPLE (two cases each), and multimeric model building with AlphaFold-Multimer or UniFold (three cases). Ultimately, only 12 cases, or 3% of the SAD-phased set, did not yield to any form of MR tested here, offering valuable hints as to the number and the characteristics of cases where experimental phasing remains essential for macromolecular structure solution. Full Article text
mode Solving protein structures by combining structure prediction, molecular replacement and direct-methods-aided model completion By journals.iucr.org Published On :: 2024-01-13 Highly accurate protein structure prediction can generate accurate models of protein and protein–protein complexes in X-ray crystallography. However, the question of how to make more effective use of predicted models for completing structure analysis, and which strategies should be employed for the more challenging cases such as multi-helical structures, multimeric structures and extremely large structures, both in the model preparation and in the completion steps, remains open for discussion. In this paper, a new strategy is proposed based on the framework of direct methods and dual-space iteration, which can greatly simplify the pre-processing steps of predicted models both in normal and in challenging cases. Following this strategy, full-length models or the conservative structural domains could be used directly as the starting model, and the phase error and the model bias between the starting model and the real structure would be modified in the direct-methods-based dual-space iteration. Many challenging cases (from CASP14) have been tested for the general applicability of this constructive strategy, and almost complete models have been generated with reasonable statistics. The hybrid strategy therefore provides a meaningful scheme for X-ray structure determination using a predicted model as the starting point. Full Article text