Ultracold collisions of metastable helium atoms

We report scattering lengths for the singlet Sigma g +, triplet Sigma u + and quintet Sigma g + adiabatic molecular potentials relevant to collisions of two metastable (n=2 triplet S) helium atoms as a function of the uncertainty in these potentials. These scattering lengths are used to calculate experimentally observable scattering lengths, elastic cross sections and inelastic rates for any combination of states of the colliding atoms, at temperatures where the Wigner threshold approximation is valid.Comment: 20 pages, 8 figures, RevTeX, epsf. Small additions of tex

Transgresiones ecfrásticas: El texto y la imagen en Los herederos de Segismundo de Schmidhuber de la Mora

The nature of images in Guillermo Schmidhuber de la Mora’s award winning play Los herederos de Segismundo (1982), and the role images play in relation to the verbal medium that produces them, constitutes the object of analysis of the play as literary text and theatrical performance. The action begins 20 years after the conclusion of Calderón de la Barca’s La vida es sueño and dramatizes 30 years in the lives of Segismundo, his son Américo and their servants. The three generations of monarchs – Basilio, Segismundo and Américo – justify their stranglehold on others through capricious interpretation of visual signs – stars, icons, and sculptures. The visual forms created by the royal palace’s sculptor and the servants’ appropriation of the proscenium to address the public and comment on actions in the palace scenes are designed to alter the subordinate status of the poor, and to revise the seventeenth- century’s socio-economic and theatrical conventions, so that future generations of workers may enjoy the same opportunities previously reserved for the nobility. (GJW

Pinned Low Energy Electronic Excitation in Metal Exchanged Vanadium Oxide Nanoscrolls

We measured the optical properties of mixed valent vanadium oxide nanoscrolls and their metal exchanged derivatives in order to investigate the charge dynamics in these compounds. In contrast to the prediction of a metallic state for the metal exchanged derivatives within a rigid band model, we find that the injected charges in Mn$^{2+}$ exchanged vanadium oxide nanoscrolls are pinned. A low-energy electronic excitation associated with the pinned carriers appears in the far infrared and persists at low temperature, suggesting that the nanoscrolls are weak metals in their bulk form, dominated by inhomogeneous charge disproportionation and Madelung energy effects.Comment: 4 figure

Capturing the carer's experience: a researcher's reflections.

Aim To reflect on the methodological challenges of conducting a study exploring the effects on quality of life of being an informal carer for a person with palliative heart failure, as well as the factors that influence a carer's perception of caring. Background There are multi-faceted influences on the positive and negative effects of being a carer for a patient with palliative heart failure. By conducting a mixed methods study the aim was to examine and explore similarities and differences of the phenomenon of being a carer. Data sources Quantitative data obtained from the Family Quality of Life Questionnaire (FAMQOL), and qualitative data obtained from 14 interviews with informal carers of patients living with palliative heart failure. Review methods The study was conducted as part of a PhD, University of Sheffield, and the supervisory team reviewed the research process throughout the study. Discussion The study had a two-phase sequential mixed methods design. A sample of carers was recruited from heart failure nurse service caseloads in a UK urban setting. Carers were invited to complete the Family Quality of Life Questionnaire, a tool developed for carers of patients with heart failure. Participants were also asked to provide contact details if they were willing to be interviewed for the second phase of the study. Conclusion The study highlights important methodological considerations for recruiting carers. As the intention was to begin the analysis of the questionnaires before beginning the second phase of the study, the researcher was compelled to consider how integration was maintained and how to improve access to carers for research. Implications for practice The complexities associated with the population in this study led the researcher to use a pragmatic design to address research questions. When reflecting on the research and the challenges associated with recruiting to the quantitative phase of the study, the researcher used an iterative approach to meet the unfolding complexities. Such an approach could prove beneficial for mixed methods studies that aim to engage with hard to reach populations

