bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPATIBILITY SCREENING OF VIDAGLIPTIN WITH IONIC AND NON-IONIC POLYMERIC EXCIPIENTS FOR THE DESIGN OF EXTENDED RELEASE DELIVERY SYSTEM
Authors:   Girijananda Chowdhury Institute of Pharmaceutical Science, Azara, Guwahati, (Affiliated to Assam Science and Technology University, Tetelia, Jalukbari, Guwahati), Kamrup, Assam (India)., Saharia Balen , Das Gouranga ,   Girijananda Chowdhury Institute of Pharmaceutical Science, Azara, Guwahati, (Affiliated to Assam Science and Technology University, Tetelia, Jalukbari, Guwahati), Kamrup, Assam (India)., Nath Bipul ,   Royal School of Pharmacy, The Assam Royal Global University, Betkuchi, Guwahati-781035, Kamrup, Assam, India.
Published: May 2021

Studies of drug-polymer compatibility play an important role in the preformulation stage for the development of pharmaceutical dosage forms. The potential physical and chemical interactions between drugs and polymer can affect the chemical nature, stability and bioavailability of the dosage form and as a result in the therapeutic response in the clinical phase. The present study reveals the thermal and spectroscopic study of physical mixtures of Vildagliptin (VDG) and HPMC in combination with cationic polymers chitosan, anionic polymers NaCMC and nonionic polymers PEO for extended release (ER). In the first phase of the study, differential scanning calorimeter (DSC) was used as tool to detect any interaction. In the next phase, a Fourier Transform Infrared Spectroscopy (FT-IR) technique was used to confirm and to investigate the type of the possible interactions between the components. In both cases, the spectroscopic data revealed that the analysed polymeric excipients did not show any affect on the VDG. Results of the present study indicated the suitability of the HPMC K4M hydrophilic matrix polymers in combination with cationic polymers, anionic polymers and non-ionic polymers in the preparation of extended release formulation of VDG.
A COMPREHENSIVE REVIEW ON EVALUATION OF ENVIRONMENTAL FRIENDLY MACHINABILITY, CUTTING FLUIDS AND TECHNIQUES IN METAL CUTTING OPERATION
Authors:   School Of Manufacturing Skills, Bhartiya Skill Development University, Jaipur 302037, India., Sharma Rajeev , Kumar Jha Binit ,   School Of Manufacturing Skills, Bhartiya Skill Development University, Jaipur 302037, India., Pahuja Vipin ,   School Of Manufacturing Skills, Bhartiya Skill Development University, Jaipur 302037, India.
Published: May 2021

Todays, due to the environmental concerns, growing contamination and pollution regulations, the demand for renewable and biodegradable cutting fluids is increasing day by day. Environmental friendly machining is one of the latest approach which is economical and also eco-friendly that improve the machinability. Different types of environmental friendly machining techniques are available e.g. MQL machining, cryogenic machining, dry machining and high pressure cooling approach. In this article, an attempt is made regarding environmental friendly machining processing, including different types of cutting fluids and machining techniques. The Knowledge of cutting fluid and its processing conditions is of critically importance to maximize the efficiency of cutting fluids in any machining process. In general, the generation of heat in the cutting zone due to friction at the tool-chip interface and the friction between the safety surface of the tool and the work piece is always the deciding factor on the quality of the work piece surface. In any manufacturing industries or company two factors play important role in machinability and productivity e.g. surface quality and tool wear. The main objective of this review article that analysis the different environmental friendly machining techniques and encourages the cooling approach in metal cutting operation. So finally, after the literature survey found that environmental friendly machining approach is cost effective machining process and also eco-friendly machining process.
Stability analysis of mechanical systems with distributed delay via decomposition
Authors:   St. Petersburg State University, Aleksandrov Alexander Yu. , Tikhonov Alexey A. ,   St. Petersburg State University
Published: May 2021

The article analyzes a linear mechanical system with a large parameter at the vector of velocity forces and a distributed delay in positional forces. With the aid of the decomposition method, conditions are obtained under which the problem of stability analysis of the original system of the second-order differential equations can be reduced to studying the stability of two auxiliary first-order subsystems. It should be noted that one of the auxiliary subsystems does not contain a delay, whereas for the second subsystem containing a distributed delay, the stability conditions are formulated in terms of the feasibility of systems of linear matrix inequalities. To substantiate this decomposition, the Lyapunov direct method is used. Special constructions of Lyapunov—Krasovskii functionals are proposed. The developed approach is applied to the problem of monoaxial stabilization of a rigid body. The results of a numerical simulation are presented confirming the conclusions obtained analytically.
Estimates in the Taylor series method for polynomial total systems of PDEs
Authors:   St. Petersburg State University, Babadzanjanz Levon K. , Pototskaya Irina Yu. ,   St. Petersburg State University, Pupysheva Yulia Yu. ,   St. Petersburg State University
Published: May 2021

Many of total systems of PDEs can be reduced to the polynomial form. As was shown by various authors, one of the best methods for the numerical solution of the initial value problem for ODE systems is the Taylor Series Method (TSM). In the article, the authors consider the Cauchy problem for the total polynomial PDE system, obtain the recurrence formulas for Taylor coefficients, and then formulate and prove a theorem on the accuracy of its solutions by TSM.
Non-linear optimization for continuous travel demand estimation
Authors:   St. Petersburg State University, Raevskaya Anastasiya P. , Krylatov Alexander Y. ,   St. Petersburg State University
Published: May 2021

