Delayed effects of chronic low-dose high linear energy transfer (LET) radiation on mice in vivo

In the present work, the delayed effects of chronic high linear energy transfer (LET) radiation in polychromatic erythrocytes (PCEs) of mice bone marrow were investigated in vivo. Irradiation of the two-month-old SHK white mongrel random-bred male mice was performed in the radiation field behind the concrete shield of the accelerator of 70 GeV protons to accumulate doses of 0.005-0.16 Gy. The dependence of the biological response on dose, adaptive response (AR) and genomic instability (GI) in F(1) and F(2) generations from males irradiated with doses of 0.005 and 0.16 Gy and from males exposed to combined action of immunomodulator-bendazol hydrochloride (BH) and of 0.16 Gy irradiation, were examined using the micronucleus formation test. The data demonstrated that irradiation of mice with these doses lead to an increase in the level of cytogenetic damage and induces no AR. With analysis of the bone marrow radiosensitivity to 1.5 Gy of X rays and the capacity to AR it was found that the chronic high-LET irradiation of parents induced the GI at least two generations. The combined exposure to BH and the dose of 0.16 Gy induces no AR in F(0) generation but induces AR in F(1) and F(2) offspring.     

Passive spectrometry of linear energy transfer: development and use

A linear energy transfer (LET) spectrometer based on the evaluation of particle track parameters in a chemically etched polyallyldiglycolcarbonate (PADC) track detector has been developed at our laboratory. It permits us to determine LET spectra between 10 and 700 keV microm(-1) in tissues. The LET spectra obtained permit us to calculate total dose and dose equivalent corresponding to particles with etchable tracks also. We have recently been able to verify the calibration curves used by using C, Mg, Ne, Si and Fe ion beams with different energies. The calibration curves obtained are presented and compared with those originally used, and a good correlation is found. The LET spectrometer with new calibration was used to analyse the radiation quality of the radiotherapy proton beam at the Joint Institute for Nuclear Research (JINR). The radiation quality was studied along the proton's range, particular attention being devoted to the region of the Bragg peak. It was found that the biologically weighted effective dose (BWE) reaches a value of about 1.25 at the Bragg peak region. At the beam entrance this value increases to about 1.02 due to secondary particles created through primary proton nuclear reactions in tissues.     

Label-acquired magnetorotation as a signal transduction method for protein detection: aptamer-based detection of thrombin

This paper presents a new signal transduction method, called label-acquired magnetorotation (LAM), for the measurement of the concentration of proteins in solution. We demonstrate the use of LAM to detect the protein thrombin using aptamers, with a limit of detection of 300 pM. LAM is modeled after a sandwich assay, with a 10 μm nonmagnetic "mother" sphere as the capture component and with 1 μm magnetic "daughter" beads as the labels. The protein-mediated attachment of daughter beads to the mother sphere forms a rotating sandwich complex. In a rotating magnetic field, the rotational frequency of a sandwich complex scales with the number of attached magnetic beads, which scales with the concentration of the protein present in solution. This paper represents the first instance of the detection of a protein using LAM.     

Effect of stochasticity on targeted energy transfer from a linear medium to a strongly nonlinear attachment

In this work the problem of targeted energy transfer (TET) from a linear medium to a nonlinear attachment is studied in the presence of stochasticity. Using a Green’s function formulation, complexification-averaging technique and diffusion approximation we derive a complex, nonlinear, Ito stochastic differential equation that governs the slow dynamics of the system. Through the numerical solution of the corresponding Fokker-Planck-Kolmogorov (FPK) equation we study the optimal regime of TET and its robustness to stochasticity for the case of nonlinear interactions of the nonlinear attachment with a single mode of the linear system. The probabilistic analysis reveals that in the presence of stochasticity the optimal TET regime, predicted in the deterministic theory, is not only preserved but also is enhanced due to the interaction of nonlinearity and stochasticity.     

