bluuebunny/crossref_metadata_2025 huggingface dataset:
OPTIMASI KONSENTRASI PELARUT DAN WAKTU EKSTRAKSI PEKTIN KULIT JERUK MANIS (CITRUS SINENSIS) DENGAN METODE MASERASI
Authors:   Jurusan Teknologi Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Brawijaya, Putri Widya , Nasution Anggi ,   Jurusan Teknologi Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Brawijaya, Tiffani Margaretha ,   Jurusan Teknologi Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Brawijaya, Wardana Aditya ,   Jurusan Teknologi Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Brawijaya
Published: April 2021

Limbah kulit jeruk dapat dimanfaatkan menjadi pektin dengan cara diekstrak. Pektin banyak digunakan pada industri pangan, salah satunya stabilizer. Penelitian bertujuan mengeta­hui konsentrasi pelarut dan lama waktu yang optimum pada proses ekstraksi untuk mendapat­kan rendemen, total pektin, dan tingkat kecerahan yang terbaik. Rancangan penelitian meng­gunakan Response Surface Methodology dengan Central Composite Design melalui software Design Expert 7.1.5. Kombinasi faktor perlakuan yaitu, konsentrasi asam oksalat (%) dan lama waktu ekstraksi (menit). Hasil penelitian menunjukkan nilai optimum konsentrasi pelarut asam oksalat sebesar 0,22% dengan lama waktu ekstraksi 90 menit 16 detik, menghasilkan 16,78% rendemen; 10,59% total pektin; dan 63,56 (L) tingkat kecerahan pektin. Kemudian, dilakukan karakterisasi pektin optimasi dengan hasil untuk kadar air 9,87%, berat ekivalen 901,60; kadar metoksil 5,59%; kadar asam galakturonat 51,45%; dan derajat esterifikasi 61,69%. Pektin yang dihasilkan sudah sesuai dengan standar International Pectin Producers Association (IPPA), kecuali pada berat ekivalen. Pektin hasil optimasi termasuk pektin metoksil rendah. Kata kunci : Ekstraksi; Kulit Jeruk Manis (Citrus sinensis); Pektin; Response Surface Methodology
Perception of Mental Health Care Professionals in Saudi Arabia on Computerized Cognitive Behavioral Therapy: Observational Cross-sectional Study
Authors: AlHadi Ahmad N , Alammari Khawla A , Alsiwat Lojain J , Alhaidri Nojood E , Alabdulkarim Nouf H , Altwaijri Nouf A , AlSohaili Shamma A
Published: May 2021

Background

Mental health disorders are common in Saudi Arabia with a 34% lifetime prevalence. Cognitive behavioral therapy (CBT), a type of psychotherapy, is an evidence-based intervention for the majority of mental disorders. Although the demand for CBT is increasing, unfortunately, there are few therapists available to meet this demand and the therapy is expensive. Computerized cognitive behavioral therapy (cCBT) is a new modality that can help fill this gap.

Objective

We aimed to measure the knowledge of cCBT among mental health care professionals in Saudi Arabia, and to evaluate their attitudes and preferences toward cCBT.

Methods

This quantitative observational cross-sectional study used a convenience sample, selecting mental health care professionals working in the tertiary hospitals of Saudi Arabia. The participants received a self-administered electronic questionnaire through data collectors measuring their demographics, knowledge, and attitudes about cCBT, and their beliefs about the efficacy of using computers in therapy.

Results

Among the 121 participating mental health care professionals, the mean age was 36.55 years and 60.3% were women. Most of the participants expressed uncertainty and demonstrated a lack of knowledge regarding cCBT. However, the majority of participants indicated a positive attitude toward using computers in therapy. Participants agreed with the principles of cCBT, believed in its efficacy, and were generally confident in using computers. Among the notable results, participants having a clinical license and with cCBT experience had more knowledge of cCBT. The overall attitude toward cCBT was not affected by demographic or work-related factors.

Conclusions

Mental health care professionals in Saudi Arabia need more education and training regarding cCBT; however, their attitude toward its use and their comfort in using computers in general show great promise. Further research is needed to assess the acceptance of cCBT by patients in Saudi Arabia, in addition to clinical trials measuring its effectiveness in the Saudi population.
Surgical Treatments for Legg-Calvé-Perthes Disease: Comprehensive Review
Authors: Maleki Arash , Qoreishy Seyyed Mohammad , Bahrami Mohammad Nabi
Published: May 2021

Background

Legg-Calvé-Perthes disease (LCPD) is a common public health problem that usually occurs between the ages of 4 and 8 years, but it can occur between the ages of 2 and 15 years. This condition occurs due to the interruption of blood supply to the femoral head. Up to now, different surgical and nonsurgical treatments, including femoral varus osteotomy, innominate osteotomy, pelvic osteotomies, triple osteotomy, Chiari osteotomy, and shelf acetabuloplasty, have been suggested for noncontainable LCPD hips.

Objective

The aim of this comprehensive review was to investigate the various surgical techniques used for LCPD.

Methods

An advanced electronic search of the English-language literature was performed from October 8 to 14, 2020. The electronic databases PubMed, MEDLINE, Web of Science, Embase, Ovid, and Google scholar were searched using appropriate search terms. A manual search of references also was performed. After retrieving the studies, duplicates were removed, and the remining studies were screened based on the title, abstract, and full text. The quality of the selected articles was assessed, and the required data were extracted from eligible articles.