Models and methods of traffic distribution are being developed by researchers all over the world. The development of this scientific field contributes to both theory and practice. In this article, the non-linear optimization of traffic flow re-assignment is examined in order to solve continuously the travel demand estimation problem. An approach has been developed in the form of computational methodology to cope with the network optimization problem. A uniqueness theorem is proved for a certain type of road network. Explicit relations between travel demand and traffic flow are obtained for a single-commodity network of non-intersecting routes with special polynomial travel time functions. The obtained findings contribute to the theory and provide a fresh perspective on the problem for transportation engineers.
The codifferential descent method in the problem of finding the global minimum of a piecewise affine objective functional in linear control systems
Authors:   St. Petersburg State University, Fominyh Alexander V. , Karelin Vladimir V. ,   St. Petersburg State University, Polyakova Lyudmila N. ,   St. Petersburg State University, Myshkov Stanislav K. ,   St. Petersburg State University, Tregubov Vladimir P. ,   St. Petersburg State University
Published: May 2021

The article considers the problem of optimal control of an object described by a linear nonstationary system and with a piecewise affine quality functional. The problem is examined in Mayer’s form with both free and partially fixed right endpoints. Piecewise continuous and bounded controls that lie in some parallelepiped at each moment of time are admissible. The standard discretization of the original system and the control parametrization are used, some convergence theorems of the discrete problem solution to the continuous problem solution are presented. Further, for the obtained discrete system, the necessary and sufficient minimum conditions are written out in terms of the codifferential, the method of the modified codifferential descent is applied to it, which guarantees to find the global minimum of this problem in a finite number of steps. The proposed algorithm is illustrated with examples.
Conceptual model of a data transmission network for a polymodal control system in critical state infrastructure
Authors:   Information Technologies, Mechanics and Optics University, Saitov Sergey I. , Budkov Viktor Yu. ,   St. Petersburg Federal Research Center of the Russian Academy of Sciences, Levonevsky Dmitrii K. ,   St. Petersburg Federal Research Center of the Russian Academy of Sciences, Denisov Alexandr V. ,   St. Petersburg Federal Research Center of the Russian Academy of Sciences
Published: May 2021

Approaches to modeling a data transmission network in a remotely controlled system for distributed critical state facilities are considered in the article. To solve the problem of increasing the efficiency of channel resource costs, a new analytical model of the information distribution system from the standpoint of teletraffic theory is proposed. The model describes the service of extraordinary calls with absolute priorities, failures and gradient reservation of the channel resource for messages of modalities with the characteristics of operators in the data transmission network of critical facilities.
Draft of the Third National Standard of Russia for Fast Automatic Learning of Large Correlation Neural Networks on Small Training Samples of Biometric Data
Authors:   Federal State Government-financed Estamblishment Penza State University, Ivanov Alexander ,   JSC “Penza Research Electrotechnical Institute”, Sulavko Alexeiy ,   Omsk State Technical University
Published: May 2021

The aim of the study is to show that a biometrics-to-access code converter based on large networks of correlation neurons makes it possible to obtain an even longer key at the output while ensuring the protection of biometric data from compromise. The research method is the use of large «wide» neural networks with automatic learning for the implementation of the biometric authentication procedure, ensuring the protection of biometric personal data from compromise. Results of the study - the first national standard GOST R 52633.5 for the automatic training of neuron networks was focused only on a physically secure, trusted computing environment. The protection of the parameters of the trained neural network converters biometrics-code using cryptographic methods led to the need to use short keys and passwords for biometric-cryptographic authentication. It is proposed to build special correlation neurons in the meta-space of Bayes-Minkowski features of a higher dimension. An experiment was carried out to verify the patterns of kkeystroke dynamics using a biometrics-to-code converter based on the data set of the AIConstructor project. In the meta-space of features, the probability of a verification error turned out to be less (EER = 0.0823) than in the original space of features (EER = 0.0864), while in the protected execution mode of the biometrics-to-code converter, the key length can be increased by more than 19 times. Experiments have shown that the transition to the mat space of BayesMinkowski features does not lead to the manifestation of the “curse of dimension” problem if some of the original features have a noticeable or strong mutual correlation. The problem of ensuring the confidentiality of the parameters of trained neural network containers, from which the neural network converter biometrics-code is formed, is relevant not only for biometric authentication tasks. It seems possible to develop a standard for protecting artificial intelligence based on automatically trained networks of Bayesian-Minkowski correlation neurons.
Sualtı Kültür Mirası Araştırmaları Hakkında Bibliyometrik Bir Analiz
Authors: Ertek Şimal , Şahin Mehmet Tahsin
Published: May 2021

Arkeolojik miras, insanlık tarihindeki etkileşimlerin belgeleri olarak görülmektedir. Bu belgelerin ortaya çıkarılıp araştırılması, korunması ve doğru bir biçimde yönetilmesi gerekmektedir. Sualtı kültür mirasının korunması ve anlaşılması, iklim, deniz seviyesi ve kültürel değişimlerin anlaşılmasını aynı zamanda gelecek nesillere aktarılmasını sağlamaktadır. Bu sebeple Sualtı Kültür Mirası alanında yapılan çalışmalar önem arz etmektedir. Yapılan literatür taramaları sonucunda Sualtı Kültür Mirası Araştırmaları konusunda herhangi bir bibliyometrik analiz çalışmasına rastlanılmamaktadır. Bu bakımdan bu çalışma önem arz etmektedir. Bu araştırmada, Sualtı Kültür Mirası Araştırmaları hakkında yayınlanmış olan araştırmalar incelenmektedir. Veritabanı olarak Taylor and Francis, ScienceDirect, Web of Science, DergiPark, Sobiad, Tr Dizin (Ulakbim) seçilmiştir. Tüm veritabanlarında yapılan taramalar sonucunda 1976-2020 yılları arasında çalışılmış olan 250 makale incelemeye alınmıştır. Makaleler incelenirken nitel araştırma yöntemlerinden bibliyometrik analiz tekniği kullanılmıştır. Araştırma kapsamındaki makaleler belirlenen kategorilerde sayısallaştırılıp grafiklere dönüştürülerek yorumlanmıştır.
Medial compartment disease bij een jonge grote münsterländer
Authors: Coppieters E. , Samoy Y. , Pey P. , Waelbers T. , Van Ryssen B.
Published: May 2021

