Fault-Tolerant Strassen-Like Matrix Multiplication

In this study, we propose a simple method for fault-tolerant Strassen-like matrix multiplications. The proposed method is based on using two distinct Strassen-like algorithms instead of replicating a given one. We have realized that using two different algorithms, new check relations arise resulting in more local computations. These local computations are found using computer aided search. To improve performance, special parity (extra) sub-matrix multiplications (PSMMs) are generated (two of them) at the expense of increasing communication/computation cost of the system. Our preliminary results demonstrate that the proposed method outperforms a Strassen-like algorithm with two copies and secures a very close performance to three copy version using only 2 PSMMs, reducing the total number of compute nodes by around 24\% i.e., from 21 to 16.Comment: 6 pages, 2 figure

Quantum beat spectroscopy: stimulated emission probe of hyperfine quantum beats in the atomic Cs 8p 2P3/2^{2}P_{3/2} level

Measurements of hyperfine polarization quantum beats are used determine the magnetic dipole (A) and electric quadrupole (B) coupling constants in the excited atomic Cs 8p level. The experimental approach is a novel combination of pulsed optical pumping and time-delayed stimulated emission probing of the excited level. From the measured evolution of the atomic linear polarization degree as a function of probe delay time, we determine the hyperfine coupling constants A = 7.42(6) MHz and B = 0.14(29) MHz

A new stakeholder opinion-based rapid sustainability assessment method (RSAM) for existing residential buildings

In many developing countries, several strategies and programs have been established to support the green building initiative, but overall progress is too slow to keep up with the global advances. To accelerate progress in building sustainability as well as to aid the decision-making process of different parties involved, a tailored quantification method for the sustainability performance of buildings is needed. The study presents a Rapid Sustainability Assessment Method (RSAM) – a fast and easy-to-implement system developed using indicators and their respective weights obtained from stakeholders and an assessment approach based on residents’ responses. It was then applied to measure the sustainability performance of several residential buildings (from eras: before 1991, from 1991 to 1998, and after 1998) in the capital of Kazakhstan, Nur-Sultan (formerly Astana). Results differentiated well between the buildings of different era, revealing that even new buildings certified via international green building rating systems do not entirely satisfy the vision of sustainability of the capital’s residents. Although the residents’ opinion-based method was developed for existing residential buildings, it is flexible enough to accommodate future changes e.g. including data obtained from other stakeholders (e.g. building management) and assessing non-residential buildings. RSAM is further applicable to residential buildings constructed after 1950s in other similar regions including post-Soviet and Eastern Bloc countries

Measuring local RF heating in MRI: Simulating perfusion in a perfusionless phantom

Purpose: To overcome conflicting methods of local RF heating measurements by proposing a simple technique for predicting in vivo temperature rise by using a gel phantom experiment. Materials and Methods: In vivo temperature measurements are difficult to conduct reproducibly; fluid phantoms introduce convection, and gel phantom lacks perfusion. In the proposed method the local temperature rise is measured in a gel phantom at a timepoint that the phantom temperature would be equal to the perfused body steady-state temperature value. The idea comes from the fact that the steady-state temperature rise in a perfused body is smaller than the steady-state temperature increase in a perfusionless phantom. Therefore, when measuring the temperature on a phantom there will be the timepoint that corresponds to the perfusion time constant of the body part. Results: The proposed method was tested with several phantom and in vivo experiments. Instead, an overall average of 30.8% error can be given as the amount of underestimation with the proposed method. This error is within the variability of in vivo experiments (45%). Conclusion: With the aid of this reliable temperature rise prediction the amount of power delivered by the scanner can be controlled, enabling safe MRI examinations of patients with implants. © 2007 Wiley-Liss, Inc