No evidence for a low linear energy transfer adaptive response in irradiated RKO cells

It has become increasingly evident from reports in the literature that there are many confounding factors capable of modulating radiation-induced non-targeted responses, such as the bystander effect and the adaptive response. In this paper, we examine recent data which suggest that the observation of non-targeted responses may not be universally observable for differing radiation qualities. We have conducted a study of the adaptive response following low-linear energy transfer exposures for human colon carcinoma cells and failed to observe adaption for the endpoints of clonogenic survival or micronucleus formation.     

Simple method for minimax linear approximation of the transfer function of a measurement device

Translated from Izmeritel'naya Tekhnika, No. 3, pp. 19–21, March, 1992.     

Lineal energy as a function of site size for HZE radiation

Monte Carlo calculations have been used to estimate the frequency and magnitude of energy deposition events produced by delta rays originating with high atomic number, high-energy, primary particles. The results show that the spectrum of delta rays incident on small targets is relatively insensitive to primary particle velocity or distance to the primary track. They suggest that measurements of energy deposition in different size sites can be used to characterise the velocity of the incident particle.     

Modulation transfer function evaluation of linear solid-state x-ray-sensitive detectors using edge techniques

The exact determination of the modulation transfer function (MTF) of a physical system is a persistent problem. We present a practical method of measuring numerically the MTF of linear solid-state x-ray-sensitive detectors. The method is based on the use of edge techniques and allows us to obtain the MTF of a linear detector from its edge-spread function (ESF). ESF measurement techniques are discussed in detail, and calculation of the corresponding MTF's are shown.     

Optical transfer function design by use of a phase-only coherent transfer function

The design of a desired optical transfer function (OTF) is a common optical problem that has many possible applications. A well-known application for the OTF design is beam shaping for incoherent illumination. However, other applications, such as optical signal processing, can also be addressed with these systems. We derive a mathematical expression for an optimal phase-only filter that, when attached to an imaging lens, provides an optimal approximation in the sense of the minimal mean square error to the desired OTF function. Because of the fact that a phase-only filter is used, high efficiency is achieved.     

Photorefractive beam-steering system that uses energy transfer in a BaTiO(3) crystal for a fiber-array interconnect

A beam-control system to write gratings on a holographic plane is studied. The arrangement is designed to interconnect two 1024 monomode fiber arrays. The beam-control system is composed of two subsystems: a beam steerer, which deflects one incident beam toward 1024 positions, and a collimating system, which adapts the shape of the deflected beam to the holographic plane. The collimating system was studied only after the beam steerer had been fully built and tested. It is based on the photorefractive amplification of a beamlet selected by a shutter array. The deflection efficiency is enhanced by a factor 1500 with the photorefractive crystal, and the signal-to-noise ratio is larger than 5500. The influence of the optical aberrations on the coupling losses of the infrared beams in the monomode fibers are evaluated.     

A microprocessor-based on-line optical transfer function (OTF)measurement system

The development of a microprocessor-based optoelectronic system for the measurement of the optical transfer function (OTF) is considered. The method used is based on the edge image analysis. The edge intensity distribution data are stored in the microprocessor, and the computation of OTF from these data is made using the process software. The present technique avoids the differentiation and makes a clever use of edge data as such. The practical difficulty of instrumentation of the FFT technique for the required Fourier transformation has been avoided by the use of Walsh block expansion of the function to be Fourier transformed. The details of the programming as well as some experimental results using standard lens are also reported     

Distortion of superfluid3He-B energy gap as a function of magnetic field

Ultrasound measurements of the pair-breaking edge of superfluid³He-B have provided a quantitative knowledge of the energy gap distortion in a magnetic field. The gap distortions obtained at very low temperatures for the three sound frequencies 168.3, 137.6 and 107 MHz are plotted against magnetic field. Results are consistent with theoretical estimates.     