Results

A total of 22 studies were included in the review. Based on the results of the reviewed studies, there are three main factors that influence the treatment outcomes in patients with Perthes disease. These factors are onset age, femoral head involvement severity, and treatment method. The disease has a poor prognosis in children over 8 years old, but this group of patients can also benefit from advanced surgical methods. In patients aged less than 6 years, the disease has a generally good prognosis, but in those aged between 6 and 8 years, its prognosis is variable. Thus, the need for surgical intervention requires close observation of signs. Once any head signs are observed, dynamic arthrography is beneficial before choosing the treatment approach.

Conclusions

This review provides clinicians with a brief guideline for the treatment of patients with LCPD.
Extracting Family History Information From Electronic Health Records: Natural Language Processing Analysis (Preprint)
Authors: Rybinski Maciej , Dai Xiang , Singh Sonit , Karimi Sarvnaz , Nguyen Anthony
Published: April 2021

BACKGROUND

The prognosis, diagnosis, and treatment of many genetic disorders and familial diseases significantly improve if the family history (FH) of a patient is known. Such information is often written in the free text of clinical notes.

OBJECTIVE

The aim of this study is to develop automated methods that enable access to FH data through natural language processing.

METHODS

We performed information extraction by using transformers to extract disease mentions from notes. We also experimented with rule-based methods for extracting family member (FM) information from text and coreference resolution techniques. We evaluated different transfer learning strategies to improve the annotation of diseases. We provided a thorough error analysis of the contributing factors that affect such information extraction systems.

RESULTS

Our experiments showed that the combination of domain-adaptive pretraining and intermediate-task pretraining achieved an F1 score of 81.63% for the extraction of diseases and FMs from notes when it was tested on a public shared task data set from the National Natural Language Processing Clinical Challenges (N2C2), providing a statistically significant improvement over the baseline (P<.001). In comparison, in the 2019 N2C2/Open Health Natural Language Processing Shared Task, the median F1 score of all 17 participating teams was 76.59%.

CONCLUSIONS

Our approach, which leverages a state-of-the-art named entity recognition model for disease mention detection coupled with a hybrid method for FM mention detection, achieved an effectiveness that was close to that of the top 3 systems participating in the 2019 N2C2 FH extraction challenge, with only the top system convincingly outperforming our approach in terms of precision.
Aggression in School Children: Role of gender, family factors and exposure to violence (Preprint)
Authors: Sehgal Mukul , Nayak Ajita
Published: May 2021

BACKGROUND

Increasing instances of aggression in school children has become a cause of great concern for educationists, parents and mental health professionals. With increased globalization and information overload, today’s child is exposed to influences which probably adversely modify the child’s behavior. These aggressive tendencies could affect the child’s academic, social functioning and also may lead to psychiatric problems. Hence, this study was planned to find out the amount of aggression among school children and various potential contributing factors for the aggressive behavior. Identifying these risk factors could help design preventive strategies among school children.

OBJECTIVE

OBJECTIVE: To evaluate the amount of aggression and its contributing factors among 10-12 year-old children.
SUBJECTS: The subjects involved the school children and their teachers in various schools across Mumbai. The age group of study was 10-12 years i.e. class 5th to class 8th
No. of subjects:-102

METHODS

A total of 102, 10-12 year-old school children (5th to 8th class) in the Mumbai metropolitan area were interviewed to assess the presence of aggression. A validated scale, Children’s Aggression Scale – Teacher version (CAS-T), was used to assess the presence of aggression. Children were assessed & scored on basis of this scale with questions answered by their teachers. Data was analyzed on the basis of each factor using unpaired t-test, ANOVA test and Kruskal-Wallis Test (Nonparametric ANOVA). Institutional ethics committee approval was taken for research at Seth GS Medical College, Mumbai, India.

RESULTS

A high level of aggression was present in 4% other children while moderate levels were present in 8%. Boys were found to be more aggressive than girls (p-value 0.003). Aggression scores were significantly higher in children from English medium and with poor academic performance. Children exposed to physical abuse and violence on Television showed significantly high aggression. Perceived parental conflict in boys was found to be significantly associated with lower aggression scores. Among the various factors studied, aggression scores showed highest correlation with exposure to violence on television for more than 2 hours/day (11.67 vs 3.19 p-value <0.001).

CONCLUSIONS

About 12% of schoolchildren in the 10-12years group show aggressive behavior needing interventions. Boys from abusive families, with poor academic performance and exposed to excessive violence on TV seem particularly at risk for developing aggressive behavior.

CLINICALTRIAL

Null
Toward a Behavior Theory–Informed and User-Centered Mobile App for Parents to Prevent Infant Falls: Development and Usability Study (Preprint)
Authors: Cooray Nipuna , Sun Si Louise , Ho Catherine , Adams Susan , Keay Lisa , Nassar Natasha , Brown Julie
Published: April 2021

BACKGROUND

Falls account for approximately 50% of infant injury hospitalizations, and caretaker behavior is central to preventing infant falls. Behavior theory–informed interventions for injury prevention have been suggested, but to date, few have been reported. The potential of using smartphones for injury prevention intervention delivery is also underexploited.

OBJECTIVE

This study aims to develop a behavior theory– and evidence-based as well as user-centered digital intervention as a mobile app for parents to prevent infant falls following agile development practices.

METHODS

Infant falls while feeding was selected as the fall mechanism to demonstrate the approach being taken to develop this intervention. In phase 1, the Behaviour Change Wheel was used as a theoretical framework supported by a literature review to define intervention components that were then implemented as a mobile app. In phase 2, after the person-based approach, user testing through think-aloud interviews and comprehension assessments were used to refine the content and implementation of the intervention.

