Optical properties of suspensions of gold half-shells

Suspensions of mesoscale gold half-shells of controlled size were produced by microsphere-templated vapour deposition and their optical properties were studied. The transmission spectra of the particles exhibited an extinction peak that could be tuned from 530 to over 2000 nm by variation of the diameter of the template used. In this respect the optical properties of these reduced-symmetry particles are similar to those of full nanoshells, however they may be more convenient to prepare. © 2007 Elsevier B.V. All rights reserved

Tunable infrared absorption by metal nanoparticles: The case for gold rods and shells

Nanoparticles of elements such as Au, Al or Ag have optical extinction cross-section that considerably surpass their geometric cross-sections at certain wavelengths of light. While the absorption and scattering maxima for nanospheres of these elements are relatively insensitive to particle diameter, the surface plasmon resonance of Au nanoshells and nanorods can be readily tuned from the visible into the infrared by changing the shape of the particle. Here we compare nanoshells and nanorods in terms of their ease of synthesis, their optical properties, and their longer term technological prospects as tunable "plasmonic absorbers". While both particle types are now routinely prepared by wet chemistry, we submit that it is more convenient to prepare rods. Furthermore, the plasmon resonance and peak absorption efficiency in nanorods may be readily tuned into the infrared by an increase of their aspect ratio, whereas in nanoshells such tuning may require a decrease in shell thickness to problematic dimensions

Laser-induced assembly of gold nanoparticles into colloidal crystals

Micron-sized colloidal crystals comprised of gold nanospheres have been synthesized directly from a gold nanoparticle/methyl methacrylate colloid by application of a 514 nm laser at 500 mW. An array of colloidal crystals can be created by translation of the glass substrate under the laser beam, after 2 min of irradiation at each site. We demonstrate through a series of control experiments and calculations that plasmon-induced, localized heating of the gold nanoparticles contributes to the mechanism responsible for the formation of these colloidal crystals. © IOP Publishing Ltd

Mie and bragg plasmons in subwavelength silver semi-shells

2D arrays of silver semi-shells of 100 and 200 nm diameter display complex reflection and transmission spectra in the visible and near-IR. Here these spectral features are deconstructed and it is demonstrated that they result from the coupling of incident light into a delocalized Bragg plasmon, and the latter's induction of localized Mie plasmons in the arrays. These phenomena permit the excitation of transverse dipolar plasmon resonances in the semi-shells despite an ostensibly unfavorable orientation with respect to normally incident light. The resulting spectral feature in the mid-visible is strong and tunable. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA

Optimisation of absorption efficiency for varying dielectric spherical nanoparticles

In this paper we compare the optical absorption for nanospheres made from a range of transition and alkali metals from Li (A=3) to Au (A=79). Numerical solutions to Mie theory were used to calculate the absorption efficiency, Q abs, for nanospheres varying in radii between 5 nm and 100 nm in vacuum. We show that, although gold is the most commonly used nanoparticle material, its absorption efficiency at the plasmon resonance is not as strong as materials such as the alkali metals. Of all the materials tried, potassium spheres with a radius of 21 nm have an optimum absorption efficiency of 14.7. In addition we also show that, unlike gold, the wavelength of the plasmon peak in other materials is sensitive to the sphere radius. In potassium the peak position shifts by 100 nm for spheres ranging from 5 nm to 65 nm, the shift is less than 10 nm for gold spheres. © 2006 IEEE

"L'art poétique à l'usage du Petit Séminaire de Québec"

Y-a-t-il un « art poétique » surréaliste ? Si l'on en croit André Breton, non : lui se situe résolument du côté du « Manifeste », où l'art poétique se voit dénié sur ses deux versants - celui de l'artefact (techniques rhétoriques) et celui du poétique, engagé dans une « littérature » marquée ici du sceau de l'infamie. Le rationalisme éclate sous la pression d'une « raison élargie ». Simultanément, l'esprit du manifeste fait triompher les voies du désir : le « il y aura une fois » de « l'imagination ». D'où une téléologie de l'art, orienté vers sa « prophétie », et une épistémologie de sa réception, fondée sur l'éros. Ce qui suppose de ne pas glisser aux « techniques » qui mènent aux poncifs : d'où la Terreur.Is there a surrealist "poetic art" ? If we are to believe André Breton, the answer is No ; Breton for his part resolutely adheres to the "Manifesto". The possibility of a poetic art is denied both as art (rhetorical technique) and as poetry (a literary project here under the seal of infamy. The rationale of setting poetics in order collapses under the constraint of a "broader reason". At the same time, the spirit of the "Manifesto" marks the triumph of the ways of désire: the imperative "let there be" of the imagination. Hence there is a teleology of Art founded on "prophecy", and an epistemology of its réception based on Eros.The besetting danger is that "technique" (and consequently cliché) will predominate : hence the Terror

Hospital case volume and outcomes for proximal femoral fractures in the USA: an observational study