Medial Compartment Disease (MCD) is een recentelijk herkende aandoening van de elleboog bij de hond en verwijst naar uitgebreide kraakbeenerosie in het mediaal gedeelte van het ellebooggewricht. Deze casuïstiek beschrijft een geval van MCD bij een grote münsterländer van tien maanden oud, aangeboden met de klacht van manken op de rechtervoorpoot. Op basis van het signalement, de anamnese en het radiografisch onderzoek was er een sterk vermoeden van een losse processus coronoïdeus van de rechterelleboog. Artroscopische inspectie van het gewricht bracht naast een klein coronoïdfragment en een klein osteochondrotisch letsel echter ook uitgebreide kraakbeenerosie van de mediale humeruscondyl en de mediale processus coronoïdeus aan het licht. Na de artroscopische behandeling vertoonde de hond geen beterschap. Een behandeling met autoloog geconditioneerd plasma (Arthrex- ACP®) gaf evenmin substantiële verbetering. Uiteindelijk werd de hond geëuthanaseerd omwille van aanhoudend manken.
Schmallenbergvirus: het opduiken van een Orthobunyavirus bij herkauwers in West-Europa
Authors: Steukers L. , Bertels G. , Cay A. B. , Nauwynck H. J.
Published: May 2021

Recent werd er een nieuw virus geïdentificeerd bij herkauwers in West-Europa. Dit virus, het Schmallenbergvirus, behoort tot de familie Bunyaviridae, genus Orthobunyavirus, serogroep Simbu en vertoont sterke verwantschap met het Akabane-, Aino- en Shamondavirus. Bij runderen bestaan de acute symptomen bij het moederdier en volwassen dieren in het algemeen uit onder andere hoge koorts, milk drop en diarree. Opmerkelijk is het effect van het virus op de foetus. Infectie tijdens de dracht kan aanleiding geven tot abortus, doodgeboorte en ernstige congenitale malformaties. Net zoals alle andere bunyavirussen wordt Schmallenbergvirus overgedragen door vectoren. Gelijkaardige virussen, zoals Akabane en Akabane-achtige virussen, worden op die manier overgedragen door Culicoides. Vermoedelijk zijn ook gelijkaardige vectoren van belang voor de transmissie van Schmallenbergvirus. Deze review geeft een overzicht van Bunyaviridae, hun epidemiologie, symptomen, preventie en bestrijding. Speciale aandacht gaat hierbij naar gelijkenissen tussen het Schmallenbergvirus en andere leden van de Simbu-serogroep.
Partusinductie bij de zeug
Authors: Decaluwe R. , Janssens G. P. J. , Declerck I. , de Kruif A. , Maes D.
Published: May 2021

Partusinductie verhoogt het toezicht tijdens het werpen, waardoor het geboortegetal kan toenemen. Wanneer partusinductie echter niet correct wordt toegepast, kan dit leiden tot vroeggeboorte. Daarom mag partusinductie pas ten vroegste twee dagen vóór de gemiddelde drachtduur van de zeugen op een bedrijf worden uitgevoerd. Voor partusinductie bestaan verschillende protocols, zoals de eenmalige toediening van prostaglandinen, de dubbele toediening van prostaglandinen met zes uur interval (split-dose-techniek) en de combinatie van prostaglandinen met oxytocine 24 uur later en verschillende toedieningswegen, zoals intramusculaire injectie in de nekregio en injectie in de buurt van de vulva. Andere strategieën bestaan maar zijn minder effectief en/of worden minder frequent gebruikt. Na een eenmalige injectie van prostaglandinen werpt 60% van de zeugen binnen de werkuren (22-32 uur na injectie). Met de split-dose-techniek of de combinatie van prostaglandinen en oxytocine 24 uur later is dit 80%. Bij incorrect gebruik is oxytocine echter een risicofactor voor asfyxie bij biggen. Het wel of niet toepassen van partusinductie en welk protocol het beste wordt gebruikt hangen af van het bedrijf en de wensen van de veehouder.
Hemipelvectomie bij de hond: een patiëntenstudie van drie honden
Authors: Van Hautegem L. , Van Goethem B. , Cornelis I. , Toom M. , De Rooster H.
Published: May 2021

Hemipelvectomie omvat het chirurgisch verwijderen van een deel van het bekken. Deze ingreep wordt uitgevoerd wanneer er een maligne tumor aanwezig is. Omwille van de bezorgdheden omtrent invasiviteit wordt deze ingreep zelden uitgevoerd. De voorbije tien jaar ondergingen drie honden hemipelvectomie in de Universitaire Kliniek Kleine Huisdieren van de Faculteit Diergeneeskunde (UGent): totale hemipelvectomie gecombineerd met pootamputatie bij twee honden en mid-caudale partiële hemipelvectomie gecombineerd met pootamputatie bij één hond. De reden voor de ingreep was een perifere zenuwschedetumor (PNST) bij twee honden en een primaire bottumor (OSA) bij één hond. Perioperatieve complicaties bestonden uit bloedverlies, hypothermie, hematurie en oligurie. Postoperatieve ondersteuning was nodig gedurende een vijftal dagen. Bij één patiënt volgde een bijkomende ingreep aangezien de resectieranden niet tumor-vrij bleken te zijn. De honden waren ambulant en hadden een goede levenskwaliteit. De mediane overlevingstijd bedroeg 578 dagen (PNST 594 dagen en OSA 533 dagen). De twee honden met PNST werden geëuthanaseerd wegens lokale teruggroei van de tumor en de hond met OSA wegens pulmonaire metastasen.
Влияние барьерных контактов на транспорт носителей заряда в однородных структурах из GaAs, легированных глубокими центрами Cr и EL2
Authors: Верхолетов М.Г. , Прудаев И.А.
Published: May 2021