Symmetry improvement of 3PI effective actions for O(N) scalar field theory

[Abridged] n-Particle Irreducible Effective Actions ($n$PIEA) are a powerful tool for extracting non-perturbative and non-equilibrium physics from quantum field theories. Unfortunately, practical truncations of $n$PIEA can unphysically violate symmetries. Pilaftsis and Teresi (PT) addressed this by introducing a "symmetry improvement" scheme in the context of the 2PIEA for an O(2) scalar theory, ensuring that the Goldstone boson is massless in the broken symmetry phase [A. Pilaftsis and D. Teresi, Nuc.Phys. B 874, 2 (2013), pp. 594--619]. We extend this by introducing a symmetry improved 3PIEA for O(N) theories, for which the basic variables are the 1-, 2- and 3-point correlation functions. This requires the imposition of a Ward identity involving the 3-point function. The method leads to an infinity of physically distinct schemes, though an analogue of d'Alembert's principle is used to single out a unique scheme. The standard equivalence hierarchy of $n$PIEA no longer holds with symmetry improvement and we investigate the difference between the symmetry improved 3PIEA and 2PIEA. We present renormalized equations of motion and counter-terms for 2 and 3 loop truncations of the effective action, leaving their numerical solution to future work. We solve the Hartree-Fock approximation and find that our method achieves a middle ground between the unimproved 2PIEA and PT methods. The phase transition predicted by our method is weakly first order and the Goldstone theorem is satisfied. We also show that, in contrast to PT, the symmetry improved 3PIEA at 2 loops does not predict the correct Higgs decay rate, but does at 3 loops. These results suggest that symmetry improvement should not be applied to $n$PIEA truncated to $<n$ loops. We also show that symmetry improvement is compatible with the Coleman-Mermin-Wagner theorem, a check on the consistency of the formalism.Comment: 27 pages, 15 figures, 2 supplemental Mathematica notebooks. REVTeX 4.1 with amsmath. Updated with minor corrections. Accepted for publication in Phys. Rev.

Factorization fits to charmless strangeless B decays

We present fits to charmless strangeless hadronic B decay data for mean branching ratios and CP-violating asymmetries using the QCD factorization model of Beneke et al. Apart from one CP-violating parameter, the model gives a very good representation of 26 measured data. We find the CKM angle alpha = (93.5 +/- 8.4 -1.3) degrees and to be quite stable to plausible "charming penguin" corrections.Comment: 4 pages, LaTeX, Minor changes to text, references adde

Evaluation of the Ecosystem Services of the Central Marsh in Southern Iraq

Ecosystems provide humans with services that include benefits from food, fresh water, climate regulation, and socio-economic assets. The Mesopotamian marshlands are among the largest wetlands in the Middle East and they provide various benefits. However, ecosystem services of the Marshlands are consistently undervalued in national economic analysis and decision making. This study focusses on the Central Marshes, the first National Park in Iraq, and is the first attempt at valuing a series of ecosystem services from a valuable natural ecosystem in Iraq. We adopted the Toolkit for Ecosystem Services Site-Based Assessment (TESSA) for the determination of biophysical and economic values of services at the site level. Data on key ecosystem services (as determined by 30 interviews with residents of the Marshes) included the trading of fish, harvested plants, water buffalo milk, and fodder were collected across six months in 2014. We valued the ecosystem services within the CM (40,000 ha) over a 6-month period to have a total value of 860,078.23 USD. This estimated total value was the sum of 86,637.25 USD from harvested plants, 551,334.80 USD from trading fish, 167, 303.70 USD from trading water buffalo milk, and 54,804.00 USD from trading fodder. The average income per individual in Iraq in 2014 was 6720 USD (World Bank data - https://data.worldbank.org/country/iraq): thus, the CM provided an average salary for 256 people. Our results provided greater understanding of the ecosystem services contributed by the Central Marshes and has highlighted the crucial role of nature in supporting sustainable well-being for humans living in the area. In addition, the results can be used to enhance local policy, to aid management plans of the National park, and to estimate lost and damage that could result from impact of climate change on the area

Ultracold collisions in tight harmonic traps: Quantum defect model and application to metastable helium atoms

We analyze a system of two colliding ultracold atoms under strong harmonic confinement from the viewpoint of quantum defect theory and formulate a generalized self-consistent method for determining the allowed energies. We also present two highly efficient computational methods for determining the bound state energies and eigenfunctions of such systems. The perturbed harmonic oscillator problem is characterized by a long asymptotic region beyond the effective range of the interatomic potential. The first method, which is based on quantum defect theory and is an adaptation of a technique developed by one of the authors (GP) for highly excited states in a modified Coulomb potential, is very efficient for integrating through this outer region. The second method is a direct numerical solution of the radial Schr\"{o}dinger equation using a discrete variable representation of the kinetic energy operator and a scaled radial coordinate grid. The methods are applied to the case of trapped spin-polarized metastable helium atoms. The calculated eigenvalues agree very closely for the two methods, and with those computed self-consistently using the generalized self-consistent method.Comment: 11 pages,REVTEX, text substantially revised, title modifie

