Growth and splitting of neural sequences in songbird vocal development

Neural sequences are a fundamental feature of brain dynamics underlying diverse behaviours, but the mechanisms by which they develop during learning remain unknown. Songbirds learn vocalizations composed of syllables; in adult birds, each syllable is produced by a different sequence of action potential bursts in the premotor cortical area HVC. Here we carried out recordings of large populations of HVC neurons in singing juvenile birds throughout learning to examine the emergence of neural sequences. Early in vocal development, HVC neurons begin producing rhythmic bursts, temporally locked to a prototype syllable. Different neurons are active at different latencies relative to syllable onset to form a continuous sequence. Through development, as new syllables emerge from the prototype syllable, initially highly overlapping burst sequences become increasingly distinct. We propose a mechanistic model in which multiple neural sequences can emerge from the growth and splitting of a commo n precursor sequence.National Institutes of Health (U.S.) (Grant R01DC009183)National Science Foundation (U.S.) (Grant DGE-114747

Accuracy of wearable physical activity trackers in people with Parkinson's disease

Introduction: The purpose of this study was to determine the accuracy of the Fitbit Charge HR (TM) and Garmin vivosmart (R) HR in measuring steps and reflecting intensity of activity in people with Parkinson's disease (PD).Methods: Thirty-three people with mild-moderate PD performed six, two-minute indoor walks at their self-selected walking pace, and at target cadences of 60, 80, 100, 120 and 140 beats/min. A 500 m outdoor walk with terrain challenges was also performed. Step count was recorded by the two wrist-worn activity trackers (Fitbit Charge HR (TM) and Garmin vivosmart (R) HR) and compared to an accelerometer (ActivPAL3 (TM)). Intensity was recorded by a portable breath-by-breath gas analyser (VO2), heart rate and Borg scale.Results: Both commercial activity trackers had low error ( 0.68; p = 80steps/min. The Fitbit had higher error was less consistent for all target cadences >= 80steps/min. Cadence measured by the Fitbit and Garmin weakly reflected increases in heart rate (ICCs 0.27-0.28; p 0.05).Conclusion: The Garmin device was more accurate at reflecting step count across a broader range of walking cadences than the Fitbit, but neither strongly reflected intensity of activity. While not intended to replace research grade devices, these wrist-worn devices may be a clinically useful adjunct to exercise therapy to increase physical activity in people with PD

The Role of Carbonate Factories and Sea Water Chemistry on Basin-Wide Ramp to High-Relief Carbonate Platform Evolution: Triassic, Nanpanjiang Basin, South China

The end-Permian extinction and its aftermath altered carbonate factories globally for millions of years, but its impact on platform geometries remains poorly understood. Here, the evolution in architecture and composition of two exceptionally exposed platforms in the Nanpanjiang Basin are constrained and compared with geochemical proxies to evaluate controls on platform geometries. Geochemical proxies indicate elevated siliciclastic and nutrient fluxes in the basal Triassic, at the Induan—Olenekian boundary and in the uppermost Olenekian. Cerium/Ce* shifts from high Ce/Ce* values and a lack of Ce anomaly indicating anoxia during the Lower Triassic to a negative Ce anomaly indicating oxygenation in the latest Olenekian and Anisian. Uranium and Mo depletion represents widespread anoxia in the world\u27s oceans in the Early Triassic with progressive oxygenation in the Anisian. Carbonate factories shifted from skeletal in the Late Permian to abiotic and microbial in the Early Triassic before returning to skeletal systems in the Middle Triassic, Anisian coincident with declining anoxia. Margin facies shifted to oolitic grainstone in the Early Triassic with development of giant ooids and extensive marine cements. Anisian margins, in contrast, are boundstone with a diverse skeletal component. The shift in platform architecture from ramp to steep, high-relief, flat-topped profiles is decoupled from carbonate compositions having occurred in the Olenekian prior to the onset of basin oxygenation and biotic stabilisation of the margins. A basin-wide synchronous shift from ramp to high-relief platforms points to a combination of high subsidence rate and basin starvation coupled with high rates of abiotic and microbial carbonate accumulation and marine cement stabilisation of oolitic margins as the primary causes for margin up-building. High sea water carbonate saturation resulting from a lack of skeletal sinks for precipitation, and basin anoxia promoting an expanded depth of carbonate supersaturation, probably contributed to marine cement stabilisation of margins that stimulated the shift from ramp to high-relief platform architecture

