Showing papers by "York University published in 2023"

Scattering in black hole backgrounds and higher-spin amplitudes. Part I

Abstract: A bstract The scattering of massless waves of helicity $$ \mid h\mid =0,\frac{1}{2},1 $$ ∣ h ∣ = 0 , 1 2 , 1 in Schwarzschild and Kerr backgrounds is revisited in the long-wavelength regime. Using a novel description of such backgrounds in terms of gravitating massive particles, we compute classical wave scattering in terms of 2 → 2 QFT amplitudes in flat space, to all orders in spin. The results are Newman-Penrose amplitudes which are in direct correspondence with solutions of the Regge-Wheeler/Teukolsky equation. By introducing a precise prescription for the point-particle limit, in Part I of this work we show how both agree for h = 0 at finite values of the scattering angle and arbitrary spin orientation. Associated classical observables such as the scattering cross sections, wave polarizations and time delay are studied at all orders in spin. The effect of the spin of the black hole on the polarization and helicity of the waves is found in agreement with previous analysis at linear order in spin. In the particular limit of small scattering angle, we argue that wave scattering admits a universal, point-particle description determined by the eikonal approximation. We show how our results recover the scattering eikonal phase with spin up to second post-Minkowskian order, and match it to the effective action of null geodesics in a Kerr background. Using this correspondence we derive classical observables such as polar and equatorial scattering angles. This study serves as a preceding analysis to Part II, where the Gravitational Wave ( h = 2) case will be studied in detail.

Mitochondrial protein import and UPRmt in skeletal muscle remodeling and adaptation

Abstract: The biogenesis of mitochondria requires the coordinated expression of the nuclear and the mitochondrial genomes. However, the vast majority of gene products within the organelle are encoded in the nucleus, synthesized in the cytosol, and imported into mitochondria via the protein import machinery, which permit the entry of proteins to expand the mitochondrial network. Once inside, proteins undergo a maturation and folding process brought about by enzymes comprising the unfolded protein response (UPRmt). Protein import and UPRmt activity must be synchronized and matched with mtDNA-encoded subunit synthesis for proper assembly of electron transport chain complexes to avoid proteotoxicity. This review discusses the functions of the import and UPRmt systems in mammalian skeletal muscle, as well as how exercise alters the equilibrium of these pathways in a time-dependent manner, leading to a new steady state of mitochondrial content resulting in enhanced oxidative capacity and improved muscle health.

Velocity reconstruction with the cosmic microwave background and galaxy surveys

Abstract: The kinetic Sunyaev Zel'dovich (kSZ) and moving lens effects, secondary contributions to the cosmic microwave background (CMB), carry significant cosmological information due to their dependence on the large-scale peculiar velocity field. Previous work identified a promising means of extracting this cosmological information using a set of quadratic estimators for the radial and transverse components of the velocity field. These estimators are based on the statistically anisotropic components of the cross-correlation between the CMB and a tracer of large scale structure, such as a galaxy redshift survey. In this work, we assess the challenges to the program of velocity reconstruction posed by various foregrounds and systematics in the CMB and galaxy surveys, as well as biases in the quadratic estimators. To do so, we further develop the quadratic estimator formalism and implement a numerical code for computing properly correlated spectra for all the components of the CMB (primary/secondary blackbody components and foregrounds) and a photometric redshift survey, with associated redshift errors, to allow for accurate forecasting. We create a simulation framework for generating realizations of properly correlated CMB maps and redshift binned galaxy number counts, assuming the underlying fields are Gaussian, and use this to validate a velocity reconstruction pipeline and assess map-based systematics such as masking. We highlight the most significant challenges for velocity reconstruction, which include biases associated with: modelling errors, characterization of redshift errors, and coarse graining of cosmological fields on our past light cone. Despite these challenges, the outlook for velocity reconstruction is quite optimistic, and we use our reconstruction pipeline to confirm that these techniques will be feasible with near-term CMB experiments and photometric galaxy redshift surveys.

