Fast, Sample-Efficient, Affine-Invariant Private Mean and Covariance Estimation for Subgaussian Distributions

We present a fast, differentially private algorithm for high-dimensional covariance-aware mean estimation with nearly optimal sample complexity. Only exponential-time estimators were previously known to achieve this guarantee. Given $n$ samples from a (sub-)Gaussian distribution with unknown mean $\mu$ and covariance $\Sigma$, our $(\varepsilon,\delta)$-differentially private estimator produces $\tilde{\mu}$ such that $\|\mu - \tilde{\mu}\|_{\Sigma} \leq \alpha$ as long as $n \gtrsim \tfrac d {\alpha^2} + \tfrac{d \sqrt{\log 1/\delta}}{\alpha \varepsilon}+\frac{d\log 1/\delta}{\varepsilon}$. The Mahalanobis error metric $\|\mu - \hat{\mu}\|_{\Sigma}$ measures the distance between $\hat \mu$ and $\mu$ relative to $\Sigma$; it characterizes the error of the sample mean. Our algorithm runs in time $\tilde{O}(nd^{\omega - 1} + nd/\varepsilon)$, where $\omega < 2.38$ is the matrix multiplication exponent. We adapt an exponential-time approach of Brown, Gaboardi, Smith, Ullman, and Zakynthinou (2021), giving efficient variants of stable mean and covariance estimation subroutines that also improve the sample complexity to the nearly optimal bound above. Our stable covariance estimator can be turned to private covariance estimation for unrestricted subgaussian distributions. With $n\gtrsim d^{3/2}$ samples, our estimate is accurate in spectral norm. This is the first such algorithm using $n= o(d^2)$ samples, answering an open question posed by Alabi et al. (2022). With $n\gtrsim d^2$ samples, our estimate is accurate in Frobenius norm. This leads to a fast, nearly optimal algorithm for private learning of unrestricted Gaussian distributions in TV distance. Duchi, Haque, and Kuditipudi (2023) obtained similar results independently and concurrently.Comment: 44 pages. New version fixes typos and includes additional exposition and discussion of related wor

Comparison Between Single and Combined Clinical Postural Stability Tests in Individuals With and Without Chronic Ankle Instability

Objective: To determine if a single or/and combined clinical tests match group membership based on self-reported ankle function. Design: Cross-sectional. Setting: Biomechanics Laboratory. Participants: From participants, 58 meeting inclusion/exclusion criteria were divided into a chronic ankle instability (CAI) group (n = 25) who reported ≤25 on the Cumberland Ankle Instability Tool (CAIT) and a history of moderate–severe ankle sprain(s) and a control group (n = 33) who reported ≥29 on the CAIT and no history of ankle sprain(s). Interventions: Participants completed the following clinical tests: Foot Lift Test (FLT), the Star Excursion Balance Test (SEBT), the Single-Leg Hop Test (SLHT), and the Time in Balance Test (TIB) in a randomized order. A linear regression model was applied to determine measures that matched ankle group membership. Main Outcome Measures: The mean of SEBT reach distance was normalized to percentage leg length. The mean of number of errors in the FLT was recorded. The SLHT and TIB were reported as time in seconds, and the means were calculated. Results: The most parsimonious combination of tests (SLHT and SEBT) resulted in correctly matching 70.69% (41/58) of participants into groups, which was significantly better than chance. The multiple correlation coefficients (R value) for combining the SLHT and SEBT was 0.39. Conclusions: Using SLHT and SEBT resulted in improved recognition of participants designated into the CAI or control groups. Self-report perception of ankle function provides limited information for clinicians and researchers. Using multiple clinical function tests may be more helpful in determining deficits and intervention effectiveness

The relationship between acute pain and dynamic postural stability indices in individuals with patellar tendinopathy

