We demonstrate how the pitchfork, transcritical and saddle-node bifurcations of steady states observed in dynamical systems with a finite number of isolated equilibrium points occur in systems with ...lines of equilibria. The exploration is carried out by using the numerical simulation and linear stability analysis applied to a model of a memristor-based circuit. All the discussed bifurcation scenarios are considered in the context of models with the piecewise-smooth memristor current-voltage characteristic (Chua’s memristor), as well as on examples of oscillators with the memristor nonlinearity that is smooth everywhere. Finally, we compare the dynamics of ideal-memristor-based oscillators with the behavior of models taking into account the memristor forgetting effect. The presented results are obtained for electronic circuit models, but the studied bifurcation phenomena can be exhibited by systems with lines of equilibria of any nature.
The paper considers the new effects of the nanoscale state of matter, which open up prospects for the development of electronic devices using new physical principles. The contacts of chemically ...homogeneous nanoparticles of yttrium-stabilized zirconium oxide (ZrO2—x mol% Y2O3, x = 0, 3, 4, 8; YSZ) with different sizes of 7.5 nm and 9 nm; 7.5 nm and 11 nm; and 7.5 nm and 14 nm, respectively, was studied on direct current using nanostructured objects in the form of compacts obtained by high-hydrostatic pressure (HP-compacts of 300MPa). A unique size effect of the nonlinear (rectifying-type contact) dependence of the electrical properties (in the region U < 2.5 V, I ≤ 2.7 mA) of the contact of different-sized YSZ nanoparticles of the same chemical composition is revealed, which indicates the possibility of creating semiconductor structures of a new type (homogeneous electronics). The electronic structure of the near-surface regions of nanoparticles of studied oxide materials and the possibility of obtaining specifically rectifying properties of the contacts were studied theoretically. Models of surface states of the Tamm-type are constructed considering the Coulomb long-range action. The discovered energy variance and its dependence on the curvature of the surface of nanoparticles made it possible to study the conditions for the formation of a contact potential difference in cases of nanoparticles of the same radius (synergistic effect), different radii (doped and undoped variants), as well as to discover the possibility of describing a group of powder particles within the Anderson model. The determined effect makes it possible to solve the problem of diffusion instability of semiconductor heterojunctions and opens up prospects for creating electronic devices with a fundamentally new level of properties for use in various fields of the economy and breakthrough critical technologies.
As the most abundant protein with a variety of physiological functions, albumin has been used extensively for the delivery of therapeutic molecules. Thiolactone chemistry provides a powerful tool to ...prepare spin-labeled albumin-based multimodal imaging probes and therapeutic agents. We report the synthesis of a tamoxifen homocysteine thiolactone derivative and its use in thiol-'click' chemistry to prepare multi-functionalized serum albumin. The released sulfhydryl group of the homocysteine functional handle was labeled with a nitroxide reagent to prepare a spin-labeled albumin-tamoxifen conjugate confirmed by MALDI-TOF-MS, EPR spectroscopy, UV-vis and fluorescent emission spectra. This is the basis for a novel multimodal tamoxifen-albumin theranostic with a significant (dose-dependent) inhibitory effect on the proliferation of malignant cells. The response of human glioblastoma multiforme T98G cells and breast cancer MCF-7 cells to tamoxifen and its albumin conjugates was different in tumor cells with different expression level of ERα in our experiments. These results provide further impetus to develop a serum protein for delivery of tamoxifen to cancer cells.
A tamoxifen-homocysteine conjugate provides a tool to prepare a multifunctionalized albumin theranostic with a significant cytotoxicity on the malignant cells.
