The Influence of Physical Characteristics of Accelerated Heavy Ions on the Formation and Repair of DNA Double-Strand Breaks

The kinetics of formation and elimination of γH2AX/53ВР1 foci induced by accelerated ¹¹B, ²⁰Ne, and ¹⁵N ions with different physical characteristics in human skin fibroblasts have been investigated. The results of the elimination kinetics for radiation-induced γH2AX/53BP1 foci (RIF) reveal that a decrease in the energy and an increase of the linear energy transfer (LET) of the particles reduce the efficiency of doublestrand break (DSB) repair. An investigation into the structure of RIF induced by accelerated ²⁰Ne and ¹¹B ions with various physical parameters shows significant differences in the nature of the RIF that is formed. It is found that ²⁰Ne ions with a high density of δ rays in tracks (Z*²/β² = 1454) induce larger clustered γH2AX/53BP1 foci with a more complex structure than ¹¹B ions with a lower density of δ rays in tracks (Z*²/β² = 494), which indicates the formation of more severe complex damage to genetic structures, first and foremost, DNA DSBs.     

Clustered DNA Double-Strand Breaks and Neuroradiobiological Effects of Accelerated Charged Particles

The irradiation of brain structures with accelerated heavy charged particles during interplanetary flights or brain tumor therapy raises a number of questions regarding possible neurophysiological disorders in the central nervous system (CNS). Hardly repairable clustered DNA double-strand breaks apparently can have significant influence on the specifics of the development of radiation syndromes in the CNS after heavy charged particle exposure. The mechanisms of these disorders still remain unclear. Taking this into account, we have used immune cyto- and histochemistry techniques to study regularities of the formation of radiationinduced foci in human cell DNA in vitro and in rodent brain neurons in vivo after exposure to charged particles of different energies. It has been found that heavy charged particles induce clustered DNA damage in the genome of proliferating (human fibroblasts) and non-proliferating (Purkinje neurons) cells. We have suggested that changes in genetic structures can affect the conformation of the key proteins participating in neurophysiological processes and violate the normal functioning of the synaptic receptors. As an example, we have considered the action of double point mutations in the gene sequence encoding the proteins of the glutamate receptor NMDA. Using computer molecular dynamics techniques, we have revealed a twofold change in the conductance of the receptor’s ion channel, which incorporates mutant forms of the protein subunits NR2.     

Mathematical Modeling of Canopy Forest Fire Spread in the Presence of Fire Breaks and Barriers

Technical Physics - In this paper, we studied the spreading of canopy forest fires in the presence of fire breaks and barriers consisting of hardwood trees by mathematical modeling. Mathematically,...     

Sensitivity of DNA Sensors in the Presence of Charged Ligands

Factors that influence both the thermodynamics of hybridization and the stability of the DNA–DNA duplexes are analyzed. The noncompetitive DNA hybridization cases in the presence of mono- and bivalent positively charged ligands have been investigated and the comparison is made with the case of uncharged ligands. It has been shown that the charged ligands enhance the sensitivity of the DNA chips as compared with the uncharged ones.     

Direct measurement of torque in an optical trap and its application to double-strand DNA

We present a method that offers the possibility to directly apply and measure torque on particles in an optical trap. It can be used to rotationally manipulate biopolymers attached to appropriate particles. A flat object is trapped and oriented in the focus of a linearly polarized laser light. The direction and power of the orientational trap are controlled by the polarization state of the light. As a demonstration of the capabilities of the method, we examined the torsional stiffness of dsDNA (lambda-DNA) in its linear torsional regime by directly measuring the torque generated by the molecule.     

全息曝光系统轴向调节误差对光栅衍射波像差的影响

光栅衍射波像差作为全息光栅重要的技术指标之一,直接影响光栅分辨率,其中曝光光学系统的调节误差是引起光栅衍射波像差的主要因素。采用q参数讨论了高斯光束在光栅曝光光学系统中的传播和变换,通过计算高斯光束经准直系统后的相位给出了叠栅条纹相位分布的解析表达式,由此系统分析了曝光系统调节误差与光栅衍射波像差的关系。理论分析结果表明:左右曝光光路准直系统的相对离焦对光栅衍射波像差的影响最为显著;相对离焦量相同时,光栅衍射波像差随曝光系统焦距的减小而逐渐增大;理论模拟的条纹分布与实验中获得的叠栅条纹能够很好吻合。     