Roles of Hydrogen Sulfide in Hypertension Development and Its Complications: What, So What, Now What

Abstract: Hypertension is a multicause health challenge, and hydrogen sulfide (H2S) is a multifunctional gasotransmitter. A critical pathologic role of endogenous H2S deficiency in the development of hypertension was established 15 years ago based on animal studies, setting the stage for examining the wide spectrum of cardiovascular effects and the underlying molecular and cellular mechanisms of H2S. We are also starting to gain a better understanding of the role of altered H2S metabolism in human hypertension. The purpose of this article is to examine our current understanding of the roles played by H2S in the development of hypertension in both animals and humans. Additionally, H2S-based antihypertension therapeutic strategies are reviewed. Is H2S at the root of hypertension and one of the solutions for the same? The probability is very high.

Insulin‐resistant female rat skeletal muscles display diacylglycerol‐mediated protein kinase C activation and inflammation without ceramide accumulation

Abstract: This study investigated the role of diacylglycerol (DAG)-mediated protein kinase C (PKC) activation, ceramide accumulation and inflammation in insulin-resistant female oxidative and glycolytic skeletal muscles induced by an obesogenic high-fat sucrose-enriched (HFS) diet. The HFS diet impaired insulin-stimulated AKTThr308 phosphorylation and glycogen synthesis, whereas rates of fatty acid oxidation and basal lactate production were significantly elevated in soleus (Sol), extensor digitorum longus (EDL) and epitrochlearis (Epit) muscles. Insulin resistance was accompanied by increases in triacylglycerol (TAG) and DAG contents in Sol and EDL, whereas in Epit muscles only TAG content and markers of inflammation were associated with HFS diet-induced insulin resistance. Analysis of membrane-bound/cytoplasmic PKC fractions revealed that the HFS diet promoted activation/translocation of PKCδ and θ isoforms in Sol, EDL and Epit muscles. However, none of these muscles displayed alterations in ceramide content in response to HFS feeding. This could be explained by a significant increase in Dgat2 mRNA expression in Sol, EDL and Epit muscles, which likely diverted most of the intramyocellular acyl-CoAs toward TAG synthesis instead of ceramides. Overall, this study helps elucidate the molecular mechanisms underlying insulin resistance caused by diet-induced obesity in female skeletal muscles with distinct fibre type compositions. Key points Feeding female Wistar rats a high-fat sucrose-enriched diet (HFS) led to diacylglycerol (DAG)-induced PKC activation and insulin resistance in oxidative and glycolytic skeletal muscles. HFS diet-induced toll-like receptor 4 (Tlr4) expression did not lead to increased ceramide content in female skeletal muscles. In highly glycolytic female muscles, elevated TAG content and markers of inflammation underlay HFS diet-induced insulin resistance. The HFS diet suppressed glucose oxidation and increased lactate production in oxidative and glycolytic female muscles. Increased Dgat2 mRNA expression likely diverted most of the intramyocellular acyl-CoAs toward TAG synthesis and prevented ceramide formation in skeletal muscles of HFS-fed female rats.

Single-pion production in electron-proton interactions

Abstract: This paper presents an extension of the MK single-pion production model [Kabirnezhad, Phys. Rev. D 97, 013002 (2018); Phys. Rev. D 102, 053009 (2020)] to high hadron invariant mass ($W$) and high momentum transfer (${Q}^{2}$) to conform to the predictions of perturbative QCD due to the quark-hadron duality evidence. New form factors for several resonances and nonresonant background in the electron-nucleon cross sections are determined taking into account the experimental data and improved evaluation techniques. Fits to electron-proton scattering data are used to constrain free parameters and to assign the related uncertainties of the model. The results from this work can be used to determine the vector current in the corresponding neutrino-nucleon cross sections, which is an important input for event generators in long-baseline neutrino-oscillation measurements.

