Miracle-dz/UniFAR-FTUs huggingface dataset:
Production and oscillations of a Bose Einstein condensate on an atom chip

This thesis describes production of and experiments with a Bose-Einstein condensate of approximately 2 × 104 87Rb atoms, trapped at the surface of an atom chip. In the first half of this thesis I describe the process of trapping and cooling the atomic vapour close to the surface of an atom chip. This process, which cools the vapour by over 9 orders of magnitude, involves a highly complex sequence of events which I implemented and optimised over the first two years of my PhD. In the early stages of this process, the atomic vapour is laser cooled and magneto-optically trapped. The vapour is then transferred to a highly elongated magnetic trap produced by high field gradients a few hundred microns from the surface of the atom chip. Here the vapour is evaporatively cooled to below the transition temperature where a Bose-Einstein condensate emerges. A simple existing analytic model of evaporative cooling is extended in this work to account for the shape of our highly elongated trap. Predictions of this model are presented here along with experimental observations with which it has good agreement. The second part of my thesis investigates some of the characteristics of the condensate, and dynamics of its low energy collective oscillations in the trap, based on experimental measurements taken in the final 18 months of my PhD. In particular, measurements taken of the centre of mass oscillations of the condensate along the long axis of the trap are presented. In the zero temperature limit the condensate is expected to behave as a perfect superfluid, and these low energy oscillations should go undamped. However, at finite temperature where not all atoms in the gas are condensed, damping is observed. In our experiment significant damping is found with an 1/e decay rate which varies between 2 s−1 and 8 s−1, depending on the fraction of non-condensed atoms in the gas. A finite temperature formalism is then used to describe the likely damping mechanism Landau damping. We use a simple model of this formalism which estimates the temperature dependence of the damping rate γ(T ), but find this gives a significant overestimation of the rates we measure. However, we argue that a straightforward adaptation to this model reduces the predicted damping rate significantly, and suggests a functional form of γ(T ) that is in much better agreement with our experimental measurements.
Constraining the role of novae as progenitors of type Ia supernovae

(Abridged) White dwarfs (WDs) undergoing unstable nuclear burning on their surfaces, resulting in the nova phenomenon, have been considered as one of the prospective candidates for the still elusive progenitors of SNeIa. We propose that statistics of novae in nearby galaxies may be a powerful tool to gauge the role of such systems in producing SNeIa. Using multicycle nova evolutionary models, we compute the number and temporal distribution of novae that would be produced by a typical (unstably burning) SNIa progenitor before reaching the Chandrasekhar mass limit (M_ch) and exploding. Combined with the observed nova rates, this can be used to constrain the maximal contribution of the nova channel to the SNIa rate in nearby galaxies. The M31 nova rate measured by the POINT-AGAPE survey is 65/yr. Assuming that all these novae will reach M_ch, we obtain the maximal SNIa rate novae may produce to be (1-5)x10^-4/yr. This constrains the overall contribution of the nova channel to the SNIa rate in M31 at 10^3xf per yr, where f is the fraction of SNeIa which accreted in the unstable nuclear burning regime while accumulating the final ~0. 1M_sun before the SNIa explosion.
Short-term soil physical responses to grazing and cover crops in an integrated crop-livestock agroecosystem