Evidence for hierarchical black hole mergers in the second LIGO--Virgo gravitational-wave catalog

We study the population properties of merging binary black holes in the second LIGO--Virgo Gravitational-Wave Transient Catalog assuming they were all formed dynamically in gravitationally bound clusters. Using a phenomenological population model, we infer the mass and spin distribution of first-generation black holes, while self-consistently accounting for hierarchical mergers. Considering a range of cluster masses, we see compelling evidence for hierarchical mergers in clusters with escape velocities $\gtrsim 100~\mathrm{km\,s^{-1}}$. For our most probable cluster mass, we find that the catalog contains at least one second-generation merger with $99\%$ credibility. We find that the hierarchical model is preferred over an alternative model with no hierarchical mergers (Bayes factor $\mathcal{B} > 1400$) and that GW190521 is favored to contain two second-generation black holes with odds $\mathcal{O}>700$, and GW190519, GW190602, GW190620, and GW190706 are mixed-generation binaries with $\mathcal{O} > 10$. However, our results depend strongly on the cluster escape velocity, with more modest evidence for hierarchical mergers when the escape velocity is $\lesssim 100~\mathrm{km\,s^{-1}}$. Assuming that all binary black holes are formed dynamically in globular clusters with escape velocities on the order of tens of $\mathrm{km\,s^{-1}}$, GW190519 and GW190521 are favored to include a second-generation black hole with odds $\mathcal{O}>1$. In this case, we find that $99\%$ of black holes from the inferred total population have masses that are less than $49\,M_{\odot}$, and that this constraint is robust to our choice of prior on the maximum black hole mass.Comment: 15 pages, 11 figures, 1 appendi

Identifying inequitable healthcare in older people: systematic review of current research practice

$\textbf{Background:}$ There is growing consensus on the importance of identifying age-related inequities in the receipt of public health and healthcare interventions, but concerns regarding conceptual and methodological rigour in this area of research. Establishing age inequity in receipt requires evidence of a difference that is not an artefact of poor measurement of need or receipt; is not warranted on the grounds of patient preference or clinical safety; and is judged to be unfair. $\textbf{Method:}$ A systematic, thematic literature review was undertaken with the objective of characterising recent research approaches. Studies were eligible if the population was in a country within the Organisation for Economic Co-operation and Development and analyses included an explicit focus on age-related patterns of healthcare receipt including those 60 years or older. A structured extraction template was applied. Extracted material was synthesised in thematic memos. A set of categorical codes were then defined and applied to produce summary counts across key dimensions. This process was iterative to allow reconciliation of discrepancies and ensure reliability. $\textbf{Results:}$ Forty nine studies met the eligibility criteria. A wide variety of concepts, terms and methodologies were used across these studies. Thirty five studies employed multivariable techniques to produce adjusted receipt-need ratios, though few clearly articulated their rationale, indicating the need for great conceptual clarity. Eighteen studies made reference to patient preference as a relevant consideration, but just one incorporated any kind of adjustment for this factor. Twenty five studies discussed effectiveness among older adults, with fourteen raising the possibility of differential effectiveness, and one differential cost-effectiveness, by age. Just three studies made explicit reference to the ethical nature of healthcare resource allocation by age. While many authors presented suitably cautious conclusions, some appeared to over-stretch their findings concluding that observed differences were ‘inequitable’. Limitations include possible biases in the retrieved material due to inconsistent database indexing and a focus on OECD country populations and studies with English titles. $\textbf{Conclusions:}$ Caution is needed among clinicians and other evidence-users in accepting claims of healthcare ‘ageism’ in some published papers. Principles for improved research practice are proposed.This research was funded by the National Institute for Health Research’s School for Public Health Research