Background Patellar tendinopathy is a common condition resulting in persistent pain, frequently reported during physical activity. The relationship between dynamic postural stability and pain in these individuals is unclear and how it may affect postural stability. Research Question Is there a relationship between acute pain and dynamic postural stability indices in individuals with patellar tendinopathy? Methods Twenty-two recreationally active individuals with patellar tendinopathy participated. Participants performed a two-legged jump and landed on a single test-limb on a force platform. They completed 100 mm visual analogue scales (VAS) before and after landing trials. Anterior-posterior (APSI), medial-lateral (MLSI), vertical (VSI), and composite (DPSI) stability indices were calculated from ground reaction force data. The relationship between stability indices and VAS for pain as well as pain change scores were assessed via non-parametric Spearman’s rho (ρ) rank correlations (p≤.05). Results Baseline pain was not significantly correlated with any stability indices. Post-landing pain was significantly correlated with MLSI (ρ = 0.540, p = 0.004) while, VSI (ρ = 0.353, p = 0.053) and DPSI (ρ = 0.347, p = 0.057) had moderate, yet insignificant correlations. Pain change scores demonstrated a large correlation with MLSI (ρ = 0.598, p = 0.002). Significance As pain increased in individuals with patellar tendinopathy, dynamic postural stability indices values increased, indicating more difficulty transitioning from a dynamic to static state. Although balance deficits are not typically associated with patellar tendinopathy, it appears pain and dynamic postural stability may be related in these individuals

Non-disabled secondary school children’s lived experiences of a wheelchair basketball programme delivered in the East of England

Frequently an unquestioned belief is held in UK schools in the value of ‘normalised’ ability in physical education. Consequently inclusion of disabled students can be problematical. Negative perceptions of disability are rarely challenged. This study investigated the embodied experiences of 50 non-disabled secondary school pupils during a programme designed to introduce disability sport to non-disabled schoolchildren entitled ‘The Wheelchair Sports Project.’ Wheelchair Basketball sessions were delivered by coaches during physical education for a 12 week period. 50 pupils aged between 10 and 12 years took part. Non-participant observations were completed during the intervention and guided group interviews were completed with 40 participants pre and post project. Bourdieu’s theoretical framework was utilized during data analysis. The impact of the project on pupils’ perceptions of physical disability was investigated. Prior to the project, pupils emphasized the ‘otherness’ of disabled bodies and described disability sport as inferior and not ‘real.’ Observations highlighted how pupils’ experienced physical challenges adapting to wheelchair basketball. Pupils struggled to control wheelchairs and frequently diverged from acceptable behaviour by using their lower limbs to ‘cheat.’ Post-programme interviews demonstrated pupils’ perceptions of physical disability altered due to their embodied experiences. Pupils described high physical demands of wheelchair basketball and began to focus upon similarities between themselves and physically disabled individuals. However, no reference was made to mental or psychological disability, emphasizing the specificity of the effects of pupils’ embodied experiences on their habitus’

Single-limb landing biomechanics are altered and patellar tendinopathy related pain is reduced with acute infrapatellar strap application

Background Patellar tendinopathy, a common condition of the knee, is often treated with patellar tendon straps to control pain during dynamic activity. Little is known regarding their effect on pain, landing kinematics and kinetics with their application. The purpose of this study was to determine if patellar tendon straps influenced pain, kinematics at landing and ground reaction forces in individuals with patellar tendinopathy versus healthy controls. Methods Thirty participants with patellar tendinopathy and 30 controls participated. They completed single-limb landings with and without patellar tendon straps while pain, three-dimensional kinematics and vertical ground reaction forces were measured. A multivariate analysis of variance was completed to determine the differences in strapping condition and group for the dependent variables. Results Individuals with patellar tendinopathy demonstrated a significant decrease in pain (no strap = 37.1 ± 22.1 mm (mean ± SD), strap = 28.0 ± 18.5 mm (mean ± SD)). With the strap at landing all participants displayed less hip rotation (F = 7.16, p = .01), knee adduction (F = 10.20, p = .002), ankle inversion (F = 4.60, p = .04), and peak vertical ground reaction force (F = 7.30, p = .009). Conclusions Patellar tendon straps reduced pain in those with patellar tendinopathy. Additionally, with the strap, individuals landed in a more neutral alignment and decreased landing forces which could provide a benefit to those with patellar tendinopathy

Functional performance deficits in adolescent athletes with a history of lateral ankle sprain(s)