Photostability of Cy3 and Cy5-Labeled DNA in the Presence of Metallic Silver Particles

We examined the photostability of a double-stranded DNA oligomer, covalently labeled with Cy3 or Cy5 on one strand, in the presence of metallic silver island films. In our experimental configuration a minor fraction of the labeled DNA was close to the silver particles and the remainder was distant from the particles. Proximity of the fluorophores to silver island films resulted in increased intensity. Upon continuous illumination we found a fraction of the emission that was resistant to the photobleaching. The emission spectra of the residual fractions were identical to the initial spectra. The frequency-domain lifetime measurements of this fraction revealed greatly shortened decay times. These results are consistent with the photostable fraction being close to the silver particles. This results suggest that the number of photons detected per fluorophore, prior to photobleaching, can be increased 5-fold or more by proximity to silver particles. Localization at an optimal distance from the silver surface may result in larger enhancements.     

Relaxation Kinetics of the Microhardness of KDP Crystals after Their Exposure to a Magnetic Field

It has been shown that potassium dihydrogen phosphate crystals change their microhardness reversibly after their exposure to a magnetic field of B = 0.8 or 1.2 T for t_m = 7–90 min. It has been found that the magnetic effect can be conveniently characterized by the quantity B²t_m, because the variation of the parameters conserving B²t_m=const does not change the result. At B²t_m < 10 T² min, the effect is almost absent. Above this threshold, the amplitude of changes in the microhardness increases and approaches a constant value of ~10% at B²t_m ≈ 19 T² min. The responses of samples of the same crystal from the faces of the prismatic and pyramidal growth sectors to exposure are different. In the former case, they soften; in the latter case, the hardening stage follows the softening stage. However, in both cases, the microhardness returns to the initial value. At B²t_m values from 19 to 37 T² min, the amplitudes and durations of the effect do not change, but in the narrow range of 37–43 T² min, the lifetime of the modified state increases sharply with transition to a new level: “sharp” peaks with a half-width of ~2 days are transformed to trapezoids with the width of the horizontal side of ~1–2 weeks. A physical scheme of the observed effects has been proposed.     

Mechanical Properties and Corrosion Resistance of Vulcanized Silicone Rubber after Exposure to Artificial Urine

Medical devices, such as Foley catheters, which are commonly fabricated from silicone rubber, need to have excellent mechanical properties and physiological inertness. This study reports the development of a facile method to prepare silicone rubber with excellent long-term performance by controlling the vulcanization procedure parameters only. Mechanical, viscoelastic, and chemical properties of vulcanized silicone rubber were investigated. The corrosion resistance of vulcanized silicone rubber was assessed by exposure to artificial body urine for a period of up to 14 days. The mechanical properties of silicone rubber were changed via adjusting the vulcanization procedure parameters. The improved mechanical properties of silicone rubber are attributed to an increase in crosslink density resulting from the proposed vulcanization technology. After 14 days of immersion in urine, no significant changes in mechanical properties and internal structure were observed. This indicated that the as-prepared rubber samples had high tear resistance and physiological inertness. These long-term properties are important for their applications as semi-permanent implant materials, such as Foley catheter balloons in clinics. Our process of vulcanization of silicone rubber may have potential for fabrication of such medical devices.     

Thermoelectric Properties of Single Molecule Junction in Presence of Dephasing and Different Coupling Geometries

The thermoelectric properties of a benzene molecule coupled to three-dimensional metallic electrodes are examined in the presence of dephasing processes using Green function formalism in the linear response regime. The three different kind of configurations(ortho, meta and para) are taken into account for the coupling between the molecule and electrodes. Results show that the thermoelectric properties of the single molecular junction are strongly dependent on the coupling geometry. Our results predict that the thermoelectric efficiency is increased in specific geometry as a consequence of interference effects. It is found that the dephasing effects result in the reduction of the thermoelectric efficiency.     