Mentoring Impact on Leader Efficacy Development: A Field Experiment

While practitioners and scholars tout the importance of mentorship in leader development, few studies have empirically determined whether mentoring actually positively impacts a leader’s development, and if so, in what ways. In a longitudinal field experiment, we examined how a targeted mentorship program that unfolded over 6 months enhanced the development of protégés’ leader efficacy and performance. Results showed that the targeted mentorship intervention increased protégés’ level of leader efficacy more than a comparison intervention that was based on a more eclectic leadership education program delivered in a group setting. Leader efficacy then predicted rated leader performance. Both protégés’ preferences for feedback and trust in the mentor served as important moderators in contributing to the development of leader efficacy. Findings from this longitudinal field experiment could be used by educational institutions and other organizations to enhance their mentorship programs in content, focus, and evaluation of impact

Igbo-English intrasentential codeswitching and the Matrix Language Frame model

This paper uses data from Igbo-English intrasentential codeswitching involving mixed nominal expressions to test the Matrix Language Frame (MLF) model. The MLF model is one of the most highly influential frameworks used in the study of grammatical aspects of codeswitching. Three principles associated with it, the Matrix Language Principle, the Asymmetry Principle and the Uniform Structure Principle, were tested on data collected from informal conversations by educated adult Igbo-English bilinguals resident in Port Harcourt. The results of the analyses suggest general support for the three principles and for identifying Igbo-English as a “classic” case of codeswitching

Diversity in African languages: Selected papers from the 46th Annual Conference on African Linguistics

Diversity in African Languages contains a selection of revised papers from the 46th Annual Conference on African Linguistics, held at the University of Oregon. Most chapters focus on single languages, addressing diverse aspects of their phonology, morphology, semantics, syntax, information structure, or historical development. These chapters represent nine different genera: Mande, Gur, Kwa, Edoid, Bantu, Nilotic, Gumuzic, Cushitic, and Omotic. Other chapters investigate a mix of languages and families, moving from typological issues to sociolinguistic and inter-ethnic factors that affect language and accent switching. Some chapters are primarily descriptive, while others push forward the theoretical understanding of tone, semantic problems, discourse related structures, and other linguistic systems. The papers on Bantu languages reflect something of the internal richness and continued fascination of the family for linguists, as well as maturation of research on the family. The distribution of other papers highlights the need for intensified research into all the language families of Africa, including basic documentation, in order to comprehend linguistic diversities and convergences across the continent. In this regard, the chapter on Daats’íin (Gumuzic) stands out as the first-ever published article on this hitherto unknown and endangered language found in the Ethiopian-Sudanese border lands

Diversity in African languages: Selected papers from the 46th Annual Conference on African Linguistics

Diversity in African Languages contains a selection of revised papers from the 46th Annual Conference on African Linguistics, held at the University of Oregon. Most chapters focus on single languages, addressing diverse aspects of their phonology, morphology, semantics, syntax, information structure, or historical development. These chapters represent nine different genera: Mande, Gur, Kwa, Edoid, Bantu, Nilotic, Gumuzic, Cushitic, and Omotic. Other chapters investigate a mix of languages and families, moving from typological issues to sociolinguistic and inter-ethnic factors that affect language and accent switching. Some chapters are primarily descriptive, while others push forward the theoretical understanding of tone, semantic problems, discourse related structures, and other linguistic systems. The papers on Bantu languages reflect something of the internal richness and continued fascination of the family for linguists, as well as maturation of research on the family. The distribution of other papers highlights the need for intensified research into all the language families of Africa, including basic documentation, in order to comprehend linguistic diversities and convergences across the continent. In this regard, the chapter on Daats’íin (Gumuzic) stands out as the first-ever published article on this hitherto unknown and endangered language found in the Ethiopian-Sudanese border lands