On a signal processing algorithms based class of linear codes

In this work, the correspondence between linear (n,k,d) codes and aperiodic convolution algorithms for computing a system ofk bilinear forms over GF(p^m) is explored. A number of properties are established for the linear codes that can be obtained from a computational procedure of this type. A particular bilinear form is considered and a class of linear codes over GF(2^m) is derived with varyingk andd parameters. The code lengthn is equal to the multiplicative complexity of the computation of an aperiodic convolution and an efficient computation thereof leads to the shortest codes possible using this approach, many of which are optimal or near-optimal. A new decoding procedure for this class of linear codes is presented which exploits the block structure of the generator matrix of the codes. Several interesting observations are made on the nature of the codes obtained as a result of such computations. Such a computation of bilinear forms can be generalized to include other bilinear forms and the related classes of codes.     

Spectra of linear energy transfer and other dosimetry characteristics as measured in C290 MeV/n MONO and SOBP ion beams at HIMAC-BIO (NIRS, Japan) with different detectors

Active mobile dosimetry unit (Liulin), passive plastic nuclear track detectors (PNTD) and thermoluminescent detectors (TLD) were exposed in a C290 MeV/n beam at HIMAC-BIO (NIRS, Japan). Two different types of beam configuration were used--monoenergetic beam (MONO) and spread-out Bragg peak (SOBP); the detectors were placed at several depths from the entrance up to the depths behind the Bragg peak. Relative response of TLDs in beams has been studied as a function of the depth, and it was re-proved that it can depend on the linear energy transfer (LET). Liulin measures energy deposition in Si; the spectra of energy deposited in Si can be transformed to the spectra of lineal energy or LET. PNTDs are able to determine the LET of registered particles directly. The limitation of both methods is in the range in which they can determine the LET-Liulin is able to measure perpendicularly incident charged particles up to ～35 keV/μm (in water), PNTD can measure from ～7 to 400 keV/μm, independently of the registration angle. The results from both methods are compared and combined for both beams' configuration, and a good agreement is observed.     

On-chip transduction of nucleic acid hybridization using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer

The glass surface of a glass-polydimethylsiloxane (PDMS) microfluidic channel was modified to develop a solid-phase assay for quantitative determination of nucleic acids. Electroosmotic flow (EOF) within channels was used to deliver and immobilize semiconductor quantum dots (QDs), and electrophoresis was used to decorate the QDs with oligonucleotide probe sequences. These processes took only minutes to complete. The QDs served as energy donors in fluorescence resonance energy transfer (FRET) for transduction of nucleic acid hybridization. Electrokinetic injection of fluorescent dye (Cy3) labeled oligonucleotide target into a microfluidic channel and subsequent hybridization (within minutes) provided the proximity for FRET, with emission from Cy3 being the analytical signal. The quantification of target concentration was achieved by measurement of the spatial length of coverage by target along a channel. Detection of femtomole quantities of target was possible with a dynamic range spanning an order of magnitude. The assay provided excellent resistance to nonspecific interactions of DNA. Further selectivity of the assay was achieved using 20% formamide, which allowed discrimination between a fully complementary target and a 3 base pair mismatch target at a contrast ratio of 4:1.     

Nonradiative energy transfer from titanium (III) ions to erbium (III) ions in aluminosilicophosphate glass

A luminophor based on aluminosilicophosphate glass doped with erbium (III) and titanium (III) has been synthesized. It is shown that the erbium luminescence in this glass is efficiently sensitized by the titanium ions via the ⁴I_13/2→⁴I_15/2 channel (λ=1.538 μm). It is determined that the transport is by a dipole-dipole mechanism. The critical transport concentration is 0.032 M, and the critical transport distance is 1.95 nm. Pis’ma Zh. Tekh. Fiz. 23, 7–11 (November 12, 1997)     

Stability of a linear algorithm for signal observation in a gravitational-wave experiment

The sensitivity is discussed for a linear signal-detection algorithm resulting from change in the a priori information is a gravitational wave experiment.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 3–4, September, 1995.