Cover crops (CCs) and grazing play critical roles in the successful implementation of integrated crop-livestock systems (ICLSs) because they can have a direct impact on soil functions. The present study was conducted to assess the short-term impacts of CCs and grazing on soil physical and hydrological properties. Two sites (Northern-Brookings and Northwestern-Brookings) were established in 2016 and 2017, respectively, in South Dakota, United States. The specific objective was to evaluate the impact of CCs and grazed CCs under oat (Avena sativa L.)/CCs–corn (Zea mays L.) rotation on soil physical and hydrological properties. Study treatments included (1) legume-dominated CC (LdC), (2) cattle-grazed LdC (LdC+G), (3) grass-dominated CC (GdC), (4) cattle-grazed GdC (GdC+G), and (5) no CC and no grazing (NC). After two to three years of management, CCs and grazing did not impact soil organic carbon (SOC) and total nitrogen (TN) stocks, and their values at approximate depth of 0 to 20 cm ranged from 50.9 to 60.6 Mg C ha−1 and 3.65 to 4.92 Mg N ha−1, respectively, among the treatments at each site. Cover crops decreased soil bulk density (ρb) at 0 to 10 cm and 10 to 20 cm depths and, in general, increased soil water retention (SWR), total porosity, and quasi-steady infiltration rate (Northern-Brookings only) compared to the NC. Cattle grazing of CC generally increased ρb and reduced SWR and porosity compared with the ungrazed CC but not to the often-perceived detrimental levels. Our findings showed that CCs can improve some aspects of soil physical health in the short term and that grazing of CCs and crop residue did not cause substantial physical damage to the soil under the conditions of these experiments.
A New Approach on the Seating Couples Problem

A king invites n couples to sit around a round table with 2n+1 seats. For each couple, the king decides a prescribed distance d between 1 and n which the two spouses have to be seated from each other (distance d means that they are separated by exactly d-1 chairs). We will show that there is a solution for every choice of the distances if and only if 2n+1 is a prime number, using a theorem known as Combinatorial Nullstellensatz.
Introduction: social protection in the Western Balkans

Abstract This introductory essay situates the papers in this Thematic Section within the background of social policy development in the Western Balkans during the long period of transition following the break-up of former Yugoslavia. We identify three stages of transformation of social protection policies. The first, in the 1990s, was characterised by a continuation of the Yugoslav legacy of social insurance, while many work-based benefits were lost during privatisation. In the second stage, international institutions promoted individualised social protection policies, taken up in some countries but avoided in others. In the third phase, EU influence on social policies accompanied the prolonged EU accession process, with an emphasis on the introduction of work-care policies, early childhood education and the remediation of in-work poverty. The four papers address these issues in greater detail and provide a basis for re-evaluating progress with social protection policies in the Western Balkans in the future.
The dynamics of a rigid inverted flag

Abstract An ‘inverted flag’ – a flexible plate clamped at its trailing edge – undergoes large-amplitude flow-induced flapping when immersed in a uniform and steady flow. Here, we report direct numerical simulations of a related single degree-of-freedom mechanical system: a rigid plate attached at its trailing edge to a torsional spring. This system is termed a ‘rigid inverted flag’ and exhibits the dynamical states reported for the (flexible) inverted flag, with additional behaviour. This finding shows that the flapping dynamics of inverted flags is not reliant on their continuous flexibility, i.e. many degrees of freedom. The rigid inverted flag exhibits additional, novel states including a heteroclinic-type orbit that results in small-amplitude flapping, and a number of chaotic large-amplitude flapping regimes. We show that the various routes to chaos are driven by a series of periodic states, including at least two which are subharmonic. The instability and competition between these periodic states lead to chaos via type-I intermittency, mode competition and mode locking. The rigid inverted flag allows these periodic states and their subsequent interaction to be explained simply: they arise from an interaction between a preferred vortex shedding frequency and a single natural frequency of the structure. The dynamics of rigid inverted flags is yet to be studied experimentally, and this numerical study provides impetus for such future work.
Combinatorics of line arrangements and dynamics of polynomial vector fields

Let $\mathcal{A}$ be a real line arrangement and $\mathcal{D}(\mathcal{A})$ the module of $\mathcal{A}$--derivations. First, we give a dynamical interpretation of $\mathcal{D}(\mathcal{A})$ as the set of polynomial vector fields which posses $\mathcal{A}$ as invariant set. We characterize polynomial vector fields having an infinite number of invariant lines. Then we prove that the minimal degree of polynomial vector fields fixing only a finite set of lines in $\mathcal{D}(\mathcal{A})$ is not determined by the combinatorics of $\mathcal{A}$.
Skyrmions and the α-particle model of nuclei

