Effect of temperature and salinity stress on growth and lipid composition of Shewanella gelidimarina

The maximum growth temperature, the optimal growth temperature, and the estimated normal physiological range for growth of Shewanella gelidimarina are functions of water activity (a(w)), which can be manipulated by changing the concentration of sodium chloride. The growth temperatures at the boundaries of the normal physiological range for growth were characterized by increased variability in fatty acid composition. Under hyper- and hypoosmotic stress conditions at an a(w) of 0.993 (1.0% [wt/vol] NaCl) and at an a(w) of 0.977 (4.0% [wt/vol] NaCl) the proportion of certain fatty acids (monounsaturated and branched-chain fatty acids) was highly regulated and was inversely related to the growth rate over the entire temperature range. The physical states of lipids extracted from samples grown at stressful a(w) values at the boundaries of the normal physiological range exhibited no abrupt gel-liquid phase transitions when the lipids were analyzed as liposomes. Lipid packing and adaptational fatty acid composition responses are clearly influenced by differences in the temperature-salinity regime, which are reflected in overall cell function characteristics, such as the growth rate and the normal physiological range for growth.Instituto de Investigaciones Bioquímicas de La Plat

Optical modulation in a resonant tunneling relaxation oscillator

We report high-speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band edge, small changes of the applied voltage give rise to large, high-speed electroabsorption modulation of the light. We have observed optical modulation at frequencies up to 14 GHz, associated with subharmonic injection locking of the RTD oscillation at the fundamental mode of the coplanar transmission line, as well as generation of 33 ps optical pulses due to relaxation oscillation

Optical modulation at around 1550 nm in an InGaAlAs optical waveguide containing an InGaAs/AlAs resonant tunneling diode

We report electroabsorption modulation of light at around 1550 nm in a unipolar InGaAlAs optical waveguide containing an InGaAs/AlAs double-barrier resonant tunneling diode ~RTD!. The RTD peak-to-valley transition increases the electric field across the waveguide, which shifts the core material absorption band edge to longer wavelengths via the Franz–Keldysh effect, thus changing the light-guiding characteristics of the waveguide. Low-frequency characterization of a device shows modulation up to 28 dB at 1565 nm. When dc biased close to the negative differential conductance region, the RTD optical waveguide behaves as an electroabsorption modulator integrated with a wide bandwidth electrical amplifier, offering a potential advantage over conventional pn modulators

A review of size and geometrical factors influencing resonant frequencies in metamaterials

Although metamaterials and so-called left-handed media have originated from theoretical considerations, it is only by their practical fabrication and the measurement of their properties that they have gained credibility and can fulfil the potential of their predicted properties. In this review we consider some of the more generally applicable fabrication methods and changes in geometry as they have progressed, exhibiting resonant frequencies ranging from radio waves to the visible optical region

Quantifying the cost savings and health impacts of improving colonoscopy quality: an economic evaluation

\ua9 Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.Objective: To estimate and quantify the cost implications and health impacts of improving the performance of English endoscopy services to the optimum quality as defined by postcolonoscopy colorectal cancer (PCCRC) rates. Design: A semi-Markov state-transition model was constructed, following the logical treatment pathway of individuals who could potentially undergo a diagnostic colonoscopy. The model consisted of three identical arms, each representing a high, middle or low-performing trust\u27s endoscopy service, defined by PCCRC rates. A cohort of 40-year-old individuals was simulated in each arm of the model. The model\u27s time horizon was when the cohort reached 90 years of age and the total costs and quality-adjusted life-years (QALYs) were calculated for all trusts. Scenario and sensitivity analyses were also conducted. Results: A 40-year-old individual gains 0.0006 QALYs and savings of \ua36.75 over the model lifetime by attending a high-performing trust compared with attending a middle-performing trust and gains 0.0012 QALYs and savings of \ua314.64 compared with attending a low-performing trust. For the population of England aged between 40 and 86, if all low and middle-performing trusts were improved to the level of a high-performing trust, QALY gains of 14 044 and cost savings of \ua3249 311 295 are possible. Higher quality trusts dominated lower quality trusts; any improvement in the PCCRC rate was cost-effective. Conclusion: Improving the quality of endoscopy services would lead to QALY gains among the population, in addition to cost savings to the healthcare provider. If all middle and low-performing trusts were improved to the level of a high-performing trust, our results estimate that the English National Health Service would save approximately \ua35 million per year

