unsolved problem
Recently Published Documents





2022 ◽  
Vol 20 (8) ◽  
pp. 3084
T. V. Umpeleva ◽  
D. V. Vakhrusheva ◽  
S. N. Skornyakov

Conducting fundamental and clinical research in the field of tuberculosis is an important step towards reducing related morbidity and mortality, but access to a sufficient number of high-quality samples required for research is an unsolved problem in Russia. This review is devoted to biobanking as a key component of modern research in personalized medicine, as well as to the status and prospects for developing this area in phthisiology and infectious diseases combined with tuberculosis.

2022 ◽  
Vol 2022 ◽  
pp. 1-15
Zeeshan Saleem Mufti ◽  
Rukhshanda Anjum ◽  
Ayesha Abbas ◽  
Shahbaz Ali ◽  
Muhammad Afzal ◽  

Topological indices are such numbers or set of numbers that describe topology of structures. Nearly 400 topological indices are calculated so far. The prognostication of physical, chemical, and biological attributes of organic compounds is an important and still unsolved problem of computational chemistry. Topological index is the tool to predict the physicochemical properties such as boiling point, melting point, density, viscosity, and polarity of organic compounds. In this study, some degree-based molecular descriptors of hydrocarbon structure are calculated.

2022 ◽  
Vol 2161 (1) ◽  
pp. 012035
Nemika Tyagi ◽  
Sudeshna Chakraborty ◽  
Jyotsna ◽  
Aditya Kumar ◽  
Nzanzu Katasohire Romeo

Abstract Word Sense Disambiguation (WSD) arises due to the presence of ambiguity in the text during the semantic analysis of natural languages. It is a major unsolved problem in the area of Natural Language Processing (NLP) and its applications. This paper explores and reviews WSD algorithms that have contributed to, or created state-of-art solutions in recent years. Moreover, this paper also aims to analyze the recent technological trends in the domain of WSD which can give us leverage to identify the possible future trajectory of the search for better WSD solutions.

2021 ◽  
pp. 088532822110644
Ângela Semitela ◽  
Andreia Leal Pereira ◽  
Cátia Sousa ◽  
Alexandrina F. Mendes ◽  
Paula A.A.P. Marques ◽  

Articular cartilage was expected to be one of the first tissues to be successfully engineered, but replicating the complex fibril architecture and the cellular distribution of the native cartilage has proven difficult. While electrospinning has been widely used to reproduce the depth-dependent fibre architecture in 3D scaffolds, the chondrocyte-controlled distribution remains an unsolved problem. To incorporate cells homogeneously through the depth of scaffolds, a combination of polymer electrospinning and cell seeding is necessary. A multi-layer approach alternating between polymer electrospinning with chondrocyte electrospraying can be a solution. Still, the success of this process is related to the survival rate of the electrosprayed chondrocytes embedded within the electrospun mesh. In this regard, the present study investigated the impact of the multi-layered process and the supplementation of the electrospray chondrocyte suspension with different concentrations of Gelatin and Alginate on the viability of electrosprayed chondrocytes embedded within a Polycaprolactone/Gelatin electrospun mesh and on the mechanical properties of the resulting meshes. The addition of Gelatin in the chondrocyte suspension did not increase significantly ( p > 0.05) the percentage of viable electrosprayed chondrocytes (25%), while 3 wt% Alginate addition led to a significant ( p < 0.05) increase in chondrocyte viability (50%) relative to the case without polymer supplement (15%). Furthermore, the addition of both polymer supplements increased the mechanical properties of the multi-layer construct. These findings imply that this multi-layered approach can be applied to cartilage TE allowing for automated chondrocyte integration during scaffolds creation.

Tatiana Kushch ◽  

ntroduction. This article discusses the “reliquary diplomacy” introduced by Emperor Manuel II Palaiologos during the Ottoman siege of Constantinople (1394–1402). The emperor widely used the relics in the creation of the anti-Ottoman alliance. This article addresses a specific case of this diplomatic practice, Manuel II Palaiologos’ request to Venice for a loan for the deposit on the Tunic of Christ and other relics. Methods. From the juxtaposition of sources and the comparative analysis of the fourteenth-century relations between Byzantium and Venice there are good reasons to discover the motives behind the Venetians’ denial of the emperors’ proposal. Analysis. After 1261 Constantinople kept numerous relics, particularly the Seamless Tunic of Christ and the Purple Robe. The sources in possession do not allow an unequivocal conclusion if the artifact offered to the Venetians was the Seamless Tunic or another one. In the author’s interpretation, the reason of Venice’s withdrawal from the deal was the empire’s bad “credit history.” In August 1343, the Senate of Venice gave credit of 30,000 gold ducats to the Empress Anna of Savoy for the deposit of the jewels of the crown. The Venetians permanently reminded Byzantium about the repayment of the debt and the ransom for the jewels, and, moreover, offered to take the island of Tenedos as a compensation. Therefore, the unsolved problem of the old debt made the new deal with the emperor hopeless in the Venetians’ eyes. Results. The case under analysis sheds light on the state of the Empire in the late fourteenth century. Manuel II Palaiologos put into the “diplomatic circulation” the relics which were convertible in the Christian West. The failure of his negotiations with Venice turned him to active search for other allies, whom he sent parts of the Tunic of Christ in order to gain their military and financial support.

