bluuebunny/crossref_metadata_2025 huggingface dataset:
Modular Design of RF Front End for a Nanosatellite Communication Subsystem Tile Using Low-Cost Commercial Components
Authors: Ali Haider , Ali Anwar , Mughal M. Rizwan , Reyneri Leonardo , Sansoe Claudio , Praks Jaan
Published: April 2019

In recent years, the development market for low-cost nanosatellites has grown considerably. It has been made possible due to the availability of low-cost launch vectors and the use of “commercial off-the-shelf components” (COTS). The satellite design standardization has also helped a great deal to encourage subsystem reuse over a number of space missions. This has created numerous opportunities for small companies and universities to develop their own nanosatellite or satellite subsystems. Most COTS components are usually not space qualified. In order to make them work and withstand the harsh space environment, they need extra effort in circuit redesign and implementation. Also, by adopting the modularity concept and the design reuse method, the overall testing and nonrecurring development cost can be significantly reduced. This can also help minimize the subsystem testing times. The RF front-end design presented in this paper is also considered one of the better and feasible choices based on the above approach. It consists of an S-band transceiver that is fully implemented using COTS components. In the transmit chain, it is comprised of the transmitting CC2510 RF matching network and a power amplifier (PA) with an RF output power of up to 33 dBm which connects to an antenna using two RF switches. The receive chain starts from the antenna that is connected through two RF switches to the low-noise amplifier (LNA) that further connects to the receiving CC2510 via the RF matching network. The receiver sensitivity is -100 dBm. This is a half-duplex system using the same antenna for transmitting and receiving. The receiver and transmitter chains are isolated together using two RF switches which together provide an isolation of up to 90 dB at 2.4 GHz. The concept behind using two RF switches is to provide better isolation from the transmit chain to the LNA. The matching network of CC2510 has been designed in a symmetric fashion to avoid any delays. All the RF COTS used have been selected according to link budget requirements. The LNA, PA, and RF switches were tested individually for compliance. The passive components used in the overall design of the matching network are chosen on the basis of minimum dimension, least parasitic behaviour, and guaranteed optimum RF matching. Also, the RF COTS used are non-CMOS which makes them more robust against space radiations associated with the LEO environment and enables them to provide a radio communication data rate of up to 500 kbps in both uplink and downlink. The vacant spaces on the implemented PCB are shielded with a partial ground plane to avoid RF interference.
Robust Chaos of Cubic Polynomial Discrete Maps with Application to Pseudorandom Number Generators
Authors: Han Dandan , Min Lequan , Zang Hongyan , Yang Xiuping
Published: April 2019

Based on the robust chaos theorem of S‐unimodal maps, this paper studies a kind of cubic polynomial discrete maps (CPDMs) and sets up a novel theorem. This theorem gives general conditions for the occurrence of robust chaos in the CPDMs. By using the theorem, we construct a CPDM. The parameter regions of chaotic robustness of the CPDM are larger than these of Logistic map. By using a fixed point arithmetic, we investigate the cycle lengths of the CPDM and a Logistic map. The results show that the maximum cycle lengths of 1000 chaotic sequences with length 3 × 107 generated by different initial value conditions exponentially increase with the resolutions. When the resolutions reach 10−7 ~ 10−13, the maximum cycle lengths of the cubic polynomial chaotic sequences are significantly greater than these of the Logistic map. When the resolution reaches 10−14, there is the situation without cycle for 1000 cubic polynomial chaotic sequences with length 3 × 107. By using the CPDM and Logistic map, we design four chaos‐based pseudorandom number generators (CPRNGs): CPRNGI, CPRNGII, CPRNGIII, and CPRNGIV. The randomness of two 1000 key streams consisting of 20000 bits is tested, respectively, generated by the four CPRNGs. The result suggests that CPRNGIII based on the cubic polynomial chaotic generalized synchronic system has better performance.
Reliability Evaluation of Water‐Rich Loess Tunnel with Lining Crack Based on Extension Theory
Authors: Xue Xiaohui , Zhang Jun , Zhou Xinxing
Published: April 2019

Crack is the most prevalent disease of water‐rich loess tunnels, which impacts the tunnel safety and reliability. The study aimed to investigate the multi‐index of tunnel lining crack based on extension theory and reliability evaluation. A new evaluation model was built, and the matter‐element concept was used to describe the reliability of a water‐rich loess tunnel with lining crack. Crack width, crack depth, crack length, crack geometry, and water seepage of the Qiaoyuan tunnel were measured by intelligent crack measuring instrument, 10 m tape, laser scanner, and dosing cup. According to the analytic hierarchy process (AHP), the judgment matrix could be used to describe the relative importance of each index. Combining the maximum eigenvalue with checking consistency, the weight coefficients of 5 factors were calculated. A probabilistic statistic method and comparison of specification are performed to confirm the validity of extension theory in reliability evaluation. The results showed that the extension theory provided a reliability evaluation method of a water‐rich loess tunnel with lining crack.
Vehicle Text Data Compression and Transmission Method Based on Maximum Entropy Neural Network and Optimized Huffman Encoding Algorithms
Authors: Yang Jingfeng , Zhang Zhenkun , Zhang Nanfeng , Li Ming , Zheng Yanwei , Wang Li , Li Yong , Yang Ji , Xiang Yifei , Zhang Yu
Published: April 2019