RNA Sequencing Demonstrates Ex Vivo Neocortical Transcriptomic Changes Induced by Epileptiform Activity in Male and Female Mice

\ua9 2024 Vaughan et al. Seizures are generally associated with epilepsy but may also be a symptom of many other neurological conditions. A hallmark of a seizure is the intensity of the local neuronal activation, which can drive large-scale gene transcription changes. Such changes in the transcriptional profile likely alter neuronal function, thereby contributing to the pathological process. Therefore, there is a strong clinical imperative to characterize how gene expression is changed by seizure activity. To this end, we developed a simplified ex vivo technique for studying sei-zure-induced transcriptional changes. We compared the RNA sequencing profile in mouse neocor-tical tissue with up to 3 h of epileptiform activity induced by 4-aminopyridine (4AP) relative to control brain slices not exposed to the drug. We identified over 100 genes with significantly altered expression after 4AP treatment, including multiple genes involved in MAPK, TNF, and neuroinflammatory signaling pathways, all of which have been linked to epilepsy previously. Notably, the patterns in male and female brain slices were almost identical. Various immediate early genes were among those showing the largest upregulation. The set of down-regulated genes included ones that might be expected either to increase or to decrease neuronal excitability. In summary, we found the seizure-induced transcriptional profile complex, but the changes aligned well with an analysis of published epilepsy-associated genes. We discuss how simple models may provide new angles for investigating seizure-induced transcriptional changes

Effect of temperature and salinity stress on growth and lipid composition of Shewanella gelidimarina

The maximum growth temperature, the optimal growth temperature, and the estimated normal physiological range for growth of Shewanella gelidimarina are functions of water activity (a(w)), which can be manipulated by changing the concentration of sodium chloride. The growth temperatures at the boundaries of the normal physiological range for growth were characterized by increased variability in fatty acid composition. Under hyper- and hypoosmotic stress conditions at an a(w) of 0.993 (1.0% [wt/vol] NaCl) and at an a(w) of 0.977 (4.0% [wt/vol] NaCl) the proportion of certain fatty acids (monounsaturated and branched-chain fatty acids) was highly regulated and was inversely related to the growth rate over the entire temperature range. The physical states of lipids extracted from samples grown at stressful a(w) values at the boundaries of the normal physiological range exhibited no abrupt gel-liquid phase transitions when the lipids were analyzed as liposomes. Lipid packing and adaptational fatty acid composition responses are clearly influenced by differences in the temperature-salinity regime, which are reflected in overall cell function characteristics, such as the growth rate and the normal physiological range for growth.Instituto de Investigaciones Bioquímicas de La Plat

Solar Concentrators

Solar technology offers great potential in terms of supplying the world's energy needs. However, its current contribution to the world is still limited. The main factor is related to high initial cost of building the system. This paper will provide an up-to-date review of solar concentrators and their benefits to make solar technology affordable. It will also analyse on some of the existing solar concentrators used in the solar technology for the past four decades. The design and performance of each concentrator will be explained and compared

Solar Concentrators

Solar technology offers great potential in terms of supplying the world's energy needs. However, its current contribution to the world is still limited. The main factor is related to high initial cost of building the system. This paper will provide an up-to-date review of solar concentrators and their benefits to make solar technology affordable. It will also analyse on some of the existing solar concentrators used in the solar technology for the past four decades. The design and performance of each concentrator will be explained and compared