Finite Matrix Groups over Nilpotent Group Rings

AbstractWe study groups of matricesSGLn(ZΓ) of augmentation one over the integral group ring ZΓ of a nilpotent group Γ. We relate the torsion ofSGLn(ZΓ) to the torsion of Γ. We prove that all abelianp-subgroups ofSGLn(ZΓ) can be stably diagonalized. Also, all finite subgroups ofSGLn(ZΓ) can be embedded into the diagonal Γn<SGLn(ZΓ). We apply matrix results to show that if Γ is nilpotent-by-(Π′-finite) then all finite Π-groups of normalized units in ZΓ can be embedded into Γ

Separation of variables in quasi-potential systems of bi-cofactor form

We perform variable separation in the quasi-potential systems of equations of the form $\ddot{q}=-A^{-1}\nabla k=-\tilde{A}^{-1}\nabla\tilde{k}${}, where $A$ and $\tilde{A}$ are Killing tensors, by embedding these systems into a bi-Hamiltonian chain and by calculating the corresponding Darboux-Nijenhuis coordinates on the symplectic leaves of one of the Hamiltonian structures of the system. We also present examples of the corresponding separation coordinates in two and three dimensions.Comment: LaTex, 30 pages, to appear in J. Phys. A: Math. Ge

Luminescence based temperature bio-imaging: Status, challenges, and perspectives

The only way to get thermal images of living organisms without perturbing them is to use luminescent probes with temperature-dependent spectral properties. The acquisition of such thermal images becomes essential to distinguish various states of cells, to monitor thermogenesis, to study cellular activity, and to control hyperthermia therapy. Current efforts are focused on the development and optimization of luminescent reporters such as small molecules, proteins, quantum dots, and lanthanide-doped nanoparticles. However, much less attention is devoted to the methods and technologies that are required to image temperature distribution at both in vitro or in vivo levels. Indeed, rare examples can be found in the scientific literature showing technologies and materials capable of providing reliable 2D thermal images of living organisms. In this review article, examples of 2D luminescence thermometry are presented alongside new possibilities and directions that should be followed to achieve the required level of simplicity and reliability that ensure their future implementation at the clinical level. This review will inspire specialists in chemistry, physics, biology, medicine, and engineering to collaborate with materials scientists to jointly develop novel more accurate temperature probes and enable mapping of temperature with simplified technical mean

Antioxidant capacity and physical exercise

The aim of this article is a presentation of current knowledge regarding the changes of plasma antioxidant capacity observed in response to physical exercise. Human body created the enzymatic and non-enzymatic systems, which play a protective role in the harmful impact of free radicals. Those two systems constitute what is known as the plasma total antioxidant capacity. The amount of reactive oxygen species (ROS) and reactive nitrogen species (NOS) in combination with oxidation processes increases in some tissues during physiological response to physical exercise. These changes are observed after single bout of exercise as well as after regular training. The response of human body to physical exercise can be analysed using various models of exercise test. Application of repeated type of exhaustion allows for characterizing the ability of human body to adjust to the increased energy loss and increased oxygen consumption. This article presents the characteristics of components of plasma antioxidant capacity, the mechanisms of free radicals production and their role in human body. It discusses also the currently used methods of detecting changes in total antioxidant capacity and its individual elements in response to single bout of exercise and regular training. It presents the review of literature about research performed in groups of both regularly training and low exercise activity individuals as well as in group of healthy subjects and patients with circulation diseases

Dispersion monitoring for high-speed WDM networks via two-photon absorption in a semiconductor microcavity

Due to the continued demand for bandwidth, network operators have to increase the data rates at which individual wavelengths operate at. As these data rates will exceed 100 Gbit/s in the next 5-10 years, it will be crucial to be able to monitor and compensate for the amount of chromatic dispersion encountered by individual wavelength channels. This paper will focus on the use of the novel nonlinear optical-to-electrical conversion process of two-photon absorption (TPA) for dispersion monitoring. By incorporating a specially designed semiconductor microcavity, the TPA response becomes wavelength dependent, thus allowing simultaneous channel selection and monitoring without the need for external wavelength filterin

Nonlinearities in the reflection and transmission spectra of the photonic bandgap heterostructures with n–i–p–i crystals

Nonlinear optical properties of photonic crystal heterostructures with embedded n–i–p–i superlattices are investigated. Self-consistent calculations of the transmission and reflection spectra near the defect mode are performed using the transfer-matrix method and taking into account the gain saturation. Analysis of features and output characteristics is carried out for one-dimensional photonic crystal heterostructure amplifiers in the GaAs–GaInP system having at the central part an active “defect” from doubled GaAs n–i–p–i crystal layers. The gain saturation in the active layers in the vicinity of the defect changes the index contrast of the photonic structure and makes worse the emission at the defect mode. Spectral bistability effect, which can be exhibited in photonic crystal heterostructure amplifiers, is predicted and the hysteresis loop and other attending phenomena are described. The bistability behavior and modulation response efficiency demonstrate the potential possibilities of the photonic crystal heterostructures with n–i–p–i layers as high-speed optical amplifiers and switches