Here, we report the pediatric cases of sitosterolemia, a rare autosomal-recessive genetic disorder, characterized by high concentrations of plant sterols in blood and heterogeneity manifestations. ...All three patients (two girls aged 2 and 6 years old, and one boy aged 14 years old) were initially diagnosed with hypercholesterinemia. Next-generation sequencing (NGS) revealed homozygous (p.Leu572Pro/p.Leu572Pro) and compound (p.Leu572Pro/p.Gly512Arg and p.Leu572Pro/p.Trp361*) variants in the ABCG8 gene that allowed for the diagnosis of sitosterolemia. Two patients whose blood phytosterol levels were estimated before the diet demonstrated high levels of sitosterol/campesterol (69.6/29.2 and 28.3/12.4 μmol/L, respectively). Here, we demonstrate that NGS-testing led to the proper diagnosis that is essential for patients’ management. The variant p.Leu572Pro might be prevalent among patients with sitosterolemia in Russia.
Background. The obvious expansion of mini-invasive technologies is looming large in surgical treatment of heart diseases. Hundreds of thousands of transcatheter aortic valve replacement procedures ...have been performed in the world today. The improvement in quality and the increase in life expectancy in cohorts of patients who until recently have been considered inoperable are now routinely achievable. A significant limitation of this method for Russian clinics is the absence of domestic transcatheter implantable prosthetic heart valves on the market. During the last five years, such devices have been developed at “MedEng” (Penza, Russia) scientific and production enterprise. We present the first Russian transcatheter aortic valve prosthesis, its leaflets made of polytetrafluoroethylene, components of the delivery system and implantation, as well as the hospital outcomes of clinical trials. Aim. To evaluate the clinical and hemodynamic results of transcatheter aortic valve implantation using a “MedLab-KT” prosthesis during hospital stay.Methods. A prospective study included 54 patients who underwent transcatheter repair of the aortic valve using a “MedLab-KT” prosthesis. To evaluate the frequency of complications, myocardial infarction, strokes, bleeding, deaths during hospital stay and gradient indices on the prosthesis, postoperative ultrasound examination data were obtained and analyzed. Results. The results are comparable with those achieved by using the foreign models known from literature. Conclusion. The clinical and hemodynamic results of using the “MedLab-KT” aortic valve prosthesis can be considered as satisfactory. Funding: The study had no sponsorship. Conflict of interest: The authors declare no conflict of interest. Authors’ contributionConception and study design: V.V. Bazylev, E.V. Rosseykin, A.B. VoevodinData collection and analysis: A.B. Voevodin, A.S. ZakharovaStatistical analysis: A.B. VoevodinDrafting the article: A.B. VoevodinCritical revision of the article: A.B. VoevodinFinal approval of the version to be published: V.V. Bazylev, A.B. Voevodin, A.S. Zakharova, E.V. Rosseykin ORCID IDV.V. Bazylev, https://orcid.org/0000-0001-6089-9722A.B. Voevodin, https://orcid.org/0000-0002-7078-1274A.S. Zakharova, https://orcid.org/0000-0001-7239-2945E.V. Rosseykin, https://orcid.org/0000-0003-0784-2246
The influence of white and colored noise on the dynamics of self-sustained oscillator is considered in the regime of spiral (phase-coherent) chaos. The effective phase diffusion coefficient and power ...spectra are analyzed for noisy chaotic self-sustained oscillations. We show that chaotic oscillations can be synchronized by external narrow-band noise. Effects of chaos synchronization are compared for narrow-band noise signals with similar spectra but distinct probability distributions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
STUDY QUESTION
How did coronavirus disease 2019 (COVID-19) impact on medically assisted reproduction (MAR) services in Europe during the COVID-19 pandemic (March to May 2020)?
SUMMARY ANSWER
...MAR services, and hence treatments for infertile couples, were stopped in most European countries for a mean of 7 weeks.
WHAT IS KNOWN ALREADY
With the outbreak of COVID-19 in Europe, non-urgent medical care was reduced by local authorities to preserve health resources and maintain social distancing. Furthermore, ESHRE and other societies recommended to postpone ART pregnancies as of 14 March 2020.
STUDY DESIGN, SIZE, DURATION
A structured questionnaire was distributed in April among the ESHRE Committee of National Representatives, followed by further information collection through email.