Objective: To explore whether older adults with isolated hip fractures benefit from treatment in high-volume hospitals. Design: Population-based observational study. Setting: All acute hospitals in California, USA. Participants: All individuals aged >65 that underwent an operation for an isolated hip fracture in California between 2007 and 2011. Patients transferred between hospitals were excluded. Primary and secondary outcomes: Quality indicators (time to surgery) and patient outcomes (length of stay, in-hospital mortality, unplanned 30-day re-admission, and selected complications). Results: 91,401 individuals satisfied the inclusion criteria. Time to operation and length of stay were significantly prolonged in low volume hospitals, by 1.96 (95% CI 1.20-2.73) and 0.70 (0.38-1.03) days respectively. However, there were no differences in clinical outcomes, including in-hospital mortality, 30-day re-admission, and rates of pneumonia, pressure ulcers, and venous thromboembolism. Conclusion: These data suggest that there is no patient safety imperative to limit hip fracture care to high-volume hospitals

Difficulties faced by older Rohingya (forcibly displaced Myanmar nationals) adults in accessing medical services amid the COVID-19 pandemic in Bangladesh

Background COVID-19 has seriously disrupted health services in many countries including Bangladesh. This research aimed to explore whether Rohingya (forcefully displaced Myanmar nationals) older adults in Bangladesh faced difficulties accessing medicines and routine medical care services amid this pandemic. Methods This cross-sectional study was conducted among 416 Rohingya older adults aged 60 years and above residing in Rohingya refugee camps situated in the Cox's Bazar district of Bangladesh and was conducted in October 2020. A purposive sampling technique was followed, and participants' perceived difficulties in accessing medicines and routine medical care were noted through face-to-face interviews. Binary logistic regression models determined the association between outcome and explanatory variables. Results Overall, one-third of the participants reported difficulties in accessing medicines and routine medical care. Significant factors associated with facing difficulties accessing medicine included feelings of loneliness (adjusted OR (AOR) 3.54, 95% CI 1.93 to 6.48), perceptions that older adults were at the highest risk of COVID-19 (AOR 3.35, 95% CI 1.61 to 6.97) and required additional care during COVID-19 (AOR 6.89, 95% CI 3.62 to 13.13). Also, the notable factors associated with difficulties in receiving routine medical care included living more than 30 min walking distance from the health centre (AOR 3.57, 95% CI 1.95 to 6.56), feelings of loneliness (AOR 2.20, 95% CI 1.25 to 3.87), perception that older adults were at the highest risk of COVID-19 (AOR 2.85, 95% CI 1.36 to 5.99) and perception that they required additional care during the pandemic (AOR 4.55, 95% CI 2.48 to 8.35). Conclusion Many Rohingya older adults faced difficulties in accessing medicines and routine medical care during this pandemic. This call for policy-makers and relevant stakeholders to re-assess emergency preparedness plans including strategies to provide continuing care

A rare case of term viable secondary abdominal pregnancy following rupture of a rudimentary horn: a case report

<p>Abstract</p> <p>Introduction</p> <p>Abdominal pregnancy is a rare event, but one that represents a grave risk to the health of the pregnant woman. An abdominal pregnancy is defined as an ectopic pregnancy that implants in the peritoneal cavity. Early abdominal pregnancy is self-limited by hemorrhage from trophoblastic invasion with complete abortion of the gestational sac that leaves a discrete crater. Advanced abdominal pregnancy is a rare event, with high fetal and maternal morbidity and mortality.</p> <p>Case presentation</p> <p>This is a case report of a 22-year-old primigravida with an abdominal pregnancy from a ruptured rudimentary horn. She was diagnosed as a case of term pregnancy with placenta previa with a transverse fetal lie and cervical fibroid and was prepared for an elective cesarean section. Intra-operatively, a live term female baby was extracted from the peritoneal cavity and it turned out to be an abdominal pregnancy from a ruptured rudimentary horn of a unicornuate uterus, which is a very rare condition. Mother and baby were in good condition after such a catastrophic event.</p> <p>Conclusion</p> <p>This case illustrates a rare obstetric condition which can be a severe catastrophic condition leading to maternal mortality and morbidity. It is imperative for every obstetrician to have in mind the possibility of abdominal pregnancy, although rare, especially in pregnant patients with persistent abdominal pain and painful fetal movements.</p

Distributions of charged massive scalars and fermions from evaporating higher-dimensional black holes

A detailed numerical analysis is performed to obtain the Hawking spectrum for charged, massive brane scalars and fermions on the approximate background of a brane charged rotating higher-dimensional black hole constructed in arXiv:0907.5107. We formulate the problem in terms of a "spinor-like" first order system of differential wave equations not only for fermions, but for scalars as well and integrate it numerically. Flux spectra are presented for non-zero mass, charge and rotation, confirming and extending previous results based on analytic approximations. In particular we describe an inverted charge splitting at low energies, which is not present in four or five dimensions and increases with the number of extra dimensions. This provides another signature of the evaporation of higher-dimensional black holes in TeV scale gravity scenarios.Comment: 19 pages, 6 figures, minor typos corrected, 1 page added with a discussion on higher spins, added reference