We compute new solutions of the Skyrme model with massive pions. Concentrating on baryon numbers which are multiples of four, we find low-energy Skyrmion solutions that are composed of charge four subunits, as in the α-particle model of nuclei. We summarize our current understanding of these solutions, and discuss their relationship to configurations in the α-particle model.
The physics and physical conditions of quasar outflows

We describe two studies designed to characterize the total column densities, kinetic energies, and acceleration physics of broad absorption line (BAL) outflows in quasars. The first study uses new Chandra X-ray and ground-based rest-frame UV observations of 7 quasars with mini-BALs at extreme high speeds, in the range 0.1c to 0.2c, to test the idea that strong radiative shielding is needed to moderate the mini-BAL ionizations and facilitate their acceleration to extreme speeds. We find that the X-ray absorption is weak or absent, with generally N_H<few x 10^22 mc^-2, and that radiative shielding is not important. We argue that the mini-BAL ionizations are controlled, instead, by high gas densities of order n_H ~ 4 x 10^8 cm^-3 in small outflow substructures. If we conservatively assume that the total column density in the mini-BAL gas is N_H<10^22 cm^-2, covering>15% of the UV continuum source along our lines of sight (based on measured line depths), then the radial thickness of these outflows is only Delta_R<3 x 10^13 cm and their transverse size is>8 x 10^15 cm. Thus the outflow regions have the shape of very thin"pancakes"viewed face-on, or they occupy larger volumes like a spray of dense cloudlets with a very small volume filling factor. We speculate that this situation (with ineffective shielding and small dense outflow substructures) applies to most quasar outflows, including BALs. Our second study focuses from BALs of low-abundance ions, mainly PV 1118,1128 A, whose significant strengths imply large column densities, N_H>10^22 cm^-2, that can further challenge models of the outflow acceleration. In spite of the difficulties of finding this line in the Ly-alpha forest, a search through the SDSS DR9 quasar catalog reveals>50 BAL sources at redshifts z>2.3 with strong PV BALs, which we are now using to characterize the general properties of high-column outflows.
A UNIVERSAL, TURBULENCE-REGULATED STAR FORMATION LAW: FROM MILKY WAY CLOUDS TO HIGH-REDSHIFT DISK AND STARBURST GALAXIES

While the star formation rate (SFR) of molecular clouds and galaxies is key in understanding galaxy evolution, the physical processes that determine the SFR remain unclear. This uncertainty about the underlying physics has resulted in various different star formation (SF) laws, all having substantial intrinsic scatter. Extending upon previous works that define the column density of star formation ( &Sgr; SFR ? > ) by the gas column density ( &Sgr; gas ? > ), we develop a new universal SF law based on the multi-freefall prescription of gas. This new SF law relies predominantly on the probability density function and on the sonic Mach number of the turbulence in the star-forming clouds. By doing so we derive a relation where the SFR correlates with the molecular gas mass per multi-freefall time, whereas previous models had used the average, single-freefall time. We define a new quantity called maximum (multi-freefall) gas consumption rate (MGCR) and show that the actual SFR is only about 0.4% of this maximum possible SFR, confirming the observed low efficiency of SF. We show that placing observations in this new framework ( &Sgr; SFR ? > versus MGCR) yields a significantly improved correlation with 3–4 times reduced scatter compared to previous SF laws and a goodness-of-fit parameter R 2 = 0.97 ? > . By inverting our new relationship, we provide sonic Mach number predictions for kiloparsec-scale observations of Local Group galaxies as well as unresolved observations of local and high-redshift disk and starburst galaxies that do not have independent, reliable estimates for the turbulent cloud Mach number.
Decision Memo for Magnetic Resonance Imaging (MRI) (CAG-00399R4)

