Designs of magnetic atom-trap lattices for quantum simulation experiments

We have designed and realized magnetic trapping geometries for ultracold atoms based on permanent magnetic films. Magnetic chip based experiments give a high level of control over trap barriers and geometric boundaries in a compact experimental setup. These structures can be used to study quantum spin physics in a wide range of energies and length scales. By introducing defects into a triangular lattice, kagome and hexagonal lattice structures can be created. Rectangular lattices and (quasi-)one-dimensional structures such as ladders and diamond chain trapping potentials have also been created. Quantum spin models can be studied in all these geometries with Rydberg atoms, which allow for controlled interactions over several micrometers. We also present some nonperiodic geometries where the length scales of the traps are varied over a wide range. These tapered structures offer another way to transport large numbers of atoms adiabatically into subwavelength traps and back.Comment: 9 pages, 10 figure

Measuring very negative water potentials with polymer tensiometers: principles, performance and applications

In recent years, a polymer tensiometer (POT) was developed and tested to directly measure matric potentials in dry soils. By extending the measurement range to wilting point (a 20-fold increase compared to conventional, water-filled tensiometers), a myriad of previously unapproachable research questions are now open to experimental exploration. Furthermore, the instrument may well allow the development of more water-efficient irrigation strategies by recording water potential rather than soil water content. The principle of the sensor is to fill it with a polymer solution instead of water, thereby building up osmotic pressure inside the sensor. A high-quality ceramic allows the exchange of water with the soil while retaining the polymer. The ceramic has pores sufficiently small to remain saturated even under very negative matric potentials. Installing the sensor in an unsaturated soil causes the high pressure of the polymer solution to drop as the water potentials in the soil and in the POT equilibrate. As long as the pressure inside the polymer chamber remains sufficiently large to prevent cavitation, the sensor will function properly. If the osmotic potential in the polymer chamber can produce a pressure of approximately 2.0 MPa when the sensor is placed in water, proper readings down to wilting point are secured. Various tests in disturbed soil, including an experiment with root water uptake, demonstrate the operation and performance of the new polymer tensiometer and illustrate how processes such as root water uptake can be studied in more detail than before. The paper discusses the available data and explores the long term perspectives offered by the instrument

Twistor theory on a finite graph

We show how the description of a shear-free ray congruence in Minkowski space as an evolving family of semi-conformal mappings can naturally be formulated on a finite graph. For this, we introduce the notion of holomorphic function on a graph. On a regular coloured graph of degree three, we recover the space-time picture. In the spirit of twistor theory, where a light ray is the more fundamental object from which space-time points should be derived, the line graph, whose points are the edges of the original graph, should be considered as the basic object. The Penrose twistor correspondence is discussed in this context

Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately −0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed polymer tensiometers (POTs) are able to directly measure soil matric potentials until the theoretical wilting point (−1.6 MPa). By minimizing the volume of polymer solution inside the POT while maximizing the ceramic area in contact with that polymer solution, response times drop to acceptable ranges for laboratory and field conditions. Contact with the soil is drastically improved with the use of cone-shaped solid ceramics instead of flat ceramics. The comparison between measured potentials by polymer tensiometers and indirectly obtained potentials with time domain reflectometry highlights the risk of using the latter method at low water contents. By combining POT and time domain reflectometry readings in situ moisture retention curves can be measured over the range permitted by the measurement range of both POT and time domain reflectometry

The (co-)occurrence of problematic video gaming, substance use, and psychosocial problems in adolescents

Aims. The current study explored the nature of problematic (addictive) video gaming and the association with game type, psychosocial health, and substance use. Methods. Data were collected using a paper and pencil survey in the classroom setting. Three samples were aggregated to achieve a total sample of 8478 unique adolescents. Scales included measures of game use, game type, the Video game Addiction Test (VAT), depressive mood, negative self-esteem, loneliness, social anxiety, education performance, and use of cannabis, alcohol and nicotine (smoking). Results. Findings confirmed problematic gaming is most common amongst adolescent gamers who play multiplayer online games. Boys (60%) were more likely to play online games than girls (14%) and problematic gamers were more likely to be boys (5%) than girls (1%). High problematic gamers showed higher scores on depressive mood, loneliness, social anxiety, negative self-esteem, and self-reported lower school performance. Nicotine, alcohol, and cannabis using boys were almost twice more likely to report high PVG than non-users. Conclusions. It appears that online gaming in general is not necessarily associated with problems. However, problematic gamers do seem to play online games more often, and a small subgroup of gamers – specifically boys – showed lower psychosocial functioning and lower grades. Moreover, associations with alcohol, nicotine, and cannabis use are found. It would appear that problematic gaming is an undesirable problem for a small subgroup of gamers. The findings encourage further exploration of the role of psychoactive substance use in problematic gaming

Diagnostic accuracy of the Dutch version of the 4AT for delirium detection in a mixed patient population and setting

BACKGROUND: Delirium is an acute disturbance in attention, awareness and cognition. Immediate detection in older adults is recommended because delirium is associated with adverse outcomes. The 4 'A's Test (4AT) is a short screening instrument for delirium. The aim of this study is to evaluate diagnostic accuracy of the Dutch version of the screening tool 4AT for delirium detection in different settings.METHODS: Prospective observational study conducted in two hospitals in patients aged ≥ 65 years in geriatric wards and the Emergency Department (ED). Each participant underwent two assessments; the index test 4AT, followed by the reference standard for delirium performed by a geriatric care specialist. The reference standard delirium is according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria.RESULTS: A total of 71 geriatric inpatients and 49 older ED patients were included. The prevalence of delirium was 11.6% in the acute geriatric ward and 6.1% in the ED. The sensitivity and specificity of the 4AT in the acute geriatric ward were 0.88 and 0.69, respectively. In the ED, the sensitivity and specificity were 0.67 and 0.83, respectively. The area under the receiver operating characteristic curve was 0.80 for the acute geriatric ward setting and 0.74 for the ED setting.CONCLUSION: The Dutch version of the 4AT is a reliable screening tool for delirium detection in both acute geriatric wards and ED. Due to its brevity and practicality (i.e., no special training is required to administer the tool), it is useful in clinical practice.</p

Screening instruments for cognitive impairment in older patients in the Emergency Department:A systematic review and meta-analysis

Background: Cognitive impairment is highly prevalent among older patients attending the Emergency Department (ED) and is associated with adverse outcomes. Methods: we conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of cognitive screening instruments to rule out cognitive impairment in older patients in the ED. A comprehensive literature search was performed in MEDLINE, EMBASE, CINAHL and CENTRAL. A risk of bias assessment using QUADAS-2 was performed. Results: 23 articles, examining 18 different index tests were included. Only seven index tests could be included in the meta-analysis. For ruling out cognitive impairment irrespective of aetiology, Ottawa 3 Day Year (O3DY) (pooled sensitivity 0.90; (95% CI) 0.71-0.97) had the highest sensitivity. Fourteen articles focused on screening for cognitive impairment specifically caused by delirium. For ruling out delirium, the 4 A's Test (4AT) showed highest sensitivity (pooled sensitivity 0.87, 95% confidence interval (95% CI) 0.74-0.94). Conclusions: High clinical and methodological heterogeneity was found between included studies. Therefore, it is a challenge to recommend one diagnostic test for use as a screening instrument for cognitive impairment in the ED. The 4AT and O3DY seem most promising for ruling out cognitive impairment in older patients attending the ED. The review protocol was registered in PROSPERO (CRD42018082509)

Morphobathymetry and formation processes of sediment waves in the Gulf of Valencia continental slope (NW Mediterranean)

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