The results of studying the transport of charge carriers in GaAs structures doped with deep donor EL2 centers and acceptor levels of Cr for detectors of ionizing radiation and ultrafast photoelectric switches are presented. Three configurations of structures are investigated: p-i-n, n-i-n and p-i-p- types. The system of differential equations for the temperature of charge carriers, Poisson's equations and continuity was solved using a commercial software. It was found that the choice of the type of the barrier layer makes it possible to control the uniformity of the electric field strength in the structures. It is shown that p-i-p- type structures have the best uniformity of the electric field strength.
Wearable Bioimpedance Monitoring: Viewpoint for Application in Chronic Conditions
Authors: Groenendaal Willemijn , Lee Seulki , van Hoof Chris
Published: May 2021

Currently, nearly 6 in 10 US adults are suffering from at least one chronic condition. Wearable technology could help in controlling the health care costs by remote monitoring and early detection of disease worsening. However, in recent years, there have been disappointments in wearable technology with respect to reliability, lack of feedback, or lack of user comfort. One of the promising sensor techniques for wearable monitoring of chronic disease is bioimpedance, which is a noninvasive, versatile sensing method that can be applied in different ways to extract a wide range of health care parameters. Due to the changes in impedance caused by either breathing or blood flow, time-varying signals such as respiration and cardiac output can be obtained with bioimpedance. A second application area is related to body composition and fluid status (eg, pulmonary congestion monitoring in patients with heart failure). Finally, bioimpedance can be used for continuous and real-time imaging (eg, during mechanical ventilation). In this viewpoint, we evaluate the use of wearable bioimpedance monitoring for application in chronic conditions, focusing on the current status, recent improvements, and challenges that still need to be tackled.
Incorporating Medical Students Into Primary Care Telehealth Visits: Tutorial
Authors: Balaji Aanika , Clever Sarah Lou
Published: May 2021

Background

The COVID-19 pandemic has brought about sweeping change in health care delivery, which has shifted from in-person consultations to a web-based format. Few medical schools provide web-based medicine or telemedicine training to their learners, though this is likely to be important for future medical practice.

Objective

This tutorial communicates a framework for incorporating medical students into primary care telemedicine clinics.

Methods

A third-year medical student and internal medicine attending physician from the Johns Hopkins University completed telemedicine clinic visits in April 2020 by using a variety of video platforms and via telephone calls.

Results

Nine telemedicine visits were completed over 4 clinic days. Our patients were, on average, aged 68 years. The majority of patients were female (6/9, 67%), and most appointments were completed via a video platform (6/9, 67%). Additionally, our experience is summarized and describe (1) practical tips for how to prepare for a telehealth visit; (2) technology considerations; (3) recommendations for participation during a telehealth visit; (4) debriefing and feedback; (5) challenges to care; and (6) student, care provider, and patient reactions to telemedicine visits.

Conclusions

Telemedicine clinics have been successfully used for managing patients with chronic conditions, those who have attended low-risk urgent care visits, and those with mental health concerns. Patients have reported high patient satisfaction scores for telemedicine visits, and the majority of patients are comfortable with having medical students as part of their care team. Moving forward, telemedicine will remain a popular method for receiving health care. This study has highlighted that medical students can successfully be integrated into telemedicine clinics and that they should be exposed to telehealth whenever possible prior to residency.
Evidence of Human-Level Bonds Established With a Digital Conversational Agent: Cross-sectional, Retrospective Observational Study
Authors: Darcy Alison , Daniels Jade , Salinger David , Wicks Paul , Robinson Athena
Published: May 2021

Background

There are far more patients in mental distress than there is time available for mental health professionals to support them. Although digital tools may help mitigate this issue, critics have suggested that technological solutions that lack human empathy will prevent a bond or therapeutic alliance from being formed, thereby narrowing these solutions’ efficacy.

Objective

We aimed to investigate whether users of a cognitive behavioral therapy (CBT)–based conversational agent would report therapeutic bond levels that are similar to those in literature about other CBT modalities, including face-to-face therapy, group CBT, and other digital interventions that do not use a conversational agent.

Methods

A cross-sectional, retrospective study design was used to analyze aggregate, deidentified data from adult users who self-referred to a CBT-based, fully automated conversational agent (Woebot) between November 2019 and August 2020. Working alliance was measured with the Working Alliance Inventory-Short Revised (WAI-SR), and depression symptom status was assessed by using the 2-item Patient Health Questionnaire (PHQ-2). All measures were administered by the conversational agent in the mobile app. WAI-SR scores were compared to those in scientific literature abstracted from recent reviews.

Results

Data from 36,070 Woebot users were included in the analysis. Participants ranged in age from 18 to 78 years, and 57.48% (20,734/36,070) of participants reported that they were female. The mean PHQ-2 score was 3.03 (SD 1.79), and 54.67% (19,719/36,070) of users scored over the cutoff score of 3 for depression screening. Within 5 days of initial app use, the mean WAI-SR score was 3.36 (SD 0.8) and the mean bond subscale score was 3.8 (SD 1.0), which was comparable to those in recent studies from the literature on traditional, outpatient, individual CBT and group CBT (mean bond subscale scores of 4 and 3.8, respectively). PHQ-2 scores at baseline weakly correlated with bond scores (r=−0.04; P<.001); however, users with depression and those without depression had high bond scores of 3.45.