``See You in Your Next Life'': Creativity, the Zhuangzi, and Grief

Abstract: Drawing from cross-cultural work on creativity undertaken within philosophical psychology, as well as contemporary commentaries on the philosophy of the Zhuangzi, this article motivates a conception of creativity that emphasizes spontaneity and adaptivity—rather than novelty or originality—engendered by embracing you 遊 (“wandering”). It argues that this approach to creativity can enable us to understand certain forms of religious experiences, especially those related to grief and bereavement, as creative in a sense that is compatible with both: i) views that emphasize the capacity of religious experiences to connect us with something supernatural, immaterial, or non-physical and, ii) views that emphasize the capacity of religious experiences to connect us with something natural, material, or physical. Additionally, it elaborates how these reflections might pave the way for further cross-cultural inquiries—empirical and otherwise—into the nature and value of religious experience

Gray Matter Volume as Evidence for Cognitive Reserve in Bilinguals With Mild Cognitive Impairment

Abstract: Compared with monolinguals, bilinguals have a later onset of mild cognitive impairment (MCI) and Alzheimer disease symptoms and greater neuropathology at similar cognitive and clinical levels. The present study follows a previous report showing the faster conversion from MCI to Alzheimer disease for bilingual patients than comparable monolinguals, as predicted by a cognitive reserve (CR).Identify whether the increased CR found for bilinguals in the previous study was accompanied by greater gray matter (GM) atrophy than was present for the monolinguals.A novel deep-learning technique based on convolutional neural networks was used to enhance clinical scans into 1 mm MPRAGEs and analyze the GM volume at the time of MCI diagnosis in the earlier study.Twenty-four bilingual and 24 monolingual patients were diagnosed with MCI at a hospital memory clinic.Bilingual patients had more GM loss than monolingual patients in areas related to language processing, attention, decision-making, motor function, and episodic memory retrieval. Bilingualism and age were the strongest predictors of atrophy after other variables such as immigration and education were included in a multivariate model.CR from bilingualism is evident in the initial stages of neurodegeneration after MCI has been diagnosed.

Caregiver and Child Distress as Predictors of Dyadic Physiological Attunement During Vaccination

Abstract: Objective: Previous research discerned three groups of caregiver-toddler dyads that differed in their physiological co-regulatory patterns, also known as physiological attunement, during routine vaccinations in the second year of life. One group of dyads (80% of sample) displayed an attuned regulatory pattern and two groups of dyads (20% of sample) showed maladaptive attunement patterns (i.e., a lack of attunement or misattunement). The objective of the current study was to examine how well pain-related distress of children and caregivers during vaccination predicted these patterns. Methods: Caregiver-toddler dyads (N = 189) were part of a longitudinal cohort observed at either 12-, 18-, or 24-month vaccination appointments. Caregiver self-report of worry was assessed before and after the needle and child behavioural pain-related distress was also measured during the vaccination appointment. Logistic regression was used to determine how well these variables predicted caregiver-child physiological attunement patterns, as indexed by high-frequency heart rate variability. Results: Higher behavioural pain-related distress at various timepoints after the needle were associated with membership in the dyad groups that showed misattunement or lack of attunement. Further, caregivers with higher pre-needle worry and lower post-needle worry had a greater likelihood of belonging to groups that showed a maladaptive attunement pattern. Discussion: Findings suggest that caregivers who experience distress associated with their toddlers’ vaccination experience more difficulty co-regulating with their child during vaccination, and these children are at risk of experiencing higher levels of pain-related distress. This research highlights the need to help caregivers support their children’s regulation during vaccination.

Legislation, Greek and Roman

Abstract: Legislation is distinct from other sources of law such as unwritten custom and judicial decisions by judges or juries. Legislation first appeared in the Greek and Roman world with the introduction of writing and was always associated with a legislative body or person(s) with delegated rule-making authority. Legislation is one part of a larger legal culture in the Greek and Roman world. How legislative rules were enacted, interpreted, applied, and amended was largely determined by specific social and political circumstances.

