Log-log growth of channel capacity for nondispersive nonlinear optical fiber channel in intermediate power range: Extension of the model.

In our previous paper [Terekhov et al., Phys. Rev. E 95, 062133 (2017)2470-004510.1103/PhysRevE.95.062133] we considered the optical channel modeled by the nonlinear Schrödinger equation with zero dispersion and additive Gaussian noise. We found per-sample channel capacity for this model. In the present paper we extend the per-sample channel model by introducing the initial signal dependence on time and the output signal detection procedure. The proposed model is a closer approximation of the realistic communications link than the per-sample model where there is no dependence of the initial signal on time. For the proposed model we found the correlators of the output signal both analytically and numerically. Using these correlators we built the conditional probability density function. Then we calculated an entropy of the output signal, a conditional entropy, and the mutual information. Maximizing the mutual information we found the optimal input signal distribution, channel capacity, and their dependence on the shape of the initial signal in the time domain for the intermediate power range.

Self-Induced Faraday Instability Laser.

We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously caused by the presence of pump depletion, which leads to a periodic gain landscape for light propagating in the cavity. As a result of the instability, continuous wave oscillation becomes unstable even in the normal dispersion regime of the cavity, and a periodic train of pulses with ultrahigh repetition rate is generated. Application to the case of Raman fiber lasers is described, in good quantitative agreement between our conceptual analysis and numerical modeling.

Generation of spatio-temporal extreme events in noise-like pulses NPE mode-locked fibre laser.

We experimentally study spatio-temporal generation of extreme events in the radiation of NPE mode-locked fibre laser generating noise-like pulses. We show that new pulses starts from high-intensity spatio-temporal structure which consist of mainly 3 subsequent pulses which are both separated over fast and slow evolution time. Statistical analysis of the noise-like pulse evolution over round-trips shows that the pulse width and intensity varies with a period of around 85 round-trips which does not change from pulse to pulse. The intensity probability density function has a heavy tail originated only from events of pulse formation.

Secure polarization-independent subcarrier quantum key distribution in optical fiber channel using BB84 protocol with a strong reference.

A quantum key distribution system based on the subcarrier wave modulation method has been demonstrated which employs the BB84 protocol with a strong reference to generate secure bits at a rate of 16.5 kbit/s with an error of 0.5% over an optical channel of 10 dB loss, and 18 bits/s with an error of 0.75% over 25 dB of channel loss. To the best of our knowledge, these results represent the highest channel loss reported for secure quantum key distribution using the subcarrier wave approach. A passive unidirectional scheme has been used to compensate for the polarization dependence of the phase modulators in the receiver module, which resulted in a high visibility of 98.8%. The system is thus fully insensitive to polarization fluctuations and robust to environmental changes, making the approach promising for use in optical telecommunication networks. Further improvements in secure key rate and transmission distance can be achieved by implementing the decoy states protocol or by optimizing the mean photon number used in line with experimental parameters.

[Ontogenetic Mechanisms of Explosive Morphological Divergence in the Lake Tana (Ethiopia) Species Flock of Large African Barbs (Labeobarbus; Cyprinidae; Teleostei)].

Species flock of Lake Tana (Ethiopia) large African barbs (Labeobarbus; Cyprinidae; Teleostei) was studied as a model system for investigating ontogenetic mechanisms of the explosive morphological divergence often accompanying sympatric speciation in bony fishes. Comparative morphological analysis carried out with the use ofgeometric morphometric techniques revealed quantitative differences in the head shapes of species under study. Comparative analysis of skull development revealed significant interspecies differences in the temporal characteristics of craniogenesis in these species. These two lines of evidence suggest that heterochronies in craniogenesis underlie divergence in the head shapes of adult Tana barbs. This prediction was verified via experimental changes of temporal characteristics of craniogenesis in L. intermedius, a putative ancestor for the Lake Tana species flock. For this aim, timing and rate of skull development were changed by artificial manipulation of thyroid hormone levels. In sum, it was shown that it is heterochronies that underlie an explosive morphological divergence of the Lake Tana barbs species flock. Our findings together with those reported in the literature suggest variability in the activity of the hypothalamic-pituitary-thyroid axis to contribute to these heterochronies.