Conclusions

Although bonds are often presumed to be the exclusive domain of human therapeutic relationships, our findings challenge the notion that digital therapeutics are incapable of establishing a therapeutic bond with users. Future research might investigate the role of bonds as mediators of clinical outcomes, since boosting the engagement and efficacy of digital therapeutics could have major public health benefits.
Evidence of Human-Level Bonds Established With a Digital Conversational Agent: Cross-sectional, Retrospective Observational Study (Preprint)
Authors: Darcy Alison , Daniels Jade , Salinger David , Wicks Paul , Robinson Athena
Published: May 2021

BACKGROUND

There are far more patients in mental distress than there is time available for mental health professionals to support them. Although digital tools may help mitigate this issue, critics have suggested that technological solutions that lack human empathy will prevent a bond or therapeutic alliance from being formed, thereby narrowing these solutions’ efficacy.

OBJECTIVE

We aimed to investigate whether users of a cognitive behavioral therapy (CBT)–based conversational agent would report therapeutic bond levels that are similar to those in literature about other CBT modalities, including face-to-face therapy, group CBT, and other digital interventions that do not use a conversational agent.

METHODS

A cross-sectional, retrospective study design was used to analyze aggregate, deidentified data from adult users who self-referred to a CBT-based, fully automated conversational agent (Woebot) between November 2019 and August 2020. Working alliance was measured with the Working Alliance Inventory-Short Revised (WAI-SR), and depression symptom status was assessed by using the 2-item Patient Health Questionnaire (PHQ-2). All measures were administered by the conversational agent in the mobile app. WAI-SR scores were compared to those in scientific literature abstracted from recent reviews.

RESULTS

Data from 36,070 Woebot users were included in the analysis. Participants ranged in age from 18 to 78 years, and 57.48% (20,734/36,070) of participants reported that they were female. The mean PHQ-2 score was 3.03 (SD 1.79), and 54.67% (19,719/36,070) of users scored over the cutoff score of 3 for depression screening. Within 5 days of initial app use, the mean WAI-SR score was 3.36 (SD 0.8) and the mean bond subscale score was 3.8 (SD 1.0), which was comparable to those in recent studies from the literature on traditional, outpatient, individual CBT and group CBT (mean bond subscale scores of 4 and 3.8, respectively). PHQ-2 scores at baseline weakly correlated with bond scores (r=−0.04; P<.001); however, users with depression and those without depression had high bond scores of 3.45.

CONCLUSIONS

Although bonds are often presumed to be the exclusive domain of human therapeutic relationships, our findings challenge the notion that digital therapeutics are incapable of establishing a therapeutic bond with users. Future research might investigate the role of bonds as mediators of clinical outcomes, since boosting the engagement and efficacy of digital therapeutics could have major public health benefits.
ARE COSTS STICKY? EVIDENCE FROM SERBIA
Authors: Jugović Jovana
Published: May 2021

This paper is focused on the theory of sticky costs, created out of researches which pointed to the fact that costs do not act symmetrically in the case of equivalent increase and decrease of the activity volume, as it is implied by the traditional cost theory. Deliberate business decisions, the ones made in order to increase company’s value, as well as opportunistic decisions aimed at the realization of managers' personal goals are found as some of essential causes of cost stickiness. In order to examine the phenomenon of stickiness in the cost behavior of companies that operate in Serbia, we conducted a research on a sample of 917 medium and large companies from manufacturing sector for the period 2007 – 2016. The analysis of panel data pointed to the presence of stickiness in the behavior of operating costs - it showed that they grow by 0.847% as revenues grow by 1%, and they fall by 0.718 % due to 1% drop in revenues. We also found a lagged adjustment to operating costs for changes in operating revenues and partial reversal of stickiness in the period after a revenue decrease.
Crisoles y moldes en Los Nogales
Authors: Plaza María Teresa , Pavlovic Daniel , Martinón-Torres Marcos
Published: May 2021

The spread of the Tawantinsuyu in the Aconcagua Valley (Central Chile) is thought to have been culturally mediated, avoiding military coercion, and thus leading to different forms of cultural acceptance, resistance or hybridisation. However, very few studies have discussed how this process is reflected in the metallurgical production during the Late Period (ca. AD 1400-1530). The result of a technological study on a group of crucibles and moulds from Los Nogales (Aconcagua valley), using optical microscopy, petrography, SEM-EDS, XRD and FTIR is presented here. Results indicate that the raw materials used were local igneous rocks obtained from alluvial deposits, mixed with small amounts of smectite-montmorillonite clay. Moulds also contained bone ash as temper. Firing temperatures were estimated between 800-850 ºC for moulds and above 900 ºC for crucibles. Their manufacture technology and morphology indicate that these technical ceramics were made following a technological tradition originated in northwest Argentina that was introduced to the Aconcagua valley during the expansion of the Tawantinsuyu, and accepted by local communities.
De extranjeros a ciudadanos urbanos
Authors: Pérez Miguel , Palma Cristóbal
Published: May 2021