Because of the continuous progress of vehicle hardware, the condition where the vehicle cannot load a complex algorithm no longer exists. At the same time, with the progress of vehicle hardware, the number of texts shows exponential growth in actual operation. In order to optimize the efficiency of mass data transmission in actual operation, this paper presented the text information (including position information) of the maximum entropy principle of a neural network probability prediction model combined with the optimized Huffman encoding algorithm, optimization from the exchange of data to data compression, transmission, and decompression of the whole process. The test results show that the text type vehicle information based on compressed algorithm to optimize the algorithm of data compression and transmission can effectively realize data compression. It can also achieve a higher compression rate and data transmission integrity, and after decompression it can basically guarantee no distortion. The method proposed in this paper is of great significance for improving the transmission efficiency of vehicle text information, improving the interpretability and integrity of text information, realizing vehicle monitoring, and grasping real‐time traffic conditions.
Beneficial Role of Phytochemicals on Oxidative Stress and Age-Related Diseases
Authors: Forni Cinzia , Facchiano Francesco , Bartoli Manuela , Pieretti Stefano , Facchiano Antonio , D’Arcangelo Daniela , Norelli Sandro , Valle Giorgia , Nisini Roberto , Beninati Simone , Tabolacci Claudio , Jadeja Ravirajsinh N.
Published: April 2019

Aging is related to a number of functional and morphological changes leading to progressive decline of the biological functions of an organism. Reactive Oxygen Species (ROS), released by several endogenous and exogenous processes, may cause important oxidative damage to DNA, proteins, and lipids, leading to important cellular dysfunctions. The imbalance between ROS production and antioxidant defenses brings to oxidative stress conditions and, related to accumulation of ROS, aging-associated diseases. The purpose of this review is to provide an overview of the most relevant data reported in literature on the natural compounds, mainly phytochemicals, with antioxidant activity and their potential protective effects on age-related diseases such as metabolic syndrome, diabetes, cardiovascular disease, cancer, neurodegenerative disease, and chronic inflammation, and possibly lower side effects, when compared to other drugs.
Breast Feeding Practice: Positioning and Attachment during Breast Feeding among Lactating Mothers Visiting Health Facility in Areka Town, Southern Ethiopia
Authors: Degefa Nega , Tariku Befikadu , Bancha Takalign , Amana Gizachew , Hajo Abdo , Kusse Yisehak , Zerihun Eshetu , Aschalew Zeleke
Published: April 2019

Background. Breastfeeding is the act of milk conveyance from the mother to the infant. Adequate nutrition during infancy and early childhood are mandatory to ensure growth, health, and development of children to their maximum potential. The positioning of the baby’s body is important for maintaining good attachment and successful breastfeeding. Most difficulties of breastfeeding can be avoided altogether if good attachment and positioning can be achieved at the first and early feeds. Plenty of studies have been conducted to explore factors affecting breastfeeding practice in general; however, there is a meagerness of evidence that assesses factors affecting attachment and positioning during breastfeeding specifically. Therefore, the current study was aimed to assess positioning and attachment during breastfeeding among lactating mothers visiting health facilities of Areka town. Methods. an institution-based cross-sectional study was conducted by using observational checklist adopted from the World Health Organization breastfeeding observation form. Maternal-related characteristics were collected by using a structured and pretested questionnaire. The study was conducted from April to June 2017. Respondents were selected by using a systematic random sampling technique. Descriptive summaries were done to present pertinent findings and a chi-square test was used to check association between variables. Result. There was poorer positioning among primipara mothers (47.1%) than multipara mothers (28.7%). A poor attachment was also more apparent among primipara mothers which were more (31.1%) than the multipara (27.1%) mothers. Conclusion. Younger mothers (<20 years old), the primipara, and those who have no formal education deserve more attention, support, and direction to make sure that they can achieve proper positioning and attachment during breastfeeding at the first and early feeds.
Lumbopelvic Fixation for Sacral Insufficiency Fracture Presenting with Sphincter Dysfunction
Authors: Maki Satoshi , Nakamura Kaito , Yamauchi Tomonori , Suzuki Takeshi , Horii Manato , Kawamura Koui , Aramomi Masaaki , Sugiyama Hiroshi , Ohtori Seiji
Published: April 2019