Memory impairment in the D2.<i>mdx</i> mouse model of Duchenne muscular dystrophy is prevented by the adiponectin receptor agonist ALY688

Abstract: What is the central question of this study? Can adiponectin receptor agonism improve recognition memory in a mouse model of Duchenne muscular dystrophy? What is the main finding and its importance? Short-term treatment with the new adiponectin receptor agonist ALY688 improves recognition memory in D2.mdx mice. This finding suggests that further investigation into adiponectin receptor agonism is warranted, given that there remains an unmet need for clinical approaches to treat this cognitive dysfunction in people with Duchenne muscular dystrophy.Memory impairments have been well documented in people with Duchenne muscular dystrophy (DMD). However, the underlying mechanisms are poorly understood, and there is an unmet need to develop new therapies to treat this condition. Using a novel object recognition test, we show that recognition memory impairments in D2.mdx mice are completely prevented by daily treatment with the new adiponectin receptor agonist ALY688 from day 7 to 28 of age. In comparison to age-matched wild-type mice, untreated D2.mdx mice demonstrated lower hippocampal mitochondrial respiration (carbohydrate substrate), greater serum interleukin-6 cytokine content and greater hippocampal total tau and Raptor protein contents. Each of these measures was partly or fully preserved after treatment with ALY688. Collectively, these results indicate that adiponectin receptor agonism improves recognition memory in young D2.mdx mice.

Mapping the impact of levee failure on flood risks: A Toronto case study

Abstract: Urban areas are frequently built along rivers and earthen levees are commonly used to protect areas from fluvial floods. Levees are designed to protect assets from flooding, however, they deteriorate over time. Maintenance checks are required to maintain their efficacy but even in good condition, a levee structure may fail during a flood, hence flood risk assessments in fluvial areas require an investigation of levee failures, e.g. by overtopping, erosion, or sliding. In this research, we investigate the failure probability due to backward erosion of an adapted levee in the Etobicoke Creek watershed, in Toronto, Canada. The study proposes an adapted levee as the residential area is often flooded. Backward erosion is the most probable and challenging failure mechanism for our case study based on the levee shape and soil type. For this probabilistic study, the levee was modelled using GeoStudio, which produces seepage analysis from geotechnical and hydrological parameters. The seepage analysis provides hydraulic gradients from which we determine the failure probability of backward erosion based on a critical hydraulic gradient value. To obtain the flood hazard, we use a steady flow hydraulic model (HEC-RAS) to simulate the 350-years return period flow through the River. We compare two backward failure scenarios: one with a levee breach and one without, to better understand how failure of the levee will impact flood risks, and therefore, highlighting the importance of on-going levee maintenance. To obtain flood risk maps, the flood hazard (i.e., flood extent) is combined with flood exposure. The flood exposure includes land-use type (residential, commercial, etc.) and demographic information. Flood hazard and exposure data are combined using ArcGIS. The flood hazard and exposure rasters are reclassified in a new scale to determine flood risk. We then overlay the rasters to determine the spatial distribution of flood risk for both scenarios. We compare the resulting flood risk maps and calculate the change in flood risks for the area protected by the levee. Accounting for potential failure of infrastructure in flood risk mapping results in more accurate risk estimations. We also demonstrate the positive impact of the levee.

Equity &amp; Excellence are Mutually Conducive; A response to Ms. Wente, Globe &amp; Mail June 10th

Abstract: <p>[p.1]: "Dear Ms Wente</p> <p>I read with interest your opinion piece in the June 10th issue of the G & M. The piece was, I assume, intentionally provocative. I am compelled to respond because yours is a voice of privilege, on a national platform. You suggest that academia operates within a system that is fair and equal but surely you know that, like the rest of society, this is a falsehood. But the most privileged are the last to see inequities because they have benefited the most."</p>

Uncertainty Modelling

Abstract: Organizations attempt to create value for their customers while managing different uncertainties. Uncertainties in supply chains offer both opportunities and challenges to decision-makers. We start this chapter by reviewing three uncertainty types (i.e. truth, epistemological and ontological uncertainty) and discuss why the ontological uncertainty deserves special attention. We study the uncertainty modelling approach along two dimensions to address the challenges of managing the ontological uncertainty. First, we introduce the additive and multiplicative demand models to capture the evolutionary dynamics of uncertainty. Second, we focus on advanced methods, such as the fast Fourier transformation (FFT) and demand regularization, to model complex demand dynamics when demand is formed as combination of different uncertain elements.