[Correlation between biochemical parameters of oxidative stress, endogenous intoxication and regulation of vascular tone in patients with burn injury].

Burn injury is accompanied by the formation of reactive oxygen species (ROS). Excessive production of ROS results in oxidative stress. Peroxidation damage of proteins causes their degradation and the formation of toxic fragments con- tributing to the development of endogenous intoxication. Furthermore, burns cause pronounced inflammatory reaction in the lesion site leading to poor circulation. The purpose of this study was an investigation of relationship between disturbances in the prooxidant/antioxidant system, severity of endogenous intoxication and disturbances of endogenous vascular regulation to assess the severity and prognosis of complications in patients with burn injury. 26 patients with- burn injury were investigated; they were divided into 2 groups according to the severity of injury on the basis of Frank index (FI): group 1--FI < 60 CU and group 2--FI ≥ 60 CU. The investigation of blood serum was performed on 1-3, 7, 14, 21 and 28 day after burn injury. Malondialdehyde (MDA), total antioxidant status (TAS), the level of middle weight molecules, stable metabolites of nitric oxide (NOx) and angiotensin-converting enzyme (ACE) activity were determined in the serum. Significant increase of MDA level, decrease of TAS and NOx level were found in two groups of patients throughout the observation period. We also found a disturbance in coupled interaction of NO and ACE. These data point to the development of oxidative stress and imbalance in endogenous regulation of vascular tone. There was a trend toward more pronounced oxidative stress in group 2. Significant correlations between parameters of oxidative stress, endogenous intoxication, endogenous factors of vascular regulation, depth of burn injury and FI were obtained in two groups. MDA, TAS can serve as one of the prognostic markers of condition severity of burned patients and therapy adequacy.

Stochasticity, periodicity and localized light structures in partially mode-locked fibre lasers.

Physical systems with co-existence and interplay of processes featuring distinct spatio-temporal scales are found in various research areas ranging from studies of brain activity to astrophysics. The complexity of such systems makes their theoretical and experimental analysis technically and conceptually challenging. Here, we discovered that while radiation of partially mode-locked fibre lasers is stochastic and intermittent on a short time scale, it exhibits non-trivial periodicity and long-scale correlations over slow evolution from one round-trip to another. A new technique for evolution mapping of intensity autocorrelation function has enabled us to reveal a variety of localized spatio-temporal structures and to experimentally study their symbiotic co-existence with stochastic radiation. Real-time characterization of dynamical spatio-temporal regimes of laser operation is set to bring new insights into rich underlying nonlinear physics of practical active- and passive-cavity photonic systems.

Linear compression of chirped pulses in optical fibre with large step-index mode area.

The possibilities and limitations of linear compression of positively chirped pulses in the negative-dispersion region of a step-index large mode-area single-mode optical fibre are investigated for the first time. Analytical formulae for critical values of radiation power are found, below which pedestal-free pulse compression is possible down to the Fourier limit. It is demonstrated that at radiation powers exceeding these critical values, there exists an optimal compressing fibre length, over which laser pulses reach the minimum of the time-bandwidth product, and beyond which irreversible pulse deformation occurs. The modelling results agree well with the experimental data.

TRPM4 inhibitor 9-phenanthrol activates endothelial cell intermediate conductance calcium-activated potassium channels in rat isolated mesenteric artery.