Politeja ◽  
2021 ◽  
Vol 18 (6(75)) ◽  
pp. 159-182
Joanna Mormul

Hijos de las nubes and 45 Years of Dreams: Saharawi Refugees in Algeria Over the years, the issue of the protracted exile of the Saharawi people in Algeria as a consequence of the so far unresolved conflict over the Western Sahara has become a highly politicized problem. The protracted standstill and the lack of clear prospects for a referendum that would ultimately end the conflict make it questionable that the Sahrawi refugee situation will change quickly. The article attempts to analyse the status of the Sahrawi people, taking into account the uniqueness of the Sahrawi refugee camps in Algeria and their importance for the still unsolved problem of Western Sahara. It is based largely on qualitative data collected from fieldwork in Algeria (including Sahrawi refugee camps), Mauritania and Morocco, and the Rabat-controlled territory of Western Sahara, as well as interviews and conversations with representatives of Spanish NGOs involved in helping Sahrawi refugees, Sahrawi living or temporarily staying in Spain and researchers working at Spanish universities.

2021 ◽  
Bhuvanesh Sridharan ◽  
Sarvesh Mehta ◽  
Yashaswi Pathak ◽  
U. Deva Priyakumar

Spectroscopy is the study of how matter interacts with electromagnetic radiations of specific frequencies that has led to several monumental discoveries in science. The spectra of any particular molecule is highly information-rich, yet the inverse relation from the spectra to the molecular structure is still an unsolved problem. Nuclear Magnetic Resonance (NMR) spectroscopy is one such critical tool in the tool-set for scientists to characterise any chemical sample. In this work, a novel framework is proposed that attempts to solve this inverse problem by navigating the chemical space to find the correct structure that resulted in the target spectra. The proposed framework uses a combination of online Monte- Carlo-Tree-Search (MCTS) and a set of offline trained Graph Convolution Networks to build a molecule iteratively from scratch. Our method is able to predict the correct structure of the molecule ∼80% of the time in its top 3 guesses. We believe that the proposed framework is a significant step in solving the inverse design problem of NMR spectra to molecule.

2021 ◽  
Vol 29 (1) ◽  
pp. 137-149
Aleksandr M. Batkovskiy ◽  
Pavel V. Kravchuk ◽  
Evgenii Iu. Khrustalev

The currently used methods of optimizing the management of diversification activities are insufficiently theoretically substantiated. The available tools for this optimization do not allow quantitatively taking into account many factors affecting this process in today's difficult economic conditions, which gives rise to many problems. Among them, an important and still unsolved problem is a scientifically grounded quantitative assessment of risks for the implementation of diversification measures. It is especially relevant now for the enterprises of the military-industrial complex. The authors propose an approach to the study of the theoretical foundations of optimization of production diversification management as a form of systemic transformation of enterprises and a new toolkit for solving the problem under consideration based on the use of the expert assessment method and economic and mathematical modeling of risk analysis of diversification measures. Significance of the research is determined by the need to optimize the management of production diversification at the enterprises of the military-industrial complex.

2021 ◽  
Frank Vega

The Riemann hypothesis has been considered the most important unsolved problem in mathematics. Robin criterion states that the Riemann hypothesis is true if and only if the inequality $\sigma(n) < e^{\gamma } \times n \times \log \log n$ holds for all natural numbers $n > 5040$, where $\sigma(n)$ is the sum-of-divisors function of $n$ and $\gamma \approx 0.57721$ is the Euler-Mascheroni constant. We show that the Robin inequality is true for all natural numbers $n > 5040$ which are not divisible by the prime $3$. Moreover, we prove that the Robin inequality is true for all natural numbers $n > 5040$ which are divisible by the prime $3$. Consequently, the Robin inequality is true for all natural numbers $n > 5040$ and thus, the Riemann hypothesis is true.

Wei Fan

The wave-particle duality of quantum mechanics has always been an unsolved problem in physics. This article attempts to use one of the properties to explain the other, so as to eliminate the confusion of quantum mechanics probability waves. Specifically, this article finds that the discreteness of energy is the inherent property of all waves, so this article explains the particle nature of light from the perspective of light wave, thereby eliminating the confusion of light’s wave-particle duality; in addition, this article found that microscopic matter particles are only suitable for discussing the number of scattered particles or energy flow density, not their position and momentum, when they are forced to discuss their position and momentum, it will inevitably lead to confusion about probability waves, when only discussing the number of scattered particles or energy flow density, its volatility can be explained from the perspective of particle nature, thereby eliminating the confusion of microscopic matter particle probability waves. When the attribute of light as a wave is established, the light needs to overcome the Hamiltonian of the medium in different constraint systems (gravitational fields) during the propagation process, which will produce a universal redshift phenomenon, this can provide a new understanding of cosmic redshift; when the property of light as a wave is established, it means that the speed of light is a constant speed relative to the medium, which can provide a new understanding of the principle of constant speed of light.

Sign in / Sign up

Export Citation Format

Share Document