In several metropolises of the so-called Global South, the claim for the right to live in the city has resulted in widespread processes of “autoconstruction”, a concept that alludes to a mode of producing the urban peripheries in which poor residents are the main agents of urbanization. Autoconstruction has made possible the emergence of new forms of citizenship in which the urban poor have generated novel spaces for civic participation through which they have tur-ned into legitimate rights-bearers. What happens, however, when the agents of autoconstruc-tion are immigrants demanding not only the right to housing, but also their recognition as subjects of rights in a nation-state that does not consider them citizens? This article discusses that question by ethnographically examining the case of Nueva Esperanza squatter settlement, an autoconstructed neighborhood in Colina, Santiago in which most of its residents are foreigners. We conclude that, to constitute themselves as citizens, immigrants formulate an “urban” type of citizenship in which the act of residing in the city turn them into rights-bearers. In such a process, these residents build ethical and political narratives through which they make sense of their desires for incorporation and belonging to the national political community.
Satellite detection of the 1982 El Chichon eruptions and stratospheric dust cloud.
Authors: Matson M. , Robock A.
Published: May 2021

Las erupciones del volcán El Chichón del 28 de marzo y del 3 y el 4 de abril de 1982 fueron percibidas y observadas mediante los satélites ambientales geoestacionarios y de órbita polar.Con base en los datos de dichos satélites se concluyó que la erupción del 28 de marzo, la segunda de las dos erupciones del 3 de abril y la del 4 de abril inyectaron materiales terrestres en la estratosfera a alturas entre 17 y 31 km. Se observó en las imágenes de satélite que la nube de polvo estratosférico resultante de la erupción del 4 de abril completó su viaje alrededor de la Tierra en un período de tres semanas. Se pudo determinar que la altitud de la nube de polvo fue aproximadamente de 24 km.
On the effect of the volcanic eruptions of Mount Agung and El Chichón on the temperature of the stratosphere
Authors: Labitzke K. , Naujokat B.
Published: May 2021

Durante el verano y el otoño de 1982, y también durante el verano y el otoño de 1963, la temperatura a 30 mbar subió más de tres desviaciones estándar sobre el promedio de 18 años en latitudes tropicales. Estos calentamientos se atribuyen a los aerosoles estratosféricos producidos por las erupciones del Monte Agung en marzo de 1963 y de El Chichón en abril de 1982.
Lidar Monitoring at mid latitude of the stratospheric aerosol perturbation produced by the El Chichón eruption
Authors: Altorio A. D´ , Visconti G.
Published: May 2021

Reportamos mediciones lidar de la perturbación en la carga de polvo atmosférico producida por la erupción volcánica de El Chichón. Las mediciones abarcan un período de 19 meses y se toman en una estación de latitud media. El análisis de la tasa de dispersión de fondo y la dispersión de fondo integrada como una función de la altitud muestra que hasta fines del verano de 1982, contribuían a la densidad óptica principalmente las capas de elevada altitud (≥ 25 km). Desde el otoño de 1982 la llegada de la nube principal a latitud media formó una sola capa amplia que se extendía de 15 a 30 km. La lenta disminución en la altitud de esta capa, 7 - 8 km en 12 meses, se atribuye en parte a la circulación general y a las velocidades de asentamiento de las partículas de polvo. Se muestra que nuestros datos de densidad óptica son compatibles con otras mediciones similares independientes.
El Chichón cloud over central Europe
Authors: Jager H. , Reiter R. , Carnut W. , Funk W.
Published: May 2021

El transporte hacia el norte del aerosol estratosférico proveniente de la erupción del volcán mexicano El Chichón en abril de 1982 fue observado por lidar en Garmisch-Partenkirchen (RFA). De junio a octubre de 1982 pudieron observarse dos capas, una por debajo y la otra por encima de los 20 km de altura. De octubre en adelante, una capa se extendió desde la tropopausa hasta alrededor de 30 km de altura. La dispersión de fondo máxima a partir de esta capa se registró durante los dos primeros meses de 1983. Posteriormente, el aerosol de El Chichón aparentemente entró en fase de decadencia. La dispersión de fondo observada fue convertida a valores de profundidad óptica y masa de columna, que alcanzaron sus picos en enero de 1983 con 0.2 a 550 mn y 0.06 g m-2, respectivamente. Comparándola con otras erupciones de largo alcance ocurridas desde 1979, la erupción de El Chichón resulta haber excedido a todas ellas en por lo menos un orden de magnitud.
Lidar observations of the El Chichón aerosol at a southern latitude station
Authors: Clemesha B.R. , Simonich D.M
Published: May 2021

Las mediciones por lidar efectuadas en Sao José dos Campos (23°S, 46oW) muéstran que la nube de polvo había alcanzado esta latitud a mediados de julio de 1982. La primera medición efectuada después de la erupción mostraba dos capas con tasas de dispersión de 1.8 y 2. 7 a 18 y 24 km de altitud, respectivamente, al compararlas con los valores de pre-inyección de alrededor de 1.2. Estos valores se refieren a la longitud de onda de 5890 X, y son para un perfil obtenido el 9 de julio. Las mediciones hechas en los meses subsiguientes mostraban fluctuaciones grandes, particularmente en la capa superior, donde la tasa de dispersión variaba entre 1.2 y 5. La capa inferior variaba mucho menos que la superior, con el resultado de que la dispersión de fondo integrada, una medida de la carga de aerosol estratosférico, permaneció aproximadamente constante hasta fnes de agosto, cuando aumentó de alrededor de 3 x 10-4 SR-1 a alrededor de l x 10-3 SR-1 . Posteriormente a esta fecha, el aerosol integrado oscilaba a alrededor de un valor de 8 x 10-4 SR-1 hasta mediados de marzo de 1983, decreciendo desde entonces a alrededor de 5 x 10-4 SR-1 . Con el tiempo, la altura de la capa superior disminuyó de manera bastante uniforme hasta fines de noviembre, cuando alcanzó 20 km;para entonces ya se había mezclado con la capa inferior. En 1983 la capa se mostró de nuevo como una estructura bifurcada con un pico inferior cercano a los 18 km y uno superior de 2 a 4 km más arriba.
Evidence of the El Chichón stratospheric volcanic cloud in Northern Greece
Authors: Zerefos C. S.
Published: May 2021