BACKGROUND AND PURPOSE: Smooth muscle transient receptor potential melastatin 4 (TRPM4) channels play a fundamental role in the development of the myogenic arterial constriction that is necessary for blood flow autoregulation. As TRPM4 channels are present throughout the vasculature, we investigated their potential role in non-myogenic resistance arteries using the TRPM4 inhibitor 9-phenanthrol. EXPERIMENTAL APPROACH: Pressure and wire myography were used to assess the reactivity of rat arteries, the latter in combination with measurements of smooth muscle membrane potential. Immunohistochemistry (IHC) and endothelial cell (EC) calcium changes were assessed in pressurized vessels and patch clamp measurements made in isolated ECs. KEY RESULTS: The TRPM4 inhibitor 9-phenanthrol reversibly hyperpolarized mesenteric arteries to circa EK and blocked α1 -adrenoceptor-mediated vasoconstriction. Hyperpolarization was abolished and vasoconstriction re-established by damaging the endothelium. In mesenteric and cerebral artery smooth muscle, 9-phenanthrol hyperpolarization was effectively blocked by the KCa 3.1 inhibitor TRAM-34. 9-Phenanthrol did not increase mesenteric EC [Ca(2+)]i , and Na(+) substitution with N-methyl-D-glucamine only increased the muscle resting potential by 10 mV. Immunolabelling for TRPM4 was restricted to the endothelium and perivascular tissue. CONCLUSIONS AND IMPLICATIONS: These data reveal a previously unrecognized action of the TRPM4 inhibitor 9-phenanthrol - the ability to act as an activator of EC KCa 3.1 channels. They do not indicate a functionally important role for TRPM4 channels in the reactivity of non-myogenic mesenteric arteries.

Experimental substantiation and clinical use of a combination of dermal matrix with allogenic or autologous cells for the treatment of extensive traumatic wounds.

We carried out a comparative experimental and clinical study of the efficiency of the combination of dermal matrix with autologous and allogenic cells for creation of an optimal biological wound coating. Experiments on outbred mice have demonstrated that the use of dermal matrix in combination with allogeneic or autologous cells shortens the inflammation phase and accelerated maturation of the granulation tissue. Clinical application of biological wound dressing based on dermal matrix in combination with autologous or allogeneic mesenchymal multipotent stromal cells prevented septic complications and shortened the time of preparing extensive traumatic wounds with skin defect to autodermoplasty.

Thyroid hormones in the skeletogenesis and accessory sources of endogenous hormones in Xenopus laevis (Amphibia; Anura) ontogeny: Experimental evidence.

Skeletal development was studied in normal and goitrogen-treated Xenopus laevis tadpoles reared under thyroid hormone (TH) deficiency. Early stages of skeletal development proceed similarly in both groups. Later stages are retarded or completely arrested in goitrogen-treated tadpoles. After goitrogen-treated tadpoles were transferred into pure water or into a medium containing both goitrogen and exogenous TH, tadpoles resumed development. Consequently, late stages of skeletogenesis are TH-dependent and TH-induced. Athyroid X. laevis "giant tadpoles" described in literature differ from goitrogen-arrested tadpoles in that they have features which require TH to appear. The appearance of TH-depended features in giant tadpoles indicates the occurrence of the additional sources of TH other than thyroid gland.

High average power mode-locked figure-eight Yb fibre master oscillator.

For the first time, we demonstrate the possibility to generate record-high output radiation power exceeding 1 W in an all-fibre figure-eight mode-locked Yb fibre master oscillator based on non-linear amplifying loop mirror. Generated at the repetition rate of 25 MHz clusters of sub-pulses with duration of no more than 200 fs have envelope width of 23 ps or less. Two typical mode-locked laser regimes with substantially different generation spectra are identified and results of their study presented. Numerical modelling of laser generation in the proposed layout agrees well with the measured experimental data.

[Stepwise treatment in patients with isolated thermal inhalation injury].

