SARAS CD/EoR Radiometer: Design and Performance of the Digital Correlation Spectrometer

In the currently accepted model for cosmic baryon evolution, Cosmic Dawn (CD) and the Epoch of Reionization (EoR) are significant times when first light from the first luminous objects emerged, transformed and subsequently ionized the primordial gas. The 21[Formula: see text]cm (1420[Formula: see text]MHz) hyperfine transition of neutral hydrogen, redshifted from these cosmic times to a frequency range of 40[Formula: see text]MHz to 200[Formula: see text]MHz, has been recognized as an important probe of the physics of CD/EoR. The global 21[Formula: see text]cm signal is predicted to be a spectral distortion of a few 10’s to a few 100’s of mK, which is expected to be present in the cosmic radio background as a trace additive component. Shaped Antenna measurement of the background RAdio Spectrum (SARAS) is a spectral radiometer purpose designed to detect the weak 21[Formula: see text]cm signal from CD/EoR. An important subsystem of the radiometer, the digital correlation spectrometer, is developed around a high-speed digital signal processing platform called pSPEC. pSPEC is built around two quad 10-bit analog-to-digital converters (EV10AQ190) and a Virtex 6 (XC6VLX240T) field programmable gate array, with provision for multiple Gigabit Ethernet and 4.5[Formula: see text]Gbps fiber-optic interfaces. Here, we describe the system design of the digital spectrometer, the pSPEC board, and the adaptation of pSPEC to implement a high spectral resolution (61[Formula: see text]kHz), high dynamic range ([Formula: see text]:1) correlation spectrometer covering the entire CD/EoR band. As the SARAS radiometer is required to be deployed in remote locations where terrestrial radio frequency interference (RFI) is a minimum, the spectrometer is designed to be compact, portable and operating off internal batteries. The paper includes an evaluation of the spectrometer’s susceptibility to RFI and capability to detect signals from CD/EoR.

On Basic Requirements to Main Elements of Laser Correlation Spectrometer

Introduction. Laser correlation spectroscopy is a promising method that allows one to analyze sizes of nanoparticles and to evaluate their shape and dynamics of aggregation in liquids. A limited usage of laser correlation spectroscopy is currently caused by insufficient accuracy of existing instruments and data processing algorithms. The paper described the development of laser correlation spectroscopic hardware complex designed for nanoparticles size determination in liquids. The basic requirements for the elements of the device and the approaches used to calculate the signal-to-noise ratio were discussed. The achieved parameters of the laser correlation spectrometer were presented.Aim. To develop the hardware for nanoparticles size determination in liquids and to optimize the parameters of hardware elements to increase signal-to-noise ratio.Materials and methods. Theory of dynamic light scattering to describe scattering of laser radiation in liquids was applied. Fundamental requirements for the elements of the laser correlation spectrometer were described.Results. An original scheme of the laser correlation spectrometer was developed, the basic requirements for the general scheme elements were described. Equations for calculating signal-to-noise ratio were given.Conclusion. The analysis of the main parameters of the elements of the laser correlation spectroscopic scheme were carried out. It helps one to evaluate the expected signal-to-noise ratio in laser correlation spectrometers.

Assessment of metabolic changes in patients with heterogeneous metal orthopedic structures after dental-maxillary prosthetics

Совершенствование стоматологических технологий требует переоценки необходимости применения старых материалов для лечения и протезирования. При использовании разнородных металлических ортопедических конструкций в зубочелюстном протезировании развиваются местные реакции на металлы и возникают дерматиты, связанные с микротоками. Цель. Оценить характер и выраженность метаболических сдвигов в ротовой полости и их связь с используемыми для протезирования материалами. Методика. В исследовании приняли участие 133 пациента старше 60 лет, которые условно были разделены на 4 группы в зависимости от наличия или отсутствия металлических/пластиковых конструкций. Были получены рото-глоточные смывы, субфракционный состав которых исследовали на приборе «Лазерный корреляционный спектрометр ЛКС-03» (Интокс, РФ). Результаты. Протезирование с использованием одного металла приводит к возрастанию частоты встречаемости интоксикационноподобных сдвигов, а двух - аллерго- и дистрофическиподобных, чего в случае применения пластмасс не наблюдали. Improving dental technology requires reassessment of the use of old materials for treatment and prosthetics. Heterogeneous metal orthopedic structures in tooth-jaw prosthetics may induce local reactions to metals and dermatitis associated with microcurrents. Aim. To evaluate the nature and severity of metabolic changes in the oral cavity and their relationship with the materials used for prosthetics. Methods. The study involved 133 patients older than 60 who were conventionally divided into 4 groups based on the presence or absence of metal / plastic structures. Subfractional composition of oropharyngeal washouts was studied using an LCS-03 laser correlation spectrometer (Intox, Russia). Results. Prosthetics with a single metal increases the incidence of intoxication-like changes whereas using two metals increases allergic and dystrophic-like disorders, which was not observed in using plastics.

A fluorescence correlation spectrometer for measurements in cuvettes

ABSTRACTWe have developed a fluorescence correlation spectroscopy (FCS) setup for performing single molecule measurements on samples inside regular cuvettes. We built this by using an Extra Long Working Distance (ELWD), 0.7 NA, air objective with working distance > 1.8 mm. We have achieved counts per molecule > 44 kHz, diffusion time < 64 μs for rhodamine B in aqueous buffer and a confocal volume < 2 fl. The cuvette-FCS can be used for measurements over a wide range of temperature that is beyond the range permitted in the microscope-based FCS. Finally, we demonstrate that cuvette-FCS can be coupled to automatic titrators to study urea dependent unfolding of proteins with unprecedented accuracy. The ease of use and compatibility with various accessories will enable applications of cuvette-FCS in the experiments that are regularly performed in fluorimeters but are generally avoided in microscope-based FCS.