El borde norte de los residuos del SO2 volcánico lanzado a la estratósfera por El Chichón fue rastreado en Tesalónica (41 ºN) desde principios del verano de 1982. La evidencia se basa en mediciones de rutina del SO2 columnar, hechas con el espectrofotómetro Brewer Mark II fuera de la ciudad de Tesalónica. Tomando en cuenta la contribución de la contaminación troposférica al S02 columnar, se espera que alrededor de 2 m-atm-cm del S02 columnar pueda atribuirse a la carga estratosférica de origen volcánico.
Atmospheric impact of the volcanic eruptions of El Chichon over Mexico
Authors: Galindo I. , Otaola J. A. , Zenteno G.
Published: May 2021

En el presente trabajo reportarnos los efectos observados en la troposfera sobre el territorio mexicano después de las erupciones del volcán Chichón. En el estudio se utilizaron los registros de temperatura del aire de cinco observatorios, así como las observaciones de radiación solar y turbiedad atmosférica realizadas en la Ciudad de México. Los resultados, a partir de los datos observacionales, muestran que de mayo-junio 1982 a marzo-abril 1983 se observó en todos los observatorios una tendencia al enfriamiento de la temperatura en superficie. Al final del enfriamiento, se presentó un calentamiento abrupto en el verano de 1983 concomitante a una extinción importante de la radiación solar directa y la correspondiente elevación de la turbiedad del aire. El enfriamiento regional observado está de acuerdo con los resultados de los modelos sobre efectos atmosféricos de erupciones volcánicas, basados en la transferencia radiativa. Al analizar conjuntamente nuestros resultados con aquellos logrados mediante aviones de reconocimiento de la NASA y los sondeos de globos estratosféricos efectuados durante el mismo período, se llega a la conclusión de que este calentamiento regional, asociado a una importante extinción de la radiación solar, podría deberse al descenso masivo a la troposfera de los aerosoles volcánicos estratosféricos.
Paleomagnetic constraints on the volcanic history of Iztaccihuatl
Authors: Steele W. K.
Published: May 2021

Las direcciones de magnetización remanente de los 24 flujos de lava del volcán lztaccihuatl muestran polaridad magnética normal, sugiriendo que el presente cuerpo del volcán se formó durante el periodo de Brunhes Chron. Esta juventud relativa de la montaña ha sido substanciada por medio de recientes pruebas de K-Ar para comprobar la edad geológica. Los análisis de dispersión de V. G. P. conceden una estimación de la desviación secular de 14.2º. Este valor es semejante al predicho en la latitud de Iztaccihuatl por recientes modelos de variación secular y a una media de variación paleosecular determinada por la distribución mundial de los torrentes de lava. La concordancia de la cantidad estimada de dispersión con la esperada indica que la erupción de las lavas de este volcán ocurrió probablemente durante un intervalo de tiempo bastante grande, como para haber obt¡mido un ejemplo representativo de variación secular; lo que significa que el volcanismo se extendió por un periodo de tiempo más corto que el de Brunhes Chron pero más largo o comparable a la escala temporal de la variación secular. La media de V.G. P. en el volcán IztaccÍhuatl es estadísticamente indistinguible del polo geográfico.
Investigaciones geofísicas y características geoquímicas de las aguas hidrotermales: Volcán Poas, Costa Rica
Authors: Casertano L. , Borgia A. , Cigolini C. , Morales L. D. , Montero W. , Gomez M. , Fernandez J. F.
Published: May 2021

Se relatan los resultados más importantes de las investigaciones geoquímicas y geofísicas llevadas a cabo en la caldera activa del volcán Poás en el trienio 1980-82. Las aguas de la laguna caliente manifiestan una fuerte acidez (pH <1) debida al elevado contenido de Cfy so;. También la concentración de los iones metálicos es muy alta. La temperatura (T • 229ºC) de la mezcla de las aguas freáticas con los fluidos calientes, calculada mediante los geotermómetros químicos está comprendida en el intervalo de las temperaturas medidas para las aguas geotermales asociadas con rocas andesíticas. El aumento de la temperatura desde 92ºC, en diciembre de 1980, hasta 960°C, durante el periodo marzo-noviembre de 1981, en el sector nor-oriental de la cúpula lávica parece determinado por la fracturación de la zona superior de la masa lávica en enfriamiento en la chimenea volcánica más bien profunda.La fracturación, evidenciada por la crisis sísmica local de julio de 1980, determinó la exoluci6n desde abajo de fases  gaseosas con elevada temperatura. Reacciones superficiales de oxidación contribuyeron al aumento de la temperatura de los  gases.Las investigaciones geomagnéticas confirmaron que el aumento de temperatura afectó una zona restringida y superficial alrededor de la cúpula lávica. Esta interpretación hace excluir que el aumento de temperatura (de 92ºC hasta 960ºC) pudo ser determinado por la subida de masas magmáticas.
Mislocation of mexican earthquakes as reported in international bulletins
Authors: Singh S. K. , Lermo J.
Published: May 2021