Cover Feature: Cost‐Effective Vat Orange 3‐Derived Organic Cathodes for Electrochemical Energy Storage (Batteries &amp; Supercaps 2/2023)

Abstract: The Cover Feature illustrates the Vat Orange 3 based energy storage devices. The Monkey King, one of Chinese classic cartoon characters, stepping on the “vat orange 3” cloud, is starting his battle journey. More information can be found in the Research Article by T. Baumgartner, X. He and co-workers.

On-orbit Calibration of GRACE and GRACE-FO accelerometers

Abstract: The onboard GRACE and GRACE-FO accelerometers measure the non-gravitational accelerations of the spacecraft that are indispensable for the modelling of the Earth&#8217;s gravity field since they are subtracted from the GPS POD total accelerations to isolate the pure gravitational accelerations. The accelerometers, like any other instrument, must be calibrated very accurately to serve their purpose but the calibration cannot be done as per standard metrological methods, in a laboratory environment due to the influence of the gravitational signal which is almost 10 orders of magnitude larger. Many researchers have proposed different approaches for the estimation of the bias and the scale factor of the accelerometers, most of which are based on the physical models of the non-gravitational accelerations The drawback of these methods is the dependency of the calibration on the theoretical models and specifically on the drag models that exhibit the highest uncertainty due to the complexity of the upper atmosphere. An alternative, on-orbit calibration of the accelerometers is proposed that is commensurate with standard metrological methods and thus it is based only on the satellite measurements. The idea behind this method lies in a time-reversal method widely used in radar applications for the detection and measurement of known but distorted pulses hidden in the scattered signal from the reflectors. By analogy to radar applications, the total accelerations estimated from GPS through numerical double POD differentiation, correspond to the &#8216;transmitted signal&#8217; (calibrated) and the accelerometer measurements (uncalibrated) comprise the &#8216;return signal&#8217; (scattered signal). &#160;The key to this method is that the penumbra transitions are present in both signals and play the role of the known calibration pulse. Examples of 30 daily scale factors are calculated for different operational periods during lower and higher solar activity of GRACE and GRACE-FO and the accelerometer bias is computed by a daily polynomial fit. The results show a robust estimation of the scale factor and bias of the accelerometers. The thermal sensitivity of the accelerometer and its correlation with the &#946;&#8217; angle is investigated.&#160;

Reply on RC1

Abstract: Abstract. Because of their computational expense, models with comprehensive tropospheric chemistry have typically been run with prescribed sea surface temperatures (SSTs), which greatly limits the model's ability to generate climate responses to atmospheric forcings. In the past few years, however, several fully-coupled models with comprehensive tropospheric chemistry have been developed. For example, the Community Earth System Model version 2 with the Whole Atmosphere Community Climate Model version 6 as its atmospheric component (CESM2-WACCM6) has implemented fully interactive tropospheric chemistry with 231 chemical species as well as a fully coupled ocean. Earlier versions of this model used a "SOAG scheme" that prescribes bulk emission of a single gas-phase precursor to secondary organic aerosols (SOAs). The additional chemistry in CESM2-WACCM6 simulates the chemistry of a comprehensive range of volatile organic compounds (VOCs) responsible for tropospheric aerosol formation. Such a model offers an opportunity to examine the full climate effects of comprehensive tropospheric chemistry. To examine these effects, 141-year preindustrial control simulations were performed using the following two configurations: 1) the standard CESM2-WACCM6 configuration with interactive chemistry over the whole atmosphere (WACtl), and 2) a simplified CESM2-WACCM6 configuration using a SOAG scheme in the troposphere and interactive chemistry in the middle atmosphere (MACtl). The middle atmospheric chemistry is the same in both configurations, and only the tropospheric chemistry differs. Differences between WACtl and MACtl were analyzed for various fields. Regional differences in annual mean surface temperature range between -4 K and 4 K. These surface temperature changes are comparable to those produced over a century in future climate change scenarios, which motivates future research to investigate possible influences of VOC chemistry on anthropogenic climate change. In the zonal average, there is widespread tropospheric cooling in the extratropics. Longwave forcers are shown to be unlikely drivers of this cooling, and possible shortwave forcers are explored. Evidence is presented that the climate response is primarily due to increased organic nitrates in the troposphere, increased sulfate aerosols in the stratosphere and cloud feedbacks. The possible chemical mechanisms responsible for these changes are discussed. As found in earlier studies, enhanced internal mixing with SOAs in WACtl causes reduced black carbon (BC) and reduced primary organic matter (POM), which are not directly influenced by VOC chemistry. These BC and POM reductions might also contribute to cooling in the Northern Hemisphere. The extratropical tropospheric cooling results in dynamical changes, such as equatorward shifts of the midlatitude jets, which in turn drive extratropical changes in clouds and precipitation. In the tropical upper troposphere, cloud-driven increases in shortwave heating appear to weaken and expand the Hadley circulation, which in turn drives changes in tropical and subtropical precipitation.

