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We consider fully three-dimensional time-dependent outflow from a source into a surrounding fluid of different density. The source is distributed over a sphere of finite radius. The nonlinear problem is formulated using a spectral approach in which two streamfunctions and the density are represented as a Fourier-type series with time-dependent coefficients that must be calculated. Linearized theories are also discussed and an approximate stability condition for early stages in the outflow is derived. Nonlinear solutions are presented and different outflow shapes adopted by the fluid interface are investigated.
Long-duration gamma-ray burst (GRB) afterglow observations offer cutting-edge opportunities to characterise the star formation history of the Universe back to the epoch of reionisation, and to measure the chemical composition of interstellar and intergalactic gas through absorption spectroscopy. The main barrier to progress is the low efficiency in rapidly and confidently identifying which bursts are high redshift (
$z > 5$
) candidates before they fade, as this requires low-latency follow-up observations at near-infrared wavelengths (or longer) to determine a reliable photometric redshift estimate. Since no current or planned gamma-ray observatories carry near-infrared telescopes on-board, complementary facilities are needed. So far this task has been performed by instruments on the ground, but sky visibility and weather constraints limit the number of GRB targets that can be observed and the speed at which follow-up is possible. In this work we develop a Monte Carlo simulation framework to investigate an alternative approach based on the use of a rapid-response near-infrared nano-satellite, capable of simultaneous imaging in four bands from
m (a mission concept called SkyHopper). Using as reference a sample of 88 afterglows observed with the GROND instrument on the MPG/ESO telescope, we find that such a nano-satellite is capable of detecting in the H-band (1.6
$72.5\% \pm 3.1\%$
of GRBs concurrently observable with the Swift satellite via its UVOT instrument (and
$44.1\% \pm 12.3\%$
of high redshift (
) GRBs) within 60 min of the GRB prompt emission. This corresponds to detecting
GRB afterglows per year, of which 1–3 have
$z > 5$
. These rates represent a substantial contribution to the field of high-z GRB science, as only 23
$z > 5$
GRBs have been collectively discovered by the entire astronomical community over the last
yr. Future discoveries are critically needed to take advantage of next generation follow-up spectroscopic facilities such as 30m-class ground telescopes and the James Webb Space Telescope. Furthermore, a systematic space-based follow-up of afterglows in the near-infrared will offer new insight on the population of dusty (‘dark’) GRBs which are primarily found at cosmic noon (
). Additionally, we find that launching a mini-constellation of 3 near-infrared nano-satellites would increase the detection fraction of afterglows to
and substantially reduce the latency in the photometric redshift determination.
Marie Roué, Centre National de la Recherche Scientifique (CNRS), Paris,Douglas Nakashima, United Nations Educational, Scientific and Cultural Organization (UNESCO), France,Igor Krupnik, Smithsonian Institution, Washington DC
Assessing potential drivers of and linkages between sea ice retreat or thinning across Arctic Russia and maintenance of the ancient and unique social-ecological systems of the Indigenous reindeer-herding Nenets is a pressing task. Sea ice loss is accelerating in the Barents and Kara Seas in the northwestern region of Arctic Russia. Warming summer air temperatures in recent decades have been linked to more frequent and sustained summer high-pressure systems over West Siberia but not to sea ice retreat. At the same time, autumn/winter rain-on-snow events across the region have become more frequent and intense. Two major rain-on-snow events during November 2006 and 2013 led to massive winter reindeer mortality episodes on Yamal Peninsula, where tundra nomadism remains a vitally important livelihood activity for the indigenous Nenets.
Here we review evidence for autumn atmospheric warming and precipitation increases over Arctic coastal lands in proximity to Barents and Kara sea ice loss. Realizing mutual coexistence of tundra nomadism within the Arctic’s largest natural gas complex under a warming climate will require ready access to and careful interpretation of real-time meteorological and sea-ice data and modelling, as well as meaningful consultation with local communities.
Anhedonia is a core symptom of depression that predicts worse treatment outcomes. Dysfunction in neural reward circuits is thought to contribute to anhedonia. However, whether laboratory-based assessments of anhedonia and reward-related neural function translate to adolescents' subjective affective experiences in real-world contexts remains unclear.