Melatonin Delays Brain Aging by Decreasing the Nitric Oxide Level

Aging is believed to be a first-order risk factor for most neurodegenerative disorders. The neuronal cell loss that occurs with aging has been partly attributed to increased production of nitric oxide and high caspase activity. Melatonin (MLT) might have a role in the regulation of nitric oxide in the brain. We investigated the effects of MLT on the nitrite/nitrate levels and caspase-3 enzyme activity in the frontal cortex, temporal cortex, and hippocampus of young and aged rats. There was no significant difference between the nitrite levels in the frontal cortex and hippocampus of young and aged animals. In the temporal cortex of aged rats, the nitrite level, however, was significantly higher (P < 0.001). In the aged group, MLT significantly decreased these levels in the brain regions. Caspase-3 enzyme activity in the temporal and frontal cortices was significantly higher in aged rats when compared to the control group (P < 0.05). Melatonin did not cause significant changes in caspase-3 activity in any brain region of both young and aged rats. Thus, brain regions demonstrate different caspase-3 enzyme activities and nitrite levels in the aging process. Exogenous MLT administration might delay brain aging (by moderation of death of neurons and glia) via decreasing the nitrite level.В аспекті розвитку нейродегенеративних розладів старіння розглядається як фактор ризику першого порядку. Втрату нервових клітин, яка відбувається з віком, пов’язували, в усякому разі частково, зі збільшенням продукції оксиду азоту та високій активності каспаз. Мелатонін (МТ) може відігравати певну роль у регуляції рівня оксиду азоту в мозку. Ми досліджували впливи МТ на рівні нітритів/нитратів та ензиматичну активність каспази-3 у фронтальній і темпоральній корі та гіпокампі молодих і старих щурів. Істотних відмінностей між рівнями нітритів у фронтальній корі та гіпокампі молодих і старих тварин виявлено не було, проте цей рівень в темпоральній корі старих тварин був істотно вищим (P < 0.001). У групі старих щурів МТ істотно знижував рівні нітритів в структурах мозку. Активність каспази-3 у фронтальних і темпоральних зонах кори старих щурів була достовірно вище, ніж у контрольних тварин (P < 0.05). Мелатонін не викликав істотних змін активності каспази-3 у всіх досліджених структурах мозку як молодих, так і старих щурів. Отже, рівні активності каспази-3 та концентрації нітритів в різних структурах мозку в перебігу процесу старіння демонструють певну специфічність. Вплив екзогенного МТ, мабуть, затримує старіння мозку (зменшуючи інтенсивність загибелі нейронів і глії) за рахунок зниження рівнів нітрит

A simple analytical expression for the gradient induced potential on active implants during MRI

During magnetic resonance imaging, there is an interaction between the time-varying magnetic fields and the active implantable medical devices (AIMD). In this study, in order to express the nature of this interaction, simplified analytical expressions for the electric fields induced by time-varying magnetic fields are derived inside a homogeneous cylindrical volume. With these analytical expressions, the gradient induced potential on the electrodes of the AIMD can be approximately calculated if the position of the lead inside the body is known. By utilizing the fact that gradient coils produce linear magnetic field in a volume of interest, the simplified closed form electric field expressions are defined. Using these simplified expressions, the induced potential on an implant electrode has been computed approximately for various lead positions on a cylindrical phantom and verified by comparing with the measured potentials for these sample conditions. In addition, the validity of the method was tested with isolated frog leg stimulation experiments. As a result, these simplified expressions may help in assessing the gradient-induced stimulation risk to the patients with implants. © 1964-2012 IEEE

Past Achievements and Future Challenges in 3D Photonic Metamaterials

Photonic metamaterials are man-made structures composed of tailored micro- or nanostructured metallo-dielectric sub-wavelength building blocks that are densely packed into an effective material. This deceptively simple, yet powerful, truly revolutionary concept allows for achieving novel, unusual, and sometimes even unheard-of optical properties, such as magnetism at optical frequencies, negative refractive indices, large positive refractive indices, zero reflection via impedance matching, perfect absorption, giant circular dichroism, or enhanced nonlinear optical properties. Possible applications of metamaterials comprise ultrahigh-resolution imaging systems, compact polarization optics, and cloaking devices. This review describes the experimental progress recently made fabricating three-dimensional metamaterial structures and discusses some remaining future challenges

The Thermal Behaviour of Three Different Auger Pressure Grouted Piles Used as Heat Exchangers

Three auger pressure grouted (APG) test piles were constructed at a site in Richmond, Texas. The piles were each equipped with two U-loops of heat transfer pipes so that they could function as pile heat exchangers. The piles were of two different diameters and used two different grouts, a standard APG grout and a thermally enhanced grout. Thermal response tests, where fluid heated at a constant rate is circulated through the pipe loops, were carried out on the three piles, utilising either single or double loops. The resulting test data can be used to determine the surrounding soil thermal conductivity and the pile thermal resistance, both essential design parameters for ground source heat pump systems using pile heat exchangers. This paper uses parameter estimation techniques to fit empirical temperature response curves to the thermal response test data and compares the results with standard line source interpretation techniques. As expected, the thermal response tests with double loops result in smaller thermal resistances than the same pile when the test was run with a single loop. Back analysis of the pile thermal resistance also allows calculation of the grout thermal properties. The thermally enhanced grout is shown to have inferior thermal properties than the standard APG grout. Together these analyses demonstrate the importance of pile size, grout thermal properties and pipe positions in controlling the thermal behaviour of heat exchanger piles