Objective To determine if adolescent athletes with a history of lateral ankle sprain(s) (LAS) displayed deficits on functional performance tests (FPTs) and if deficits on FPT were related to the number of previous LAS. Design Cross-sectional study. Setting Biomechanics Laboratory. Participants The injured group (n = 24) had a history of ≥1 moderate-severe LAS. The uninjured group (n = 34) had no history of LAS. Main outcome measure(s) The average reach distance of three trials in each direction of the star excursion balance test (SEBT) was normalized to leg length (%). The average of two trials of single-leg-hop test (SLHT) was calculated in seconds. Results The injured group performed significantly worse in 3 directions of SEBT than the uninjured group (P \u3c 0.05). SLHT was significantly slower in the injured group compared to the uninjured group (P \u3c 0.05). Statistically significant, strong to moderate inverse relationships were found between the numbers of LAS and each of the three directions of the SEBT (P ≤ 0.01). No relationship was revealed between the number of LAS and the SLHT (P \u3e 0.05). Conclusion(s) Adolescent athletes with a history of LAS exhibit functional performance deficits on the SEBT and SLHT. Therefore, the SEBT and SLHT may provide clinicians cost- and time-effective objective tools

Cross-cultural adaptation, reliability, and validation of the Korean version of the identification functional ankle instability (IdFAI)

Purpose: To cross-culturally adapt the Identification Functional Ankle Instability for use with Korean-speaking participants. Methods: The English version of the IdFAI was cross-culturally adapted into Korean based on the guidelines. The psychometric properties in the Korean version of the IdFAI were measured for test-retest reliability, internal consistency, criterion-related validity, discriminative validity, and measurement error 181 native Korean-speakers. Results: Intra-class correlation coefficients (ICC2,1) between the English and Korean versions of the IdFAI for test–retest reliability was 0.98 (standard error of measurement = 1.41). The Cronbach’s alpha coefficient was 0.89 for the Korean versions of IdFAI. The Korean versions of the IdFAI had a strong correlation with the SF-36 (rs = −0.69, p \u3c .001) and the Korean version of the Cumberland Ankle Instability Tool (rs = −0.65, p \u3c .001). The cutoff score of \u3e10 was the optimal cutoff score to distinguish between the group memberships. The minimally detectable change of the Korean versions of the IdFAI score was 3.91. Conclusion: The Korean versions of the IdFAI have shown to be an excellent, reliable, and valid instrument. The Korean versions of the IdFAI can be utilized to assess the presence of Chronic Ankle Instability by researchers and clinicians working among Korean-speaking populations. Implications for rehabilitation The high recurrence rate of sprains may result into Chronic Ankle Instability (CAI). The Identification of Functional Ankle Instability Tool (IdFAI) has been validated and recommended to identify patients with Chronic Ankle Instability (CAI). The Korean version of the Identification of Functional Ankle Instability Tool (IdFAI) may be also recommend to researchers and clinicians for assessing the presence of Chronic Ankle Instability (CAI) in Korean-speaking population

Complete Genome Sequence of Pelosinus fermentans JBW45, a Member of a Remarkably Competitive Group of Negativicutes in the Firmicutes Phylum.

The genome of Pelosinus fermentans JBW45, isolated from a chromium-contaminated site in Hanford, Washington, USA, has been completed with PacBio sequencing. Nine copies of the rRNA gene operon and multiple transposase genes with identical sequences resulted in breaks in the original draft genome and may suggest genomic instability of JBW45

Mouse WRN Helicase Domain Is Not Required for Spontaneous Homologous Recombination-Mediated DNA Deletion

Werner syndrome is a rare disorder that manifests as premature aging and age-related diseases. WRN is the gene mutated in WS, and is one of five human RecQ helicase family members. WS cells exhibit genomic instability and altered proliferation, and in vitro studies suggest that WRN has a role in suppressing homologous recombination. However, more recent studies propose that other RecQ helicases (including WRN) promote early events of homologous recombination. To study the role of WRN helicase on spontaneous homologous recombination, we obtained a mouse with a deleted WRN helicase domain and combined it with the in vivo pink-eyed unstable homologous recombination system. In this paper, we demonstrate that WRN helicase is not necessary for suppressing homologous recombination in vivo contrary to previous reports using a similar mouse model