RESULTS

The target behaviors identified in phase 1 were adequate rest for the newborn’s mother and safe feeding practices defined as prepare, position, and place. From behavioral determinants and the Behaviour Change Wheel, the behavior change functions selected to achieve these target behaviors were psychological capability, social opportunity, and reflective motivation. The selected behavior change techniques aligned with these functions were providing information on health consequences, using a credible source, instruction on performing each behavior, and social support. The defined intervention was implemented in a draft Android app. In phase 2, 4 rounds of user testing were required to achieve the predefined target comprehension level. The results from the think-aloud interviews were used to refine the intervention content and app features. Overall, the results from phase 2 revealed that users found the information provided to be helpful. Features such as self-tracking and inclusion of the social and environmental aspects of falls prevention were liked by the participants. Important feedback for the successful implementation of the digital intervention was also obtained from the user testing.

CONCLUSIONS

To our knowledge, this is the first study to apply the Behaviour Change Wheel to develop a digital intervention for child injury prevention. This study provides a detailed example of evidence-based development of a behavior theory–informed mobile intervention for injury prevention refined using the person-based approach.
Machine-Aided Self-diagnostic Prediction Models for Polycystic Ovary Syndrome: Observational Study (Preprint)
Authors: Zigarelli Angela , Jia Ziyang , Lee Hyunsun
Published: April 2021

BACKGROUND

Artificial intelligence and digital health care have substantially advanced to improve and enhance medical diagnosis and treatment during the prolonged period of the COVID-19 global pandemic. In this study, we discuss the development of prediction models for the self-diagnosis of polycystic ovary syndrome (PCOS) using machine learning techniques.

OBJECTIVE

We aim to develop self-diagnostic prediction models for PCOS in potential patients and clinical providers. For potential patients, the prediction is based only on noninvasive measures such as anthropomorphic measures, symptoms, age, and other lifestyle factors so that the proposed prediction tool can be conveniently used without any laboratory or ultrasound test results. For clinical providers who can access patients’ medical test results, prediction models using all predictor variables can be adopted to help health providers diagnose patients with PCOS. We compare both prediction models using various error metrics. We call the former model the patient model and the latter, the provider model throughout this paper.

METHODS

In this retrospective study, a publicly available data set of 541 women’s health information collected from 10 different hospitals in Kerala, India, including PCOS status, was acquired and used for analysis. We adopted the CatBoost method for classification, K-fold cross-validation for estimating the performance of models, and SHAP (Shapley Additive Explanations) values to explain the importance of each variable. In our subgroup study, we used k-means clustering and Principal Component Analysis to split the data set into 2 distinct BMI subgroups and compared the prediction results as well as the feature importance between the 2 subgroups.

RESULTS

We achieved 81% to 82.5% prediction accuracy of PCOS status without any invasive measures in the patient models and achieved 87.5% to 90.1% prediction accuracy using both noninvasive and invasive predictor variables in the provider models. Among noninvasive measures, variables including acanthosis nigricans, acne, hirsutism, irregular menstrual cycle, length of menstrual cycle, weight gain, fast food consumption, and age were more important in the models. In medical test results, the numbers of follicles in the right and left ovaries and anti-Müllerian hormone were ranked highly in feature importance. We also reported more detailed results in a subgroup study.

CONCLUSIONS

The proposed prediction models are ultimately expected to serve as a convenient digital platform with which users can acquire pre- or self-diagnosis and counsel for the risk of PCOS, with or without obtaining medical test results. It will enable women to conveniently access the platform at home without delay before they seek further medical care. Clinical providers can also use the proposed prediction tool to help diagnose PCOS in women.
Effects of Active Video Games on Health-Related Physical Fitness and Motor Competence in Children and Adolescents With Overweight or Obesity: Systematic Review and Meta-Analysis (Preprint)
Authors: Comeras-Chueca Cristina , Marin-Puyalto Jorge , Matute-Llorente Angel , Vicente-Rodriguez German , Casajus Jose Antonio , Gonzalez-Aguero Alex
Published: May 2021

BACKGROUND

Childhood obesity is one of the most important public health problems. Active video games (AVGs) have been proposed as an attractive alternative to increase energy expenditure and are being investigated to determine their effectiveness against childhood obesity.

OBJECTIVE

The aim of this study is to summarize the existing research and draw conclusions about the effects of AVGs on health-related physical fitness and motor competence in children and adolescents with overweight and obesity.

METHODS

The search strategy was applied to PubMed, MEDLINE, Web of Science, and SPORTDiscus, including randomized and nonrandomized controlled trials investigating the effects of AVG programs on health-related physical fitness and motor competence in children and adolescents with overweight and obesity. To measure the risk of bias in randomized and nonrandomized controlled trials, 2 different quality assessment tools were used. In total, 15 articles met the inclusion criteria, and the variables of interest were BMI, body fat percentage, cardiorespiratory fitness (CRF), waist circumference, fat-free mass, muscular fitness, and motor competence. A meta-analysis was performed.

RESULTS

Positive effects were found for BMI and body fat percentage, favoring the AVG group compared with a control group with no intervention (mean difference −0.209; 95% CI −0.388 to −0.031 vs mean difference −0.879; 95% CI −1.138 to −0.602). Positive effects seem to be observed for CRF. The effects of AVG interventions on muscular fitness, fat-free mass, waist circumference, and motor competence are unclear.

CONCLUSIONS

AVG programs showed positive effects on BMI, body fat percentage, and CRF. AVG could be a good strategy to combat childhood obesity.
Artificial Intelligence in Kidney Transplantation: A Scoping Review (Preprint)
Authors: Househ Mowafa , Alamgir Asma , Abdelaal Yasmin , Hussein Hagar
Published: April 2021

BACKGROUND

Artificial Intelligence technologies and big data have been increasingly used to enhance kidney transplant experts’ ability to make critical decisions and manage the care plan for their patients.