Wpływ ondansetronu na parametry hemodynamiczne matki podczas znieczulenia podpajęczynówkowego do cięcia cesarskiego – badanie randomizowane, przeprowadzone metodą podwójnie ślepej próby

Objective: verification of a hypothesis assuming that 5-HT3 receptor blockade by intravenous administration of ondansetron reduces the incidence of hypotension and bradycardia in patients undergoing spinal anaesthesia for Caesarean section. Material and methods: The study design was approved by the Bioethics Committee and included 72 patients undergoing elective Caesarean section, randomly assigned to ondansetron group (group O) or placebo group (group P). Finally, group O encompassed 35 patients administered ondansetron 8 mg i.v. dissolved in 10ml 0.9% NaCl whereas group P consisted of 34 patients receiving 0.9% NaCl 10 mg. Systolic and diastolic pressures were measured every 2 minutes since the onset of anaesthesia. Heart rate (HR) was monitored continuously. The criterion of hypotension requiring ephedrine was a decrease in systolic pressure by 20% compared to its baseline value or a decrease in systolic pressure below 90 mm Hg. The criterion of bradycardia was a decrease in HR below 60/min. Results: Hypotension was observed in 14 group O patients (39%) and in 15 group P patients (44%); the difference was not statistically significant. Bradycardia was noted in 1 group O patient (3%) and in 2 group P patients (6%); the difference was not statistically significant. Conclusion: A hypothesis assuming a reduction in pressure following subarachnoid anaesthesia for Caesarean section after the administration of 8 mg of ondansetron was not confirmed.Cel pracy: weryfikacja hipotezy zakładającej, że blokada receptorów 5-HT3 poprzez dożylne podanie ondansetronu redukuje częstość występowania hipotensji i bradykardii u pacjentek znieczulanych podpajęczynówkowo do cięcia cesarskiego. Materiał i metodyka: Plan badań uzyskał zgodę komisji bioetycznej. Do badania zakwalifikowano 72 pacjentki poddawane planowemu cięciu cesarskiemu, losowo przydzielając je do grupy ondansetronu (grupa O) lub grupy placebo (grupa P). Ostatecznie grupa O liczyła 36 pacjentek, którym przed znieczuleniem podano dożylnie 8 mg ondansetronu rozcieńczonego w 10 ml 0,9% NaCl, grupa P liczyła 34 pacjentki, które otrzymały 10 ml 0,9% NaCl. Pomiaru skurczowego i rozkurczowego ciśnienia tętniczego krwi dokonywano co 2 minuty od momentu znieczulenia. Częstość akcji serca (HR) monitorowana była w sposób ciągły. Za kryterium hipotensji wymagającej podania efedryny przyjęto spadek ciśnienia skurczowego o 20% w porównaniu z ciśnieniem wyjściowym lub spadek ciśnienia skurczowego poniżej 90 mm Hg. Za kryterium bradykardii przyjęto spadek akcji serca poniżej 60/min. Wyniki: Hipotensję zanotowano u 14 pacjentek w grupie O (39%) i u 15 pacjentek w grupie P (44%) co nie stanowiło statystycznie istotnej różnicy. Bradykardię zanotowano u 1 pacjentki w grupie O (3%) i u 2 pacjentek w grupie P (6%) co nie stanowiło statystycznie istotnej różnicy. Wnioski: Nie potwierdzono przyjętej hipotezy zakładającej redukcję spadku ciśnienia po znieczuleniu podpajęczynówkowym do cięcia cesarskiego po podaniu 8 mg Ondansetronu

Nonlinear gain and bistability in photonic crystal heterostructures with compositional and doping superlattices

Optical properties of photonic crystal heterostructures with embedded n–i–p–i superlattices are studied. Nonlinear behavior of the transmission and reflection spectra near the defect mode is investigated. Self-consistent calculations of the output performance characteristics are performed using the transfer-matrix method and taking into account the gain saturation. Features and characteristic parameters of the nonlinear gain in active n–i–p–i layers are determined. Detail analysis of the gain saturation and accompanying nonlinear refraction effects is carried out for one-dimensional photonic crystal heterostructure amplifiers in the GaAs–GaInP system having at the central part an active “defect” from the doubled GaAs n-i-p-i crystal. The gain saturation in the active layers in the vicinity of the defect changes the index contrast of the photonic structure and makes worse the emission at the defect mode. Spectral bistability effect which can be exhibited in photonic crystal heterostructure amplifiers is predicted and the hysteresis loop and other attending phenomena are described. The bistability behavior and modulation response efficiency demonstrate the potential possibilities of the photonic crystal heterostructures with n-i-p-i layers as high-speed optical amplifiers and switches