Pollution threatens water quality in the Central Marshes of Southern Iraq

تلوث المياه مشكلة يمكن أن تتفاقم بسبب الجفاف مع زيادة تراكيز المواد غير المرغوب فيها. توفر الاهوار الطبيعية إمكانية تحسين جودة المياه وهنا نقدم أدلة على هذه الخدمة بناءً على تدفق المياه من نهر الفرات (الذي عانى من انخفاض كبير في التدفق) إلى الأهوار في جنوب العراق. تم إنشاء سدة ترابية في عام 2010 على نهر الفرات لمنع المياه التي يقل ارتفاعها عن 1.7 متر من المرور من محافظة ذي قار (الجبايش) إلى محافظة البصرة (المدَينه) كاستجابة للجفاف الشديد الذي واجه المنطقة في عامي 2009 و 2010. ونتيجة لذلك ، أصبحت الاهوار الوسطى في الجبايش موقعا نهائيا (بدون منفذ) الى كل مياه نهر الفرات التي تاتي من غرب العراق محملة بمختلف الملوثات والنفايات الزراعية. تم اختبار قدرة الاهوار الوسطى على العمل كبالوعة لتقليل تراكم العناصر الغذائية (NO2 ، NO3 ، PO4) ، والملوحة ، والأيونات الرئيسة ، والمعادن الثقيلة (Cu ، Ni ، Pb ، Cd ، Zn) في نهر الفرات. قسمت منطقة الدراسة إلى أربع مناطق أفقية (النهر وثلاث مناطق داخل الهور) وأجريت ثمانية مسوحات ميدانية من تشرين الثاني 2013 إلى حزيران 2014 لجمع عينات المياه باستخدام منهجية الخط المستقيم (transect line methodology). كانت الملوحة والأيونات الرئيسية أعلى بشكل معنوي داخل الهور مقارنة بالنهر. ومع ذلك ، لم يتم العثور على اختلافات بين قيم المغذيات في النهر والهور مما يشير إلى أن دور الهور للعمل كبالوعة لهذه المواد كان محدودا  وان تراكم الملوثات وتركيزها كان اكثر في داخل الهور منه الى المناطق القريبة للنهر. لذلك فإن التراكم طويل الأمد يشكل تحديًا كبيرًا يواجه الهور في ظل ظروف شحة المياه في نهر الفرات ، وهذا يتطلب اهتمامًا عاجلاً ، خاصة بالنظر إلى مكانة الموقع كموقع للتراث العالمي (لخدمات النظم الطبيعية المقدمة للسكان المحليين) وكمنطقة تنوع بيولوجي مهمة. ملف ملحقWater pollution is an issue that can be exacerbated by drought as increased concentrations of unwanted substances are a consequence of lower water levels. Polluted water that flows into natural marshlands leads to the deposition of pollutants in the interior of the marsh. Here we present evidence that the interior of the Central Marsh (CM) in southern Iraq suffers from higher levels of pollution than areas closer to the source of water entering the marsh (the Euphrates River). A 1.7m embankment that halts the flow of the Euphrates is only infrequently breached and so the CM is effectively the terminal destination of the waters (and their associated pollutants and agricultural waste) flowing from the West of Iraq. A range of water quality metrics were measured where the Euphrates enters the CM and at increasing distances into the interior of the CM. The following measures were taken:  NO2, NO3, PO4 , Salinity, Major ions, and Heavy Metals (Cu, Ni, Pb, Cd, Zn). The area of study was divided into four horizontal zones (the river and three zones inside the marsh) and eight field surveys were carried out from November 2013 to June 2014 to collect water samples by using a transect line methodology.  Salinity and major ions (Na, K, Cl, Ca, and Mg) were significantly higher inside the marsh compared with levels in the river water immediately before it entered the CM.  These findings indicate  the increased risk of these pollutants to humans and wildlife living in and using the CM.  This issue  requires urgent attention, especially to the status of the CM as a World Heritage site (for the ecosystem services provided to local people) as an Important Biodiversity Area. The reported declines in water quantity in the Euphrates over recent decades will likely further exacerbate the problems we report. Supplement fil