OBJECTIVE

To explore the use of AI technologies in the field of kidney transplantation as reported in the literature.

METHODS

Embase, CINAHL, PubMed and Google Scholar were used in the search. Backward reference list checking of included studies was also conducted. Study selection and data extraction was done independently by three reviewers. Data extracted was synthesized in a narrative approach.

RESULTS

Of 505 citations retrieved from the databases, 33 unique studies are included in this review. Artificial intelligence (AI) technologies in the included studies were used to help with diagnosis (n= 16), used as a prediction tool (n=15) and, also for supporting appropriate prescription for kidney transplant patients (n = 2). The population who benefited from the technique included patients who underwent kidney transplantation procedure (n = 24) and those who are potential candidate (n=6). The most prominent AI branch used in kidney transplantation care was machine learning with Random Forest (n=11) being the most used AI model, followed by Linear Regression (n=6).

CONCLUSIONS

Conclusion: AI is extensively being used in the field of kidney transplant. However, there is a gap in research on the limitation and obstacles associated with implementing AI technologies in kidney transplant. There is a need for more research to identify educational needs and standardized practice for clinicians who wish to apply AI technologies in critical transplantation-related decisions.
Automatic market research of mobile health apps for the self-management of allergic rhinitis (Preprint)
Authors: Bousquet Jean
Published: May 2021

BACKGROUND

Only a small number of apps addressing allergic rhinitis patients have been evaluated, which makes their selection difficult.

OBJECTIVE

We aimed to introduce a new approach to market research for allergic rhinitis apps based on the automatic screening of Apple App and Google Play stores.

METHODS

A JavaScript programme was devised for automatic app screening and applied in a market assessment of allergic rhinitis self-management apps. We searched the Google Play and Apple App stores of three countries (USA, UK and Australia) with the following search terms: hay fever, hayfever, asthma, rhinitis, allergic rhinitis. Apps were eligible if symptoms were evaluated. Results obtained with the automatic programme were compared to those of a blinded manual search. As an example, we used the search to assess apps that can be used to design a combined medication score for allergic rhinitis.

RESULTS

The automatic search programme identified 39 potentially eligible apps out of a total of 1,593 retrieved apps. Each of the 39 apps were individually checked, with 20 being classified as relevant. The manual search identified 19 relevant apps (out of 6,750 screened apps). Combining both methods, a total of 21 relevant apps were identified, pointing to a sensitivity of 95% and a specificity of 99% for the automatic method. Among these 21 apps, only two could be used for the combined symptom medication score for allergic rhinitis.

CONCLUSIONS

The programmed algorithm presented herein is able to continuously retrieve all relevant allergic rhinitis apps in the Apple App and Google Play stores, with high sensitivity and specificity. This approach has the potential to unveil the gaps and unmet needs of the apps developed so far.
Analisis Ekonomi on Grid PLTS untuk Rumah 2200 VA
Authors: Pramudita Brahmantya Aji , Aprillia Bandiyah Sri , Ramdhani Mohamad
Published: May 2021

Kebutuhan listrik adalah kebutuhan dasar masyarakat Indonesia. Peningkatan jumlah penduduk di Indonesia mengakibatkan kebutuhan listrik semakin meningkat. Sehingga, produksi energi listrik perlu ditingkatkan untuk memenuhi kebutuhan listrik di Indonesia. Namun, kebutuhan listrik tidak dapat dipenuhi oleh pembangkit listrik yang dimiliki oleh negara. Oleh karena itu, energi terbarukan didorong oleh pemerintah untuk menjaga ketahanan dan kemandirian energi. Mengkonversi energi surya menjadi energi listrik melalui perangkat panel surya adalah salah satu contoh alternatif untuk mendapatkan energi terbarukan. Pada penelitian ini, bertujuan untuk menganalisis terkait faktor keekonomian sistem on grid pembangkit listrik tenaga surya pada beban rumah tangga tipe 2200VA dengan dua jenis profil beban yang berbeda. Hasil perhitungan faktor keekonomian energi untuk sistem on grid pembangkit listrik tenaga surya berdasarkan atas perhitungan Net Present Cost (NPC) dan Break Even Point (BEP) dengan cara membandingkan hasil dari rumah sebelum dan sesudah menggunakan sistem on grid PLTS. Berdasarkan hasil analisis pada rumah teliti diperoleh penurunan daya sebesar 21,89% dibandingkan dengan rumah banding. Sehingga, NPC dapat turun sebesar 13,12%-15,31% dengan rentang tagihan listrik sebesar Rp 23.060.260,00 – Rp 25.195.970,00. Sedangkan, hasil analisis dengan melihat kecepatan modal kembali atau BEP menunjukkan bahwa sistem on grid PLTS pada rumah teliti lebih unggul dibandingkan dengan rumah banding dengan hasil pada jenis BEP Simple Payback sebesar 7,60 tahun dan Discounted Payback sebesar 8,73 tahun.
Pharmacist-Led Mobile Health Intervention and Transplant Medication Safety
Authors: Gonzales Haley M. , Fleming James N. , Gebregziabher Mulugeta , Posadas-Salas Maria Aurora , Su Zemin , McGillicuddy John W. , Taber David J.
Published: April 2021

Background and objectives

Medication safety events are predominant contributors to suboptimal graft outcomes in kidney transplant recipients. The goal of this study was to examine the efficacy of improving medication safety through a pharmacist-led, mobile health–based intervention.