We recruited a sample of adolescents (n = 82; ages 12–18; mean = 15.83) who varied in anhedonia and measured the relationships among clinician-rated and self-reported anhedonia, behaviorally assessed reward learning ability, neural response to monetary reward and loss (as assessed with functional magnetic resonance imaging), and repeated ecological momentary assessment (EMA) of positive affect (PA) and negative affect (NA) in daily life.
Anhedonia was associated with lower mean PA and higher mean NA across the 5-day EMA period. Anhedonia was not related to impaired behavioral reward learning, but low PA was associated with reduced nucleus accumbens response during reward anticipation and reduced medial prefrontal cortex (mPFC) response during reward outcome. Greater mean NA was associated with increased mPFC response to loss outcome.
Traditional laboratory-based measures of anhedonia were associated with lower subjective PA and higher subjective NA in youths' daily lives. Lower subjective PA and higher subjective NA were associated with decreased reward-related striatal functioning. Higher NA was also related to increased mPFC activity to loss. Collectively, these findings demonstrate that laboratory-based measures of anhedonia translate to real-world contexts and that subjective ratings of PA and NA may be associated with neural response to reward and loss.
The Hierarchical Taxonomy of Psychopathology (HiTOP) has emerged out of the quantitative approach to psychiatric nosology. This approach identifies psychopathology constructs based on patterns of co-variation among signs and symptoms. The initial HiTOP model, which was published in 2017, is based on a large literature that spans decades of research. HiTOP is a living model that undergoes revision as new data become available. Here we discuss advantages and practical considerations of using this system in psychiatric practice and research. We especially highlight limitations of HiTOP and ongoing efforts to address them. We describe differences and similarities between HiTOP and existing diagnostic systems. Next, we review the types of evidence that informed development of HiTOP, including populations in which it has been studied and data on its validity. The paper also describes how HiTOP can facilitate research on genetic and environmental causes of psychopathology as well as the search for neurobiologic mechanisms and novel treatments. Furthermore, we consider implications for public health programs and prevention of mental disorders. We also review data on clinical utility and illustrate clinical application of HiTOP. Importantly, the model is based on measures and practices that are already used widely in clinical settings. HiTOP offers a way to organize and formalize these techniques. This model already can contribute to progress in psychiatry and complement traditional nosologies. Moreover, HiTOP seeks to facilitate research on linkages between phenotypes and biological processes, which may enable construction of a system that encompasses both biomarkers and precise clinical description.
One characteristic interpretive technique in the discourse of customary international law is the identification of such norms as 'possibly emerging' or possibly in existence. Thus it is frequently asserted that a putative norm 'may' have or 'probably has' customary status. This hypothetical mode of analysis can give rise to the speculative construction of international obligations driven more by preference than by evidence. This speculative rhetorical technique is examined by reference to the account of temporal dimensions of the emergence of customary international law provided in the Chagos Archipelago Advisory Opinion of 2019. Here the International Court of Justice endeavoured to pin down the time of origin and path of evolution of a customary norm requiring territorial integrity in the context of decolonialisation as self-determination. This chapter engages with this ubiquitous characteristic of the interpretation of customary international law and argues that the accompanying opacity in relation to international legal norms – norms that are held to generate obligations – is to be deplored.
A short, effective therapy for posttraumatic stress disorder (PTSD) could decrease barriers to implementation and uptake, reduce dropout, and ameliorate distressing symptoms in military personnel and veterans. This non-inferiority RCT evaluated the efficacy of 2-week massed prolonged exposure (MPE) therapy compared to standard 10-week prolonged exposure (SPE), the current gold standard treatment, in reducing PTSD severity in both active serving and veterans in a real-world health service system.
This single-blinded multi-site non-inferiority RCT took place in 12 health clinics across Australia. The primary outcome was PTSD symptom severity measured by the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) at 12 weeks. 138 military personnel and veterans with PTSD were randomised. 71 participants were allocated to SPE, with 63 allocated to MPE.
The intention-to-treat sample included 138 participants, data were analysed for 134 participants (88.1% male, M = 46 years). The difference between the mean MPE and SPE group PTSD scores from baseline to 12 weeks-post therapy was 0.94 [95% confidence interval (CI) −4.19 to +6.07]. The upper endpoint of the 95% CI was below +7, indicating MPE was non-inferior to SPE. Significant rates of loss of PTSD diagnosis were found for both groups (MPE 53.8%, SPE 54.1%). Dropout rates were 4.8% (MPE) and 16.9% (SPE).
