1,310 research outputs found
Diffraction of a released bose-einstein condensate by a pulsed standing light wave
We study the diffraction of a released sodium Bose-Einstein condensate by a pulsed standing light wave. The width of the momentum distribution of the diffracted atoms exhibits strong oscillations as a function of the pulse duration, corresponding to periodic focusing and collimation of the condensate inside the standing light wave. Applications of this thick grating regime of diffraction to atom interferometry are discussed
On Parity-Violating Three-Nucleon Interactions and the Predictive Power of Few-Nucleon EFT at Very Low Energies
We address the typical strengths of hadronic parity-violating three-nucleon
interactions in "pion-less" Effective Field Theory in the nucleon-deuteron
(iso-doublet) system. By analysing the superficial degree of divergence of loop
diagrams, we conclude that no such interactions are needed at leading order.
The only two linearly independent parity-violating three-nucleon structures
with one derivative mix two-S and two-P-half waves with iso-spin transitions
Delta I = 0 or 1. Due to their structure, they cannot absorb any divergence
ostensibly appearing at next-to-leading order. This observation is based on the
approximate realisation of Wigner's combined SU(4) spin-isospin symmetry in the
two-nucleon system, even when effective-range corrections are included.
Parity-violating three-nucleon interactions thus only appear beyond
next-to-leading order. This guarantees renormalisability of the theory to that
order without introducing new, unknown coupling constants and allows the direct
extraction of parity-violating two-nucleon interactions from three-nucleon
experiments.Comment: 20 pages LaTeX2e, including 9 figures as .eps file embedded with
includegraphicx. Minor modifications and stylistic corrections. Version
accepted for publication in Eur. Phys. J.
Neutral and cationic half-sandwich arene ruthenium, Cp*Rh and Cp*Ir oximato and oxime complexes: Synthesis, structural, DFT and biological studies
The reaction of [(p-cymene)RuCl2]2 and [Cp*MCl2]2 (M = Rh/Ir) with chelating ligand 2-pyridylcyanoxime {pyC(CN)NOH} leads to the formation of neutral oximato complexes having the general formula [(arene)M{pyC(CN)NO}Cl] {arene = p-cymene, M = Ru, (1); Cp*, M = Rh (2);Cp*, M = Ir (3)}. Whereas the reaction of 2-pyridyl phenyloxime {pyC(Ph)NOH} and 2-thiazolyl methyloxime {tzC(Me)NOH} with precursor compounds afforded the cationic oxide complexes bearing formula [(arene)M{pyC(ph)NOH}Cl]+ and [(arene)M{tzC(Me)NOH}Cl]+{arene = p-cymene M = Ru, (4), (7); Cp*, M = Rh (5), (8); Cp*, M = Ir (6), (9)}. The cationic complexes were isolated as their hexafluorophosphate salts. All these complexes were fully characterized by analytical, spectroscopic and X-ray diffraction studies. The molecular structures of the complexes revealed typical piano stool geometry around the metal center within which the ligand acts as a NNʹ donor chelating ligand. The Chemo-sensitivity activities of the complexes evaluated against HT-29 (human colorectal cancer), and MIAPaCa-2 (human pancreatic cancer) cell line showed that the iridium-based complexes are much more potent than the ruthenium and rhodium analogues. Theoretical studies were carried out to have a deeper understanding about the charge distribution pattern and the various electronic transitions occurring in the complexes
Veno-venous extracorporeal membrane oxygenation in pregnancy: does foetal viability matter?