Design, setting, participants, & measurements

This was a 12-month, single-center, prospective, parallel, two-arm, single-blind, randomized controlled trial. Adult kidney recipients 6–36 months post-transplant were eligible. Participants randomized to intervention received supplemental clinical pharmacist–led medication therapy monitoring and management via a mobile health–based application, integrated with risk-guided televisits and home-based BP and glucose monitoring. The application provided an accurate medication regimen, timely reminders, and side effect surveys. Both the control and intervention arms received usual care, including serial laboratory monitoring and regular clinic visits. The coprimary outcomes were to assess the incidence and severity of medication errors and adverse events.

Results

In total, 136 kidney transplant recipients were included, 68 in each arm. The mean age was 51 years, 57% were male, and 64% were Black individuals. Participants receiving the intervention experienced a significant reduction in medication errors (61% reduction in the risk rate; incident risk ratio, 0.39; 95% confidence interval, 0.28 to 0.55; P<0.001) and a significantly lower incidence risk of Grade 3 or higher adverse events (incident risk ratio, 0.55, 95% confidence interval, 0.30 to 0.99; P=0.05). For the secondary outcome of hospitalizations, the intervention arm demonstrated significantly lower rates of hospitalizations (incident risk ratio, 0.46; 95% confidence interval, 0.27 to 0.77; P=0.005).

Conclusions

We demonstrated a significant reduction in medication errors, adverse events, and hospitalizations using a pharmacist-led, mobile health–based intervention.
Os eventos de letramento de discentes do projeto Universidade Para Todos: uma análise qualitativa
Authors: Sampaio Fernando Álisson Santos , Nunes Tiago Alves
Published: April 2021

O Projeto Universidade para Todos (UPT) foi uma iniciativa da Secretaria da Educação da Bahia em parceria com universidades estaduais (UNEB, UEFS, UESB, UESC), cujo objetivo é o fortalecimento de uma política voltada à inserção de estudantes da rede pública estadual no ensino superior. Nesse contexto, este estudo objetiva analisar os eventos de letramento nos quais estudantes do projeto UPT estão imersos, no intento de saber e compreender quais textos são os mais acessíveis e que relações eles mantêm com esses eventos comunicativos. De caráter diagnóstico, o estudo possui como instrumento para geração do corpus o questionário misto, que foi aplicado a 31 discentes, oriundos do referido projeto, em duas escolas públicas da cidade de Salvador (BA). Ancoramo-nos, teoricamente, nos conceitos de letramento (ROJO, 2009; KLEIMAN, 2014; BAPTISTA, 2010) e eventos de letramento (STREET; CASTANHEIRA, 2014; STREET, 2000). Após a análise dos dados, notou-se que a natureza diversa do alunado faz com que o acesso aos eventos de letramentos também seja variado. Ademais, a relação que se mantém com os textos, igualmente, depende do acesso e diversidade de eventos comunicativos, influenciando, assim, na aprendizagem de língua portuguesa com vista ao objetivo que o UPT se propõe.
Dinámicas socioecológicas y valores sociales de servicios ecosistémicos en la cuenca del río Savegre, Costa Rica
Authors: Espinoza Cisneros Edgar , Ceciliano Calderón Linnette
Published: May 2021

Objetivo: examinar las dinámicas socioecológicas que explican las configuraciones espaciales de valores sociales sobre servicios ecosistémicos en la cuenca del río Savegre, Costa Rica. Metodología: se usaron un mapeo participativo, encuestas y entrevistas abiertas aplicadas a una muestra de 95 administradores de unidades productivas en la cuenca. Resultados: se encontró que, para este sistema, la zona de transición entre la cuenca alta y la cuenca media es importante en su concentración de valores sociales sobre servicios ecosistémicos. El valor social de biodiversidad fue muy priorizado y generalizado en términos espaciales. Por el contrario, otros valores sociales más abstractos, como el valor futuro y el estético, muestran tendencias más locales. Además, las transiciones históricas de usos de la tierra, así como factores biofísicos, como la topografía y eventos climáticos, se conjugan para determinar las configuraciones espaciales de los valores sociales. Limitaciones: la representación cartográfica de los valores sociales se basó en el uso de puntos debido a las características del programa utilizado (SolVES), por lo que no refleja asignaciones espaciales de valores sociales que comprenden la totalidad de la cuenca o un sector de la misma. Valor y conclusiones: se busca proveer insumos para el diseño de estrategias de sostenibilidad, sustentadas en evaluaciones socioambientales que trasciendan lo pecuniario e incorporen criterios socioculturales explícitos en términos espaciales.
Ozone and UV-B radiation anticorrelations at fixed solar zenith angles in southern Brazil
Authors: Guarnieri Ricardo André , Guarnieri Fernando Luís , Balbueno Contreira Danieli , Franco Padilla Liana , Echer Ezequiel , Kirsch Pinheiro Damaris , Passaglia Schuch Augusta Maria , Makita Kazuo , Schuch Nelson Jorge
Published: May 2021

En este trabajo se utilizaron datos del año 2000 de radiación UV-B medidos con un Radiómetro UV-B (Eko Instruments MS-210W) instalado en el sur de Brazil, en el Observatorio Espacial del Sur (OES/CRSPE/INPE - MCT), y datos de la columna total de ozono medidos por el TOMS (Total Ozone Mapping Spectrometer). Se compararon la concentración de ozono y de radiación UV-B para varios ángulos zenitales solares fijos. Con una selección de días claros se obtiene una anticorrelación de -0.86 para los ángulos zenitales de 70° y 55°, y de -0.97 para 40°. Así, las variaciones de ozono explicaron 74-94% de la variabilidad de UV-B durante el año 2000 en el OES. Se determinó que una disminución del 1% en la concentración de ozono produce un aumento del mismo orden en la radiación UV-B.
Cluster mission and data analysis for the March 2001 magnetic storm
Authors: Frutos Alfaro F. , Korth A. , Fränz M. , Mouikis C. G. , Kistler L. M. , Klecker B. , Rème H. , Dandouras I. , Teams CIS
Published: May 2021