PARTICIPANTS/MATERIALS, SETTING, METHODS
The information was collected through the questionnaire and afterwards summarised and aligned with data from the European Centre for Disease Control on the number of COVID-19 cases per country.
MAIN RESULTS AND THE ROLE OF CHANCE
By aligning the data for each country with respective epidemiological data, we show a large variation in the time and the phase in the epidemic in the curve when MAR/ART treatments were suspended and restarted. Similarly, the duration of interruption varied. Fertility preservation treatments and patient supportive care for patients remained available during the pandemic.
LARGE SCALE DATA
N/A
LIMITATIONS, REASONS FOR CAUTION
Data collection was prone to misinterpretation of the questions and replies, and required further follow-up to check the accuracy. Some representatives reported that they, themselves, were not always aware of the situation throughout the country or reported difficulties with providing single generalised replies, for instance when there were regional differences within their country.
WIDER IMPLICATIONS OF THE FINDINGS
The current article provides a basis for further research of the different strategies developed in response to the COVID-19 crisis. Such conclusions will be invaluable for health authorities and healthcare professionals with respect to future similar situations.
STUDY FUNDING/COMPETING INTEREST(S)
There was no funding for the study, apart from technical support from ESHRE. The authors had no COI to disclose.
We demonstrate how the pitchfork, transcritical and saddle-node bifurcations of steady states observed in dynamical systems with a finite number of isolated equilibrium points occur in systems with ...lines of equilibria. The exploration is carried out by using the numerical simulation and linear stability analysis applied to a model of a memristor-based oscillator. First, all the discussed bifurcation scenarios are considered in the context of systems including Chua's memristor with a piecewise-smooth characteristic. Then the memristor characteristic is changed to a function that is smooth everywhere. Finally, the action of the memristor forgetting effect is taken into consideration. The presented results are obtained for electronic circuit models, but the considered bifurcation phenomena can be exhibited by systems with a line of equilibria of any nature.
For a network of generic oscillators with nonlocal topology and symmetry-breaking coupling we establish novel partially coherent inhomogeneous spatial patterns, which combine the features of chimera ...states (coexisting incongruous coherent and incoherent domains) and oscillation death (oscillation suppression), which we call "chimera death". We show that due to the interplay of nonlocality and breaking of rotational symmetry by the coupling, two distinct scenarios from oscillatory behavior to a stationary state regime are possible: a transition from an amplitude chimera to chimera death via in-phase synchronized oscillations and a direct abrupt transition for larger coupling strength.
Amyotrophic lateral sclerosis is a fatal neurodegenerative disease characterized by progressive muscle wasting, breathing and swallowing difficulties resulting in patient's death in two to five years ...after disease onset. In amyotrophic lateral sclerosis, both upper and lower motor neurons of the corticospinal tracts are involved in the process of neurodegeneration, accounting for great clinical heterogeneity of the disease. Clinical phenotype has great impact on the pattern and rate of amyotrophic lateral sclerosis progression and overall survival prognosis. Creating more homogenous patient groups in order to study the effects of drug agents on specific manifestations of the disease is a challenging issue in amyotrophic lateral sclerosis clinical trials. Since amyotrophic lateral sclerosis has low incidence rates, conduction of multicenter trials requires certain standardized approaches to disease diagnosis and staging. This review focuses on the current approaches in amyotrophic lateral sclerosis classification and staging system based on clinical examination and additional instrumental methods, highlighting the role of upper and lower motor neuron involvement in different phenotypes of the disease. We demonstrate that both clinical and instrumental findings can be useful in evaluating severity of upper motor neuron and lower motor neuron involvement and predicting the following course of the disease. Addressing disease heterogeneity in amyotrophic lateral sclerosis clinical trials could lead to study designs that will assess drug efficacy in specific patient groups, based on the disease pathophysiology and spatiotemporal pattern. Although clinical evaluation can be a sufficient screening method for dividing amyotrophic lateral sclerosis patients into clinical subgroups, we provide proof that instrumental studies could provide valuable insights in the disease pathology.
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