La comparación de las localizaciones de temblores determinadas desde sismógrafos de campo o de estudios especiales con aquellos reportados en los boletines de PDE e ISC, sugieren que los temblores costeros superficiales en México están sistemáticamente mal localizados en estos boletines. En general, los epicentros tienen un corrimiento de cerca de 35 km hacia N 35°- 45°E. ISC, con mayor frecuencia que PDE, consigna profundidades de foco basadas en fases de profundidad. Estas profundidades, aunque mayores que las estimadas mediante modelos sintéticos o datos de campo, son más precisas que las de PDE. Sin embargo, por lo que concierne a la localización epicentral, hay poco que escoger entre los dos boletines. , Un pequeño aumento en el número de lecturas de estaciones mexicanas enviadas a PDE y ISC mejora aparentemente las localizaciones cerca de 10 km. Los errores en la localización se deben probablemente a la velocidad alta de la placa de Cocos bajo México. Estos errores sistemáticos deben de tomarse en cuenta en el uso de estos boletines.
Un análisis semiobjetivo para el campo de viento en los trópicos
Authors: Perez Garcia I.
Published: May 2021

El análisis semiobjetivo para el campo de viento en los trópicos se logar a través de: 1) Un análisis objetivo del campo de viento donde se usa el método de corrección sucesiva, 2) Un análisis subjetivo del campo de divergencia y vorticidad para el cual se utiliza una fotografía de satélite, 3) Un análisis objetivo de los mismos campos, lo que plantea el problema de valores iniciales y de frontera para dos ecuaciones tipo Poisson. A partir de estas ecuaciones se obtienen la función Potencial y Corriente por cuya derivación se obtiene finalmente el campo de viento.
Travel times and ray paths for continous media
Authors: Madrid A.
Published: May 2021

Las observaciones de tiempos de recorrido y amplitudes son de gran importancia en la interpretación sismológica tanto de fuente como de estructura. Se presenta aquí un método nuevo para obtener tiempos de recorrido y rayos para medios cuya velocidad de propagación de onda puede ser especificada analíticamente. Se proveen ejemplos en dos dimensiones y se desarrolla una extensión a tres dimensiones. Los resultados de aplicarlo a un modelo, se pueden usar en la construcción de sismogramas sintéticos o en esquemas de inversión de tiempos e interpretación. Numéricamente, este método es una extensión de otros métodos para resolver ecuaciones diferenciales; la técnica, usual de predictor - corrector se reemplaza por un criterio simple. Computacionalmente es sencillo; barato y arroja resultados precisos.
Breve revisión sobre la evolución tectónica de México
Authors: Morán Zenteno Dante Jaime
Published: May 2021

Los nuevos conceptos sobre la movilidad de la litosfera han conducido en los últimos años a un replanteamiento de los principales problemas tectónicos y paleogeográficos de México. La estructura geológica de México y Centroamérica revela una de las más complejas historias de integración y evolución cortical, caracterizada por episodios de concurrencia de diversos fenómenos geodinámicos y de interacción de segmentos continentales mayores y menores.
The petrology of the lower crust and upper mantle beneath southeastern Chihuahua, Mexico: a progress report
Authors: Nimz G.J. , Cameron K.L. , Cameron M. , Morris S.L.
Published: May 2021

En el basalto alcalino de la mina de peridotita La Olivina (localizada ~ISO km al SE de Chihuahua, Chih.), se encuentran granulitas y nódulos ultramáficos del manto superior o la corteza inferior bajo la forma de xenolitos. Estos xenolitos ultramáficos pertenecen a tres grupos que se diferencian por su composición de clinopiroxenos: grupo 1, alto magnesio (Mg/Mg + Fe• 0.90) y alto Cr2O3; grupo 11, moderado magnesio (Mg/Mg+ Fe• O. 76), alto AJ2O3 y alto TiO 2; y grupo 111, con composición intermedia entre I y 11 (grupo de transición). Los análisis de minerales primarios muestran que los xenolitos son similares a los de San Carlos, Arizona, E.U., Xalapasco de La Joya, San Luis Potosí, México y Kilbume Hole, New Mexico, E.U. Los xenolitos del manto de La Olivina pertenecen a tres grupos con distinta textura: grupo I, granoblástica (¿metamórfica?); grupo 11, granular allotriomórfica (¿ígnea?); y grupo 111, granular allotriomórfica (¿ígnea?) con algunas texturas porfiroclásticas (¿metamórfica?). Los xenolitos de corteza inferior de La Olivina son predominantemente gneises pelíticos y granulitos de piroxeno. Los gneises pelíticos presentan ensambles uniformes de granate+ cuarzo+ plagioclasa+ sanidina+ silimanita rutilo+ grafito. La mayoría de las granulitas de piroxeno tienen plagioclasa, aunque algunas presentan escapolita en vez de plagioclasa. Estas muestras del manto inferior son idénticas en ensamble de minerales y muy similares en geoquímica a los xenolitos del Kilbume Hole. Las granulitas y los gneises pelíticos tienen edades modelo de Nd de 1.1 a 1.2 m.a., usando un cociente inicial de condritas, o bien 1.6 m.a. si se usa el modelo de fuente empobrecida. La edad de 1.6 m.a. concuerda muy bien con las edades del Kilboume Hole, de aquí que se extiendan bajo el norte de México, al menos hasta el área de La Olivina, rocas precámbricas cratónicas, similares en edad, historia metamórfica y composición de protolito a las que están bajo Kilboume Hole.
Synthetic seismograms for a dislocation source by Finite-Difference techniques
Authors: Espíndola J. M. , Braile L. W.
Published: May 2021

Se presenta un método para calcular sismograrnas sintéticos de una dislocaci6n en dos dimensiones. El método utiliza diferencias finitas en coordenadas no ortogonales. Con esta tecnica es posible modelar medios heterogéneos con superficie libre y dislocaciones con diferentes características geometricas y cinematicas.