La misión CLUSTER está destinada a estudiar la magnetosfera de la Tierra y las relaciones Sol-Tierra. Los 4 satélites de esta misión vuelan en una formación de tetraedro enviando datos en los que por primera vez pueden separar efectos temporales de efectos espaciales. Esta formación nos dará un mejor entendimiento de las características macroscópicas y microscópicas en la magnetosfera y el viento solar. Como un ejemplo presentamos los datos obtenidos de la espectrometría de iones durante una tormenta magnética intensa.
Magnetic-field aligned electric fields in collisionless space plasmas - a brief review
Authors: Fälthammar Carl Gunne
Published: May 2021

Los campos eléctricos alineados a los campos magnéticos juegan un importante papel en la dinámica de los plasmas magnetizados. Ellos permiten el desacoplamiento de los elementos de plasma debido a la violación de la condición de campo congelado, la ruptura del mapeo equipotencial, la eficiente aceleración de partículas cargadas y la liberación rápida de energía magnética. En los plasmas sin colisiones, que ocupan la mayor parte del universo, usualmente se asume que no existen. Sin embargo, una consecuencia muy importante de las mediciones in situ ha sido el reconocimiento de que tales campos eléctricos existen en los plasmas sin colisiones a pesar de la ausencia de la colisión friccional. Aunque indicios de su existencia están aún en mediciones en tierra, la prueba final está dada por la abrumadora evidencia de las observaciones in situ. Estas incluyen mediciones de algunos rasgos característicos de la función de distribución de las partículas, algunos experimentos y mediciones directas de estos campos eléctricos. Se han identificado algunos mecanismos que apoyan la existencia de estos campos eléctricos. Por ejemplo, la turbulencia, los solitones, los espejos magnéticos, las capas dobles y atrapamiento dinámico. Se ha observado que algunos de estos procesos son importantes en el fenómeno auroral, pero su importancia relativa aún no está bien entendida.
An interactive method for digital tree-ring width measurement
Authors: Rigozo Nivaor Rodolfo , Nordemann Daniel J. R. , Echer Ezequiel , Antunes Vieira Luis Eduardo , Prestes Alan
Published: May 2021

Presentamos un nuevo método interactivo para la determinación de la anchura de los anillos de los árboles. Se usa un escaner de la alta resolución y un microordenador en los que se trabaja con un programa para estudiar imágenes de anillos de árboles que se desarrolló dentro del ambiente Interactive Data Language (IDL 5.0). La ventaja principal de este método es que lleva a cabo un análisis de imágenes de anillos de árboles de manera interactiva sin necesitar equipo complejo y de alto costo. Se usó una prueba simple para verificar la precisión de las medidas de la anchura de los anillos de una muestra del árbol Pinus taeda del sur de Brasil.
Shear-wave velocity profile at the Texcoco strong-motion array site, Valley of Mexico
Authors: Stephenson Bill , Lomnitz Cinna
Published: May 2021

Se presenta un perfil de velocidades de ondas S obtenido en el sitio de la Red Sísmica de Texcoco, México. Se empleó el método de Penetrometría de Cono Sísmico (SCPT) hasta una profundidad de 39 metros bajo la superficie. Se encontró la capa dura a 28 metros y se perforó hasta 29 metros para continuar con el penetrómetro a profundidades mayores. Los resultados se comparan con los obtenidos en sísmica de reflexión y refracción, y con datos de inversión de microtemblores. Todos los estudios disponibles concuerdan entre sí, hasta llegar a la capa dura, pero hay algunas diferencias en cuanto al perfil a mayores profundidades. Las profundidades de las discontinuidades concuerdan con las reportadas en perforaciones de pozos.
Simulation of seismograms in a 2-D viscoelastic Earth by pseudospectral methods
Authors: M. Carcione José , Seriani Géza , B. Helle Hans , Plasencia Linares Milton P.
Published: May 2021

El algoritmo de modulación seudoespectral es mejorado y aplicado a la simulación de sismogramas generados por sismos oceánicos y continentales, como atención a la atenuación y a la modelación explícita de condiciones a la frontera en el fondo oceánico y a la simulación de la ventana de Rayleigh y la propagación en interfaces. El algoritmo se basa en los operadores diferenciales de Fourier y de Chebyshev con una técnica de decomposición de dominios, una malla para el fluido y otra para el sólido. Para la propagación se usa una relación de esfuerzo-deformación basada en variables de memoria. Entre los fenómenos modelados se incluyen las ondas de Scholte, las ondas evanescentes de Rayleigh y los modos dispersivos, así como la ventana de Rayleigh, un mínimo del coeficiente de reflexión en el fondo oceánico que nunca ha sido simulado con métodos directos. Hemos modelado los modos de Rayleigh (principalmente M11) y las ondas acopladas Rayleigh-Scholte, resolviendo la relación de dispersión para casos simples. Se modeló también efectos de inhomogeneidades aleatorias en la corteza y manto mediante una función de autocovarianza tipo von Kármán que simula los efectos de dispersión de ondas. El programa bidimensional permite una variación material general y una caracterización completa y exacta de la respuesta para sismos oceánicos y continentales. Se desarrolla un ejemplo para un sismograma originado en la región del Atlántico Sur.
A palaeomagnetic study of Upper Pliocene volcanic rocks in the area of the Levant Fault near Homs, western Syria
Authors: Abou-Deeb J. M. , H. Tarling D.
Published: May 2021