MPE was non-inferior to SPE in significantly reducing symptoms of PTSD. Significant reductions in symptom severity, low dropout rates, and loss of diagnosis indicate MPE is a feasible, accessible, and effective treatment. Findings demonstrate novel methods to deliver gold-standard treatments for PTSD should be routinely considered.
Wetland sediments are valuable archives of environmental change but can be challenging to date. Terrestrial macrofossils are often sparse, resulting in radiocarbon (14C) dating of less desirable organic fractions. An alternative approach for capturing changes in atmospheric 14C is the use of terrestrial microfossils. We 14C date pollen microfossils from two Australian wetland sediment sequences and compare these to ages from other sediment fractions (n = 56). For the Holocene Lake Werri Berri record, pollen 14C ages are consistent with 14C ages on bulk sediment and humic acids (n = 14), whilst Stable Polycyclic Aromatic Carbon (SPAC) 14C ages (n = 4) are significantly younger. For Welsby Lagoon, pollen concentrate 14C ages (n = 21) provide a stratigraphically coherent sequence back to 50 ka BP. 14C ages from humic acid and >100 µm fractions (n = 13) are inconsistent, and often substantially younger than pollen ages. Our comparison of Bayesian age-depth models, developed in Oxcal, Bacon and Undatable, highlight the strengths and weaknesses of the different programs for straightforward and more complex chrono-stratigraphic records. All models display broad similarities but differences in modeled age-uncertainty, particularly when age constraints are sparse. Intensive dating of wetland sequences improves the identification of outliers and generation of robust age models, regardless of program used.
In this cross-sectional survey, we assessed knowledge, attitudes and behaviors regarding operating room air-change rates, climate change, and coronavirus disease 2019 (COVID-19) pandemic implications. Climate change and healthcare pollution were considered problematic. Respondents checked air exchange rates for COVID-19 and ∼25% increased them. Respondents had difficulty completing questions concerning hospital heating, ventilation and air conditioning (HVAC) systems.
The mental health impact of the initial years of military service is an under-researched area. This study is the first to explore mental health trajectories and associated predictors in military members across the first 3–4 years of their career to provide evidence to inform early interventions.
This prospective cohort study surveyed Australian Defence personnel (n = 5329) at four time-points across their early military career. Core outcomes were psychological distress (K10+) and posttraumatic stress symptoms [four-item PTSD Checklist (PCL-4)] with intra-individual, organizational and event-related trajectory predictors. Latent class growth analyses (LCGAs) identified subgroups within the sample that followed similar longitudinal trajectories for these outcomes, while conditional LCGAs examined the variables that influenced patterns of mental health.
Three clear trajectories emerged for psychological distress: resilient (84.0%), worsening (9.6%) and recovery (6.5%). Four trajectories emerged for post-traumatic stress, including resilient (82.5%), recovery (9.6%), worsening (5.8%) and chronic subthreshold (2.3%) trajectories. Across both outcomes, prior trauma exposure alongside modifiable factors, such as maladaptive coping styles, and increased anger and sleep difficulties were associated with the worsening and chronic subthreshold trajectories, whilst members in the resilient trajectories were more likely to be male, report increased social support from family/friends and Australian Defence Force (ADF) sources, and use adaptive coping styles.
The emergence of symptoms of mental health problems occurs early in the military lifecycle for a significant proportion of individuals. Modifiable factors associated with wellbeing identified in this study are ideal targets for intervention, and should be embedded and consolidated throughout the military career.
Yarkoni's analysis clearly articulates a number of concerns limiting the generalizability and explanatory power of psychological findings, many of which are compounded in infancy research. ManyBabies addresses these concerns via a radically collaborative, large-scale and open approach to research that is grounded in theory-building, committed to diversification, and focused on understanding sources of variation.