With the increasing use of extracorporeal membrane oxygenation for adults with acute hypoxic respiratory failure, the indications for its use have expanded. We wanted to share the results of a recent case from our institution, of a woman who experienced respiratory failure secondary to hyperemesis gravidarum (HG). HG is a rare complication of pregnancy (0.3% to 2.0% of pregnancies), resulting in uncontrolled or excessive nausea and vomiting with dehydration and weight loss, typically in the first to mid second trimester, and is a diagnosis of exclusion
Low-Temperature Specific Heat of an Extreme-Type-II Superconductor at High Magnetic Fields
We present a detailed study of the quasiparticle contribution to the
low-temperature specific heat of an extreme type-II superconductor at high
magnetic fields. Within a T-matrix approximation for the self-energies in the
mixed state of a homogeneous superconductor, the electronic specific heat is a
linear function of temperature with a linear- coefficient
being a nonlinear function of magnetic field . In the range of magnetic
fields H\agt (0.15-0.2)H_{c2} where our theory is applicable, the calculated
closely resembles the experimental data for the borocarbide
superconductor YNiBC.Comment: 7 pages, 2 figures, to appear in Physical Review
Analysis of three-nucleon forces effects in the system
Using modern nucleon-nucleon interactions in the description of the
nuclear systems the per datum results to be much bigger than one. In
particular it is not possible to reproduce the three- and four-nucleon binding
energies and the scattering length simultaneously. This is one
manifestation of the necessity of including a three-nucleon force in the
nuclear Hamiltonian. In this paper we perform an analysis of some, widely used,
three-nucleon force models. We analyze their capability to describe the
aforementioned quantities and, to improve their description, we propose
modifications in the parametrization of the models. The effects of these new
parametrization are studied in some polarization observables at low energies.Comment: 10 pages, to be published in Few-Body Systems. Presented at the
workshop on "Relativistic Description of Two- and Three-body Systems in
Nuclear Physics" ECT* Trento, 19 - 23 October 200
Collective dynamics of internal states in a Bose gas
Theory for the Rabi and internal Josephson effects in an interacting Bose gas
in the cold collision regime is presented. By using microscopic transport
equation for the density matrix the problem is mapped onto a problem of
precession of two coupled classical spins. In the absence of an external
excitation field our results agree with the theory for the density induced
frequency shifts in atomic clocks. In the presence of the external field, the
internal Josephson effect takes place in a condensed Bose gas as well as in a
non-condensed gas. The crossover from Rabi oscillations to the Josephson
oscillations as a function of interaction strength is studied in detail.Comment: 18 pages, 2 figure
Disorder Effects in Superconducting Multiple Loop Quantum Interferometers
A theoretical study is presented on a number N of resistively shunted
Josephson junctions connected in parallel as a disordered 1D array by
superconducting wiring in such a manner that there are N-1 individual SQUID
loops with arbitrary shape formed.Comment: 4 pages, 2 figure
Quality of online self-management resources for adults living with primary brain cancer, and their carers: a systematic environmental scan
Background: A primary brain cancer diagnosis is a distressing, life changing event. It adversely affects the quality of life for the person living with brain cancer and their families (‘carers’). Timely access to evidence-based information is critical to enabling people living with brain cancer, and their carers, to self-manage the devastating impacts of this disease.
Method: A systematic environmental scan of web-based resources. A depersonalised search for online English-language resources published from 2009 to December 2019 and designed for adults (> 25 years of age), living with primary brain cancer, was undertaken using the Google search engine. The online information was classified according to: 1) the step on the cancer care continuum; 2) self-management domains (PRISMS taxonomy); 3) basic information disclosure (Silberg criteria); 4) independent quality verification (HonCode); 5) reliability of disease and treatment information (DISCERN Sections 1 and 2); and readability (Flesch-Kincaid reading grade).
Results: A total of 119 online resources were identified, most originating in England (n = 49); Australia (n = 27); or the USA (n = 27). The majority of resources related to active treatment (n = 76), without addressing recurrence (n = 3), survivorship (n = 1) or palliative care needs (n = 13). Few online resources directly provided self-management advice for adults living with brain cancer or their carers. Just over a fifth (n = 26, 22%) were underpinned by verifiable evidence. Only one quarter of organisations producing resources were HonCode certified (n = 9, 24%). The median resource reliability as measured by Section 1, DISCERN tool, was 56%. A median of 8.8 years of education was required to understand these online resources.
Conclusions: More targeted online information is needed to provide people affected by brain cancer with practical self-management advice. Resources need to better address patient and carer needs related to: rehabilitation, managing behavioural changes, survivorship and living with uncertainty; recurrence; and transition to palliative care. Developing online resources that don’t require a high level of literacy and/or cognition are also required
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