AIM: To evaluate the efficiency of stepwise treatment in patients with isolated thermal inhalation injury (TIJ). SUBJECTS AND METHODS: The study enrolled 101 patients with isolated TIJ. A study group (n=56) was treated at the Pulmonology Department after managing at the Burn Center (BC); a control group (n=45) received no systematic treatment after discharging from BC. The magnitude of respiratory symptoms (according to the rating system) and external respiratory function (ERF) was evaluated and fibrobronchoscopy was made in all the included patients at their discharge from BC. On admission to the Pulmonology Department, the study group patients underwent evaluation of the magnitude of respiratory symptoms, EFR, and lung diffusing capacity, determination of blood gas composition and exercise tolerance, and chest computed tomography. Respiratory symptoms, ERF, and exercise tolerance were evaluated in all the included patients one month after hospital discharge. RESULTS: Examination at the Pulmonology Department established preserved respiratory manifestations in patients who had to continue therapy. The use of beta2-agonists or inhaled steroids used in combination or alone need, mucoregulators or antibiotics revealed the efficiency of a stepwise approach to managing patients with TIJ. CONCLUSION: There is evidence that it is expedient to perform two-stage treatment in patients with TIJ, by transferring them from BC to a specialized pulmonology hospital, which substantially enhances the efficiency of medical care for this contingent of patients.

[The dynamics of endogenic intoxication in patients with extensive burns].

The sampling consisted of 22 patients with extensive burns with total affected area from 20% to 84% of body surface and with deep burns area from 10% to 40%. The suppurative complications in the form of sepsis were diagnosed in 10 and the transitory bacteremia in 12 victims. The total and effective concentration of albumin, the content of medium molecular peptides in dynamics at 1-3, 7, 14 and 21 days from the moment of trauma were detected to objectively evaluate the endogenic intoxication. The degree of intensity of endogenic intoxication was studied using such integral indicator as effective utilization factor In patients with extensive burns the endogenic intoxication was diagnosed on the basis of total and effective concentration of albumin and increase of content of medium molecular peptides. However the detection of endogenic intoxication of the basis of effective utilization factor is a more informative as compared with the analysis of these indicators separately and, hence, it promote the prescription of more appropriate disintoxication therapy its effectiveness evaluation including.

[Novel NADPH-dependent L-aspartate dehydrogenases from the mesophilic nitrogen-fixing bacteria Rhodopseudomonas palustris and Bradyrhizobium japonicum].

The genes encoding putative L-aspartate dehydrogenases (EC 1.4.1.21, ADH) from the mesophilic nitrogen-fixing bacteria Rhodopseudomonas palustris and Bradyrhizobium japonicum were cloned and expressed in Escherichia coli. The respective enzymes in the form of hybrid proteins with N-terminal hexahistidine tags were purified to apparent homogeneity. Both enzymes catalyzed in vitro the reductive amination of oxaloacetate to L-aspartate by an order faster than the reverse reaction at a respective pH optimum of 8.0-9.0 and 9.8; also, the enzymes only catalyzed amination under physiological conditions (pH 7.0-8.0). Their specificity to NADPH was higher by 1-2 orders of magnitude than that to NADH. The apparent KM values of ADHs from R. palustris for oxaloacetate, ammonium, and NADPH at pH 9.0 were 9.2, 11.3, and 0.21 mM, respectively, and the corresponding KM values of ADH from B. japonicum were 21, 4.3, and 0.032 mM, respectively. The amination activity of novel ADHs may be important for the fixation of inorganic nitrogen in vivo and used for the construction of a bacterial strain-producer of L-aspartate by metabolic engineering methods.

Generation dynamics of the narrowband Yb-doped fiber laser.

We present direct real-time experimental measurements and numerical modeling of temporal and statistical properties for the Ytterbium-doped fiber laser with spectral bandwidth of ~2 GHz. The obtained results demonstrate nearly exponential probability density function for intensity fluctuations. A significant decrease below the Gaussian probability has been experimentally observed for intensity fluctuations having value more than 2.5 of average intensity that may be treated as indication of some mode correlations.