Robotics and computer vision problems commonly require handling rigid-body motions comprising translation and rotation – together referred to as pose. In some situations, a vectorial parameterization of pose can be useful, where elements of a vector space are surjectively mapped to a matrix Lie group. For example, these vectorial representations can be employed for optimization as well as uncertainty representation on groups. The most common mapping is the matrix exponential, which maps elements of a Lie algebra onto the associated Lie group. However, this choice is not unique. It has been previously shown how to characterize all such vectorial parameterizations for SO(3), the group of rotations. Some results are also known for the group of poses, where it is possible to build a family of vectorial mappings that includes the matrix exponential as well as the Cayley transformation. We extend what is known for these pose mappings to the
$4 \times 4$
representation common in robotics and also demonstrate three different examples of the proposed pose mappings: (i) pose interpolation, (ii) pose servoing control, and (iii) pose estimation in a pointcloud alignment problem. In the pointcloud alignment problem, our results lead to a new algorithm based on the Cayley transformation, which we call CayPer.
Transfemoral venous approach is the standard method for transcatheter patent ductus arteriosus closure using the Amplatzer Piccolo patent ductus arteriosus occluder in small infants. We report a 1.4 kg infant who underwent transcatheter Piccolo patent ductus arteriosus closure. Transjugular venous approach was taken due to the unexpected finding of interrupted inferior vena cava.
This chapter chronicles the rise of Chinggis Khan and the history of the Mongols in the Middle East. The Mongol army was not a standard nomad army; it was not tribally organized, contained a number of settled soldiers, and was strictly disciplined. In describing the conquest of Iran, the chapter emphasizes the role of Iranians and the importance of local Iranian politics during the conquest and early Mongol rule. It argues that the Mongols were not ignorant of the value of city life and agriculture, and that the abuses of taxation and extortion described in the chronicles impoverished Mongol nomads as well as agriculturalists. In examining acculturation, one should look beyond the court, to the interactions of Mongols and Iranians within the army and in regional politics. Finally, the chapter considers the cultural impact of the Mongols, both their brilliant court culture and the result of their rule in the division of the Middle East into three spheres: Turkic, Arab, and Iranian.
This chapter describes the eastern steppe border of the Islamic world and the legacy of the Turk Khaghanate which had dominated the steppe. It argues that the Turks and Iranians had long been connected, even sharing some mythology. When Turkic nomads entered the Middle East, they employed the Persian bureaucrats of local dynasties. The chapter views the Seljukids as a group influenced by the steppe imperial tradition, and also well acquainted with the needs of settled populations. Following recent scholarship, it argues that despite the promotion of mamluk soldiers in the army, the Turkmen followers of the Seljuqs remained powerful and important. Continuing tribal immigration led to an increase of nomadic populations from Khorasan to Anatolia and the beginning of the Turkification of the western regions. The Seljuqids brought a significant cultural change by bringing the use of New Persian into western and central Iran as a language of administration and high culture, and introducing the use of a dual administration with a Turkic military and Persian administration. This Turco-Iranian synthesis became the court culture of Iran.
At the beginning of the nineteenth century nomads held considerable power in Iran and the Ottoman Empire. In Ottoman lands, westernizing reforms in landholding and local administration undermined tribal power and led to increasing sedentarization. In Iran, tribes and nomads remained central to the military, and retained power through World War I. In both states, the government controlled nomads by incorporating tribal leadership into government structure. New concepts of nationalism portrayed nomads as backwards and alien. World War I and the Constitutional Revolution of Iran brought an upsurge of nomad activity, but from the 1930s the Mandate powers, the Turkish Republic, and the Pahlavi dynasty of Iran worked actively to suppress nomadism. Even more important was the revolution in transportation and weaponry. The steamship, telegraph and railway replaced many caravan routes, destroying the market for camels. The machine gun and airplane made cavalry obsolete, while the truck ended the usefulness of caravans and the need for nomad guards over trade routes. Thus, nomads lost much of their usefulness to the state.
This chapter introduces the lifestyle and economy of pastoral nomadism, differentiating between the camel nomadism of the Bedouin and the nomads of the Eurasian steppe, who raised sheep, goats and horses. The definition of tribe is discussed, as are the controversies surrounding the concept. The chapter shows that nomadic and settled societies have been interdependent from the beginning of history. The development of mounted nomadism in the first millennium BC increased the power of nomads; a new type of camel saddled enabled trade across the Syrian desert and Arabian peninsula, with nomad dynasties controlling major trade routes. With the development of efficient horse riding, the Eurasian nomads became formidable mounted archers and formed powerful states.