The Centers for Medicare & Medicaid Services (CMS) is reconsidering our national coverage determination at section 220.2 of the Medicare National Coverage Determinations Manual, specifically the Coverage with Evidence Development (CED) requirement (section 220.2(C)(1)). We determined that the evidence is sufficient to conclude that magnetic resonance imaging (MRI) for Medicare beneficiaries with an implanted pacemaker (PM), implantable cardioverter defibrillator (ICD), cardiac resynchronization therapy pacemaker (CRT-P), or cardiac resynchronization therapy defibrillator (CRT-D) is reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member under section 1862(a)(1)(A) of the Social Security Act under certain circumstances. Thus, we will modify our national coverage determination to eliminate the collection of additional information under the Coverage with Evidence Development paradigm under section 1862(a)(1)(E) of the Social Security Act.
National Security in Nairobi County, Kenya

Maintenance of security and good order for the citizens, had traditionally been undertaken by the state. However, non-state actors have come up to offer security to those who can afford to pay for it. And this is the liberalists view of the provision of security that, the pursuance of security can be achieved with the involvement of other actors offering the same. Despite this development, few studies have examined commercialized security industry services on national security in Kenya. Using Security Governance theory and Network Analysis theory, this study sought to understand the topic. The study took on a cross sectional survey design, and was carried out in Nairobi with the adult residents as the target population. A multistage sampling technique was employed to obtain the respondents. Questionnaires, scheduled interviews and structured observation were used to collect data. The Statistical Package for Social Sciences (SPSS version 25, 2017) was used in data management and analysis. The results demonstrate that (1) Manned guarding significantly contributes to the 26 % of outcome of the commercialized (cid:3)(cid:17)(cid:19)(cid:22)(cid:25)(cid:15)(cid:3) (cid:21) (cid:3) (cid:3)(cid:17)(cid:19)(cid:27)(cid:23)(cid:15)(cid:3)3(cid:3)(cid:31)(cid:3) (cid:3) . 103 although it was not significant. The study concluded that, commercialized security though motivated by profit making plays a significant role that enhances state capacity in provision of security as well as contributes to safety of citizens. Thus the study recommended that, there should be efforts to increase the usage of commercialized security investigation service. It is expected that the findings of this research will provide data that can be used to inform policy and practice amongst commercial security providers to increase their impact on national security in Kenya. The data can also stimulate the academic community towards more research in the field.
Middle East Journal of TEFL Teachers' Electronic Feedback on First Year Students' EFL Writing at a Saudi University: Issues and Implications

ELT, ESP, and Applied Linguistics. Abstract This study explores the experiences of English language teachers (ELTs) in providing written feedback on their students' writing via a digital platform in their first year at a Saudi university. The purpose of this exploratory study is to identify: (a) the nature of the electronic feedback that ELTs provide on students' writing; i.e. positive vs negative, (b) the focus of ELTs' e-feedback, (c) the amount of ELTs' feedback. 120 First Year College students and four EFL teachers participated in this study. The e-feedback submitted by these four ELTs was qualitatively analyzed. The analysis indicates that most of the ELTs' e-feedback were general and brief. In addition, the focus of their e-feedback was mainly on grammar and vocabulary. Interestingly, the ELTs tend to give positive e-feedback. The study concludes with providing some implications for effective feedback.
Spatial characteristics and kinematics of floodplain aggradation cycles in 7 the lower Eocene Bighorn Basin, Wyoming, USA

: 19 Interaction of allogenic and autogenic forcing in building alluvial stratigraphy remains a complex 20 subject that is critical for paleoenvironmental and paleoclimate reconstruction and subsurface rock 21 property prediction. Autogenic processes may act at similar vertical and lateral scales at which 22 astronomical climate forcing drives alluvial stratigraphic deposition, making it difficult to disentangle 23 these drivers in the rock record. In the lower Eocene Willwood Formation, Bighorn Basin, Wyoming, 24 USA, a lot of evidence has been gathered to relate dominant floodplain aggradation cycles to precession- 25 scale climate change. Previous studies have analyzed these cycles to be consistently developed in 26 multiple areas of the basin of different ages and, in one study, in two parallel one-dimensional (1-D) 27 occurring at around 7.0 m thickness, which is probably why autogenic and allogenic drivers can be 50 disentangled in this series. 51
NorDiNa – Nordic Studies in Science Education