Sacral insufficiency fractures (SIFs) are common in the elderly. In patients with SIF, objective neurological abnormalities such as sphincter dysfunction or leg paresthesia are uncommon. We present a case of SIF accompanied by spinopelvic dissociation with late neurological compromise treated by spinopelvic fixation. A 61-year-old woman presented to our hospital with low back pain without obvious trauma history. She had a past history of eosinophilic granulomatosis with polyangiitis and treatment with steroids. Her low back pain became worse, and she started to have radiating left posterior thigh pain and motor weakness in the left ankle and both great toes with symptoms of stress urinary incontinence, constipation, and loss of anal sensation. Magnetic resonance imaging revealed an H-shaped sacrum fracture. We attributed the neurological symptoms to unstable SIF and performed lumbopelvic fixation. After the surgery, her leg pain and symptoms of stress urinary incontinence improved markedly, as did anal sensation. At a 6-month follow-up, the patient reported no low back pain and she was walking independently without pelvic complaints. CT showed bone union was achieved. Even minimally displaced SIF in patients with osteoporosis can be a cause of bowel and bladder disturbance. Lumbopelvic fixation is a treatment option for SIF with spinopelvic dissociation presenting neurological deficit.
Metastasizing Malignant Granular Cell Tumor (Abrikossoff Tumor) of the Anterior Abdominal Wall, with Prolonged Survival
Authors: Alnashwan Yara A. , Ali Khaled A. H. , Amr Samir S.
Published: April 2019

Malignant granular cell tumor (MGCT) is a rare high-grade mesenchymal tumor of Schwann cell origin. MGCTs commonly affect thigh, extremity, and trunk; however, involvement of the abdominal wall is quite rare. It has poor prognosis with 39% mortality rate in 3-year interval. We report a 50-year-old female who had MGCT arising in the anterior abdominal wall and developed massive metastatic deposits in both lungs and in the right inguinal lymph nodes, with prolonged survival for 11 years. A brief review of the literature is presented.
Vertical Seismic Effect on the Seismic Fragility of Large‐Space Underground Structures
Authors: He Zhiming , Chen Qingjun
Published: April 2019

The measured vertical peak ground acceleration was larger than the horizontal peak ground acceleration. It is essential to consider the vertical seismic effect in seismic fragility evaluation of large‐space underground structures. In this research, an approach is presented to construct fragility curves of large‐space underground structures considering the vertical seismic effect. In seismic capacity, the soil‐underground structure pushover analysis method which considers the vertical seismic loading is used to obtain the capacity curve of central columns. The thresholds of performance levels are quantified through a load‐drift backbone curve model. In seismic demand, it is evaluated through incremental dynamic analysis (IDA) method under the excitation of horizontal and vertical acceleration, and the soil‐structure‐interaction and ground motion characteristics are also considered. The IDA results are compared in terms of peak ground acceleration and peak ground velocity. To construct the fragility curves, the evolutions of performance index versus the increasing earthquake intensity are performed, considering related uncertainties. The result indicates that if we ignore the vertical seismic effect to the fragility assessment of large‐space underground structures, the exceedance probabilities of damage of large‐space underground structures will be underestimated, which will result in an unfavorable assessment result.
Study on the Evolution Characteristics of Two‐Zone Failure Mode of the Overburden Strata under Shallow Buried Thick Seam Mining
Authors: Yang Daming , Guo Wenbing , Tan Yi
Published: April 2019

There are risks of water burst and sand inrush in the working face of the Northwest Mining Area in China. Based on the 22407 working face of Halagou coal mine, the evolution characteristics and mechanism of a two‐zone failure mode of the overburden strata in shallow buried thick seam mining were thoroughly analysed using physical modelling, theoretical analysis, on‐site observation, and other research methods. A method to calculate the overburden fissure width was also proposed. The analysis results indicated that the evolution of a two‐zone failure mode of the overburden strata mainly includes four stages: gestation, formation, transformation, and stabilization. In the transformation stage, a fracture zone is transformed into a caving zone. The caving zone and fracture zone are separately transferred to the working face direction based on the structure type of key strata of voussoir beam and cantilever beam after the heights of the two zones stabilize, and the “two‐belt” cracks are mainly composed of inclined and horizontal fissures. Based on this study, the mechanism of the two‐zone failure mode of overburden strata development was analysed according to the mining height and overburden strata key layer structure. This paper serves as a guide for safe and green mining on shallow buried thick seams.
Systematic revision of the fruit fly genus Carpophthoromyia Austen (Diptera, Tephritidae)
Authors: DE MEYER MARC
Published: April 2019

The Afrotropical fruit fly genus Carpophthoromyia Austen is revised. In total, 17 species are recognized of which 7 are new to science: C. debeckeri sp.n., C. dividua sp.n., C. flavofasciata sp.n., C. interrupta sp.n., C. radulata sp.n., C. schoutedeni sp.n. and C. virgata sp.n.. Carpophthoromyia amoena Enderlein is considered a junior synonym of C. vittata (Fabricius). C. angusticeps Bezzi is considered not to belong to Carpophthoromyia but to the gastrozonine genus Clinotaenia Bezzi: Clinotaenia angusticeps (Bezzi) comb.nov. A lectotype is designated for each of C. litterata, C. pseudotritea, and C. tessmanni. All species are described or re-described, with illustrations of wing patterns and male and female terminalia where deemed necessary for unambiguous identification. An identification key to species is provided.
Two new species of the feather mite subfamily Pterodectinae (Acari: Astigmata: Proctophyllodidae) from Brazil
Authors: HERNANDES FÁBIO A. , VALIM MICHEL P.
Published: April 2019

We describe two new pterodectine feather mites (Analgoidea: Proctophyllodidae) from Brazilian passerines (Passeriformes): Pterodectes amaurochalinus sp