Thermoelectric Properties of Single Molecule Junction in Presence of Dephasing and Different Coupling Geometries

The thermoelectric properties of a benzene molecule coupled to three-dimensional metallic electrodes are examined in the presence of dephasing processes using Green function formalism in the linear response regime. The three different kind of configurations (ortho, meta and para) are taken into account for the coupling between the molecule and electrodes. Results show that the thermoelectric properties of the single molecular junction are strongly dependent on the coupling geometry. Our results predict that the thermoelectric efficiency is increased in specific geometry as a consequence of interference effects. It is found that the dephasing effects result in the reduction of the thermoelectric efficiency.     

Effect of DNA Synthesis Inhibitors on the Biological Efficiency of a Proton Beam in a Modified Bragg Peak

Physics of Particles and Nuclei Letters - The effect of the DNA synthesis inhibitors 1-β-D-arabinofuranosyl cytosine (AraC) and hydroxyurea (HU)—antitumor agents used in the...     

Critical Properties of Mixed Ising Spin System with Different Trimodal Transverse Fields in the Presence of Single-Ion Anisotropy

Within the framework of an effective field approximation, the effects of single-ion anisotropy and different trimodal transverse fields of two sublattices on the critical properties of the mixed spin-1/2 and spin-1 Ising system are investigated on the simple cubic lattice. A smaller single-ion anisotropy can magnify magnetic ordering phases and a larger one can depress magnetic ordering phase for T-Ω_1/2 space at low temperatures, while a smaller single-ion anisotropy can hardly change the value of critical transverse field for T-Ω₁ space. On the other hand, influences of two different trimodal transverse fields concentrations on tricritical points and magnetic ordering phases take on some interesting results in T-D space. The main reason comes from the common action of single-ion anisotropy, different transverse fields and two trimodal distributions.     

Efficiency of Locking of a Long-Living Photon-Echo Response in the Presence of External Nonresonant Laser Pulses with Different Spatial Inhomogeneity

We study correlations between the inhomogeneous line broadening and the efficiency of locking of a long-living photon-echo response. We show that the efficiency of locking of a long-living photon-echo signal depends weakly on the spatial inhomogeneity of nonresonant laser pulses.     

Active Inference: Applicability to Different Types of Social Organization Explained through Reference to Industrial Engineering and Quality Management

Active inference is a physics of life process theory of perception, action and learning that is applicable to natural and artificial agents. In this paper, active inference theory is related to different types of practice in social organization. Here, the term social organization is used to clarify that this paper does not encompass organization in biological systems. Rather, the paper addresses active inference in social organization that utilizes industrial engineering, quality management, and artificial intelligence alongside human intelligence. Social organization referred to in this paper can be in private companies, public institutions, other for-profit or not-for-profit organizations, and any combination of them. The relevance of active inference theory is explained in terms of variational free energy, prediction errors, generative models, and Markov blankets. Active inference theory is most relevant to the social organization of work that is highly repetitive. By contrast, there are more challenges involved in applying active inference theory for social organization of less repetitive endeavors such as one-of-a-kind projects. These challenges need to be addressed in order for active inference to provide a unifying framework for different types of social organization employing human and artificial intelligence.     

可见光谱照明对小鼠卵母细胞及早期胚胎发育质量的影响

卵母细胞及早期胚胎在体外提取时难免受到可见光照明的刺激。但光照明对其体外发育质量的影响仍不明确。结合体外培养技术、无损成像技术(全场光学相干层析系统)及三维重构技术,在光强与曝光时间一致的条件下,首次实时原位地,从形态学角度,分析了不同可见光谱对小鼠卵母细胞及早期胚胎发育质量的影响。发现(1)与白光照明相比,蓝紫光显著降低卵母细胞生发泡破裂及第一极体排出比率,而在绿光及红光照明下,生发泡破裂及第一极体排出比率明显提高。(2)与白光组相比,蓝紫光组囊胚发生率明显下降,凋亡程度明显加大,而绿光及红光组囊胚发生率显著上调,凋亡程度明显减弱。这表明蓝紫光对小鼠卵母细胞及早期胚胎发育的损伤最大,而绿光和红光几乎无损伤。     

Changes in the Functional Activity of Platelets during Experimental Exposure to Prolonged Photoperiod

Optics and Spectroscopy - Effects of excessive exposure to light on platelet aggregation activity were studied in white male rats using the Light–Dark (18 : 6) photoperiod model. Platelet...