Psychology, Law, Ethics, Telehealth, and the Global Pandemic

Abstract: The chapter reviews ethical issues pertinent to tele-assessmentAssessment, tele- in psychological injuryInjury, psychological and discusses the constraints and limitations involved. It follows an overview of divergent recommendations on the feasibility of conducting such assessmentsAssessment remotely. Psychological injuryInjury, psychological evaluations are conducted in cases of negligent injuryInjury leading to tort lawsuits, worker compensation cases, disability determinations, military veterans’ examinations, malpractice lawsuits, harassment and discrimination cases, sexual assaults, and so on, making them high stakes, forensic, and scrupulously examined in court and related venues. Remote testing in these assessmentsAssessment is fraught with challenges related to conducting quality synchronous, live interviews and supervising online testing by respondents using test company platforms. The challenges in conducting these assessments are reviewed, from the most basic, such as using secure platforms, to the most complex, such as the ethical and legal context for telehealthTelehealth assessments of this type. The latter include obtaining fully-informed, voluntary consentConsent to participation in the assessmentAssessment remotely, despite the increased limitations and risksRisk inherent in the remote modality. The chapter makes recommendations on how to proceed when the assessments are mandated or otherwise in the case’s best interests and offers a sample telepsychologyTelepsychology informed consentConsent, informed form discussed in detail. The threat to the reliability, validity, and probative value of these assessmentsAssessment for court purposes calls for a cautious attitude in the assessments. The chapter reviews the American Psychological Association EthicsEthics Code ( https://www.apa.org/ethics/code/#:%7E:text=Copyright%20%C2%A9%202,017%20American%20Psychological%20Association.%20All%20rights,five%20General%20Principles%20%28A-E%29%20and%20specific%20Ethical%20Standards ) concerning these assessmentsAssessment and considers the legal ramifications. Conclusions relate to admissibilityAdmissibility to the court of psychological tele-assessmentsAssessment, tele-.

Collaborative Learning in the Online Environment

Abstract: The chapter is based on the qualitative research conducted in a Canadian post-secondary institution. The researcher applied an exploratory case study methodology and a semi-structured interview approach. The participants were students who studied in fully online classes, instructors who delivered online courses, and instructional designers of the online courses. They answered sets of questions about the relevance of interpersonal relationships among online classmates to learning. The respondents also discussed how those relationships could be initiated, developed, and cultivated in an online course by means of instructional design and the implementation of facilitation strategies and techniques. This chapter examines how instructional designers and instructors can design and foster a collaborative learning environment. The research topic is beneficial to adult education instructors, instructional designers, faculty, higher education administrators, educational technologists, students, and scholars who are interested in researching course design for collaborative online learning.