La desmagnetización térmica de 75 sitios en rocas basálticas, la mayor parte a menos de 5 km de la Falla Levante, identifica direcciones de remanencia consistentes en la mayoría de los sitios. Las polaridades identificadas son Normales, Inversas e Intermedias, dominando las Inversas. Los sitios Normales e Inversos están magnetizados similarmente, 5.6Â±5.3 A/m, en tanto que los sitios Intermedios o direcciones indefinidas están algo más fuertemente magnetizados, 11.9Â±9.5 A/m. Las susceptibilidades de campo bajo son consistentes, 30.9Â±15.2 mSI, lo que implica que el campo geomagnético pudo haber sido algo más intenso que durante las polaridades Normales o Inversas. Cuando la media de las direcciones de los sitios Normales se invierten, todos los sitios tienen valores similares de la inclinación media, 48.2° (Î´Inc. = 2.7°), pero la declinación media de las de los sitios muestra un patrón regional. Sitios de 3 regiones al oeste de la zona de Falla Levant (Marmarita, Qalat El-Hossen, Tel Kalakh) tienen declinaciones similares, 186° (Î´Dec. = 5.4°), declinaciones que son consistentes con las esperadas para esta parte de Arabia paraeste tiempo. Sin embargo, todos los sitios al este y cercanos a la zona de Falla Levant (Bahur, W. Ain-Kut, Mzeineh y Buqeia) tienen declinaciones más al este, en promedio de 154.0Â±12.0°. La diferencia de declinación, 37.3°, indica la presencia de bloques rotados adyacentes al lado oriental de la Falla Levante. Tal rotación es consistente con el desplazamiento de 25 km predicho para esta localidad y parece consistente con la subsecuente evolución volcánica y tectónica de la Falla Levante, sugiriendo rotaciones significativas y actividad sísmica durante los últimos 5 Ma.
Geochemistry of the hydrogeological reserve of Mérida, Yucatán, Mexico
Authors: Escolero O. , Marín L. E. , Steinich B. , Pacheco J. A. , Molina-Maldonado A. , M. Anzaldo J.
Published: May 2021

Se utilizaron datos hidrogeoquímicos para describir los procesos que modifican la calidad del agua subterránea en el noroeste de Yucatán. Se encontró que los procesos de disolución de rocas carbonatadas de gran pureza, la mezcla con agua salada y el intercambio iónico en calizas arcillosas están presentes en la zona en estudio. Las nuevas observaciones confirman los resultados de estudios previos sobre las medidas recomendadas para la conservación del agua subterránea en la zona. Se encontró agua salobre varios kilómetros tierra adentro, cuya presencia se debe a la intrusión de fondo de agua salada en pozos relativamente profundos o por la concentración del bombeo.
Seismicity, focal mechanisms, and stress distribution in the Tres Vírgenes volcanic and geothermal region, Baja California Sur, Mexico
Authors: Wong Victor , Munguía Luis
Published: May 2021

En octubre de 1993 se llevó a cabo un monitoreo sísmico en la región volcánica Las Tres Vírgenes con el propósito de registrar la actividad sísmica asociada a las estructuras volcánicas, al campo geotérmico y a la tectónica local. Se localizaron 257 microsismos con hipocentros en los edificios volcánicos y a lo largo de la falla de rumbo, lateral derecha conocida como falla La Virgen. La profundidad focal de los sismos varía desde los muy cercanos a la superficie de la Tierra hasta los 8 km. Lasprofundidades someras ocurren principalmente en los edificios volcánicos. Los sismos más profundos ocurren fuera del áreavolcánica. La magnitud de duración de los microsismos localizados varía entre 1 y 3. La razón Vp/Vs y los valores bajos de Q que se estimaron en la zona sugieren un material con propiedades heterogéneas bajo las estructuras volcánicas, principalmente hacia la falla el Azufre y la caldera El Aguajito, donde se ha reportado la actividad hidrotermal. La distribución de los ejes P y T de los mecanismos focales de 90 microtemblores sugieren que la región se encuentra bajo compresión en dirección N-S y extensión en dirección E-O, en concordancia con el régimen de esfuerzo regional impuesto por el sistema de fallas transformadas, NO-SE, lateral derecho, del Golfo de California.
Estimation of hydraulic conductivity on clay content in soil determined from resistivity data
Authors: Mousatov Aleksandr , Ryjov Albert
Published: May 2021

El contenido de arcilla en suelos areno-arcillosos influye sobre la permeabilidad hidráulica (coeficiente de filtración). Sepresenta una revisión de datos experimentales publicados que relacionan el coeficiente de filtración con el tipo litológico delsuelo y el tamaño de las partículas. A partir de cálculos teóricos, se modifican las conocidas fórmulas que relacionan el coeficientede filtración con el contenido de arcilla. Se estima el contenido de arcilla a partir de los datos interpretados por el método SEV,y se propone un procedimiento para la estimación del coeficiente de filtración: (a) cálculo del contenido de arcilla a partir de laresistividad del suelo y de la salinidad del agua subterránea, (b) estimación del coeficiente de filtración a partir del contenido dearcilla. Se presentan algunos ejemplos de la aplicación de esta metodología.
Archaeological calibration of remagnetized volcanic rocks from pottery firing kilns in Cuentepec, Morelos, Mexico
Authors: Alva-Valdivia L. M. , González-Rangel J. A. , Soler-Arechalde A. M. , López-Varela S. L. , López-Loera H.
Published: May 2021