ß1-Adrenoceptor stimulation suppresses endothelial IK(Ca)-channel hyperpolarization and associated dilatation in resistance arteries.

BACKGROUND AND PURPOSE: In small arteries, small conductance Ca²âº-activated K⁺ channels (SK(Ca)) and intermediate conductance Ca²âº-activated K⁺ channels (IK(Ca)) restricted to the vascular endothelium generate hyperpolarization that underpins the NO- and PGI2-independent, endothelium-derived hyperpolarizing factor response that is the predominate endothelial mechanism for vasodilatation. As neuronal IK(Ca) channels can be negatively regulated by PKA, we investigated whether ß-adrenoceptor stimulation, which signals through cAMP/PKA, might influence endothelial cell hyperpolarization and as a result modify the associated vasodilatation. EXPERIMENTAL APPROACH: Rat isolated small mesenteric arteries were pressurized to measure vasodilatation and endothelial cell [Ca²âº]i , mounted in a wire myograph to measure smooth muscle membrane potential or dispersed into endothelial cell sheets for membrane potential recording. KEY RESULTS: Intraluminal perfusion of ß-adrenoceptor agonists inhibited endothelium-dependent dilatation to ACh (1 nM-10 µM) without modifying the associated changes in endothelial cell [Ca²âº]i . The inhibitory effect of ß-adrenoceptor agonists was mimicked by direct activation of adenylyl cyclase with forskolin, blocked by the ß-adrenoceptor antagonists propranolol (non-selective), atenolol (ß1) or the PKA inhibitor KT-5720, but remained unaffected by ICI 118 551 (ß2) or glibenclamide (ATP-sensitive K⁺ channels channel blocker). Endothelium-dependent hyperpolarization to ACh was also inhibited by ß-adrenoceptor stimulation in both intact arteries and in endothelial cells sheets. Blocking IK(Ca) {with 1 µM 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34)}, but not SK(Ca) (50 nM apamin) channels prevented ß-adrenoceptor agonists from suppressing either hyperpolarization or vasodilatation to ACh. CONCLUSIONS AND IMPLICATIONS: In resistance arteries, endothelial cell ß1-adrenoceptors link to inhibit endothelium-dependent hyperpolarization and the resulting vasodilatation to ACh. This effect appears to reflect inhibition of endothelial IK(Ca) channels and may be one consequence of raised circulating catecholamines.

A novel Fe(II)/α-ketoglutarate-dependent dioxygenase from Burkholderia ambifaria has ß-hydroxylating activity of N-succinyl l-leucine.

An Fe(II)/α-ketoglutarate-dependent dioxygenase, SadA, was obtained from Burkholderia ambifaria AMMD and heterologously expressed in Escherichia coli. Purified recombinant SadA had catalytic activity towards several N-substituted l-amino acids, which was especially strong with N-succinyl l-leucine. With the NMR and LC-MS analysis, SadA converted N-succinyl l-leucine into N-succinyl l-threo-ß-hydroxyleucine with >99% diastereoselectivity. SadA is the first enzyme catalysing ß-hydroxylation of aliphatic amino acid-related substances and a potent biocatalyst for the preparation of optically active ß-hydroxy amino acids.

Morphofunctional evaluation of the effect of transplantation of allogeneic fibroblasts on healing of burn wounds in albino outbred mice and mutant Hr(hr)/Hr(hr) mice.

Morphofunctional evaluation of the effect of transplantation of allogeneic fibroblasts on skin regeneration after burn injury in albino outbred mice and mutant Hr(hr)/Hr(hr) (nude) mice was carried out using the radioautographic method. The pronounced stimulating effect of allogeneic fibroblasts on healing of burn wound observed in mice of both groups can be attributed to the action of bioactive substances released from destructed allogeneic fibroblasts and stimulating proliferation of stem/progenitor cells in the wound (epithelial cells in skin appendages and dermal cells in microvessel walls) at the early stages of healing.