meaning-making of a model through trans-formations and narratives in lower secondary school” with investigations of 11–12-year-old Norwegian students´ narratives over time. The students imaging living in a “Bottle Garden”, a sealed micro-ecosystem often used in school settings. The analysis focused on making inspired on findings activates their approach if from different perspectives and to understand the inherent complexity. The results also suggest that the students developed their critical thinking skills and awareness as consumers. Furthermore, students report to have developed an interest in environmental issues and a feeling that they have opportunities to make a difference. These aspects constitute important conditions for active citizenship and informed decision-making. Students – The Importance of Social Relations” explores the expectations and experiences of first-year biotechnology students. The analysis builds on video-diaries, interviews and open-ended survey responses. The findings indicate that the students were mainly challenged by the organisational dimension (lack of clarity in goals and course organisation). The social relations to peers were pivotal for the students as learning support when managing the challenges and decoding expectations, but also for keeping up the motivation. The authors argue that in order to support the students’ sense of belonging and their academic achievements, the study programmes should facili-tate the formation of social networks and consider the course organisation and management. is a collaboration between teachers and researchers in a preschool context. The aim of the paper is to contribute knowledge on how aesthetics and explorative teaching is used in science education in preschool with children aged 3-5 years. The data analysed in this study is interactive logbooks that were used as communicative tools throughout a five-month-long project about soil and earthworms. The thematic analysis reveals that different aesthetic and multimodal experiences are expressed during the project: for example mo-tion, drawing, communicative and verbal expressions and close observations. The logbooks show the children’s engagement, curiosity and sense of fascination. Furthermore, the preschool teachers make use of the children’s expressions of engagement and base the following activities on the children’s interests.
Exploring the Relationship between Leisure Activity Engagement and Happiness in China based on CGSS 2013-2018 Data

Based on the Chinese General Social Survey database (2013-2018), this paper investigates the relationship between leisure activity engagement and happiness in China when the standard correlates of happiness are held as controls. Fixed effect models indicate that leisure activity engagement is positively related to respondents’ happiness, and respondents who are female, married, better educated, higher in personal annual income, owned more houses report higher level of happiness. We further investigate the relationship between engaging in 12 types of leisure activities and happiness. Except watching sports, the more frequently respondents watch TV/DVDs, going out for movies, shopping, reading books/newspapers/magazines, attending culture events, meeting relatives who don’t live together, meeting friends, listening to music at home, participating in exercises, making handicrafts and surfing online, the higher level of happiness that respondents report. Overall, this study provides empirical finding to verify the contribution of leisure activity engagement to Chinese people’s happiness, which has implications to making China’s leisure-related policy and industry practices.
Influence of Work Environment and Work Characteristics on Turnover Intention System with Mediation Role of Work Engagement

of Work Work Abstract The millennial generation currently dominates human resources in the company. Millennial generation employees have many advantages, but millennials are considered less committed to their work, so they are synonymous with high turnover intentions. The research was conducted to know the effect of the work environment and job characteristics on the turnover intention with the mediating role of work engagement in millennial generation employees, work environment, and job characteristics as independent variables. Turnover intention is the dependent variable, and work engagement is a mediating variable. This study uses a survey method by distributing questionnaires where the respondents used 204 employees in the millennial generation with domiciles in the West Jakarta area. Then, the data was processed using the SEM-PLS method. The results showed that the work environment hurt turnover intention. Job characteristics do not affect turnover intention. Job engagement hurts turnover intention. The work environment has a positive effect on work engagement. Work characteristics have a positive effect on work engagement. Furthermore, work engagement mediates the relationship between the work environment and turnover intention. Job engagement also mediates the relationship between job characteristics and turnover intention.