Investigaciones etnoarqueológicas en Cuentepec incluyen experimentos durante la producción de cerámica, de donde es posible extraer conocimientos sociales a partir de la aplicación de técnicas arqueométricas. En este caso, el experimento trata sobre la confiabilidad de técnicas de fechamiento en arqueología. En Cuentepec, se usan pequeños hornos a cielo abierto para la fabricación de cerámica (comales de barro). Se tomaron muestras de roca volcánica que conformaban los hornos para verificar la confiabilidad de la dirección magnética registrada por las mismas y compararla con datos del Observatorio Geomagnético de Teoloyucan localizado cerca a la ciudad de México. Con el objeto de medir sus propiedades magnéticas se perforaron/obtuvieron en el laboratorio 47 núcleos pertenecientes a ocho muestras de bloque orientadas. Las curvas continuas de susceptibilidad magnética con altas temperaturas resultaron en muchos casos razonablemente reversibles, con puntos de Curie sugiriendo titanomagnetita de rica a pobre en titanio. Los parámetros de histéresis indican que todas las muestras caen en la región de tamaño de grano pseudo-dominio-simple, indicando probablemente una mezcla de granos multidominio más una cantidad significante de granos de dominio simple. Las curvas de adquisición de magnetización remanente isotermal fueron muy similares para casi todas las muestras. La saturación se alcanzó en campos moderados del orden de 100-120 mT, lo cual indica algunas espinelas como portadores de la remanencia. Concluimos que las muestras obtenidas de la parte interna de los bloques que forman los hornos, las más cercanas al fuego, guardan los registros más confiables del campo geomagnético. Esto significa que el calor producido por el fuego probablemente sólo remagnetizó las partes internas de los bloques.
The pyroclastic dikes of the Tertiary San Luis Potosí volcanic field: Implications on the emplacement of Panalillo ignimbrite
Authors: Torres-Hernández José Ramón , Labarthe-Hernández Guillermo , Aguillón-Robles Alfredo , Gómez-Anguiano Martín , Mata-Segura José Luis
Published: May 2021

Una serie de disques piroclásticos en el Campo Volcánico de San Luis Potosí está asociada a fallas regionales que cortan y basculan a la secuencia volcánica terciaria (37-27 Ma). Estos diques muestran sus raíces en las formaciones riolita San Miguelito e ignimbrita Cantera y están expuestos en los arroyos El Juachín y Las Cabras. Los diques tienen una inclinación casi vertical, su anchura es variable (máximo 60 cm) y están constituidos principalmente por ceniza volcánica, que consiste en vitroclastos o esquirlas de vidrio formadas por la fragmentación del material juvenil durante la erupción y de cristales fragmentados de cuarzo, sanidino y biotita. Los diques también y fragmentos de riolita. El acomodo de material es de forma tabular y paralela a las paredes del conducto. Los diques piroclásticos están asociados a las fallas normales formadas durante el Oligoceno medio, así como a los procesos volcánicos que dieron origen a la ignimbrita Panalillo.
Spectral signature of ultraviolet solar irradiance in Zacatecas
Authors: Pinedo V. J. L. , Mireles G. F. , Ríos M. C. , Quirino T. L. L. , Dávila R. J. I.
Published: May 2021

En este trabajo se presenta un análisis de la radiación espectral global ultravioleta (290-400 nm) registrada en Zacatecas, una ciudad vecina al trópico de cáncer, situada a 2500 m sobre el nivel del mar, latitud de 22°N y longitud de 102°O. Los espectros correspondientes han sido medidos mediante un espectroradiómetro Bentham con un paso de 0.5 nm de longitud de onda. Las mediciones muestran niveles de radiación ultravioleta (UV) relativamente elevados, que pueden ser característicos de las zonas vecinas al trópico de cáncer. Frente al aumento de incidencia de cáncer en la piel en la población del estado de Zacatecas, estas mediciones ponen en relieve la necesidad de formular un plan preventivo de daños.
Estimation of peak ground accelerations for Mexican subduction zone earthquakes using neural networks
Authors: García Silvia R. , Romo Miguel P. , Mayoral Juan M.
Published: May 2021

An extensive analysis of the strong ground motion Mexican data base was conducted using Soft Computing (SC) techniques. A Neural Network NN is used to estimate both orthogonal components of the horizontal (PGAh) and vertical (PGAv) peak ground accelerations measured at rock sites during Mexican subduction zone earthquakes. The work discusses the development, training, and testing of this neural model. Attenuation phenomenon was characterized in terms of magnitude, epicentral distance and focal depth. Neural approximators were used instead of traditional regression techniques due to their flexibility to deal with uncertainty and noise. NN predictions follow closely measured responses exhibiting forecasting capabilities better than those of most established attenuation relations for the Mexican subduction zone. Assessment of the NN, was also applied to subduction zones in Japan and North America. For the database used in this paper the NN and the-better-fitted- regression approach residuals are compared.
Human Footprints found in Central Mexico could be at least 40,000 years old
Authors: Martin-del- Pozo Ana Lillian , Gogichaishvili Avto , Urrutia Fucugauchi J. , Soler Arechalde Ana Maria
Published: May 2021

Recent studies from genetics of human populations and discoveries of new occupation sites have challenged the conventional model and earlier time framework of the earliest human migration into the American continent. Paleomagnetic analyses of a volcanic ash layer near Valsequillo, central Mexico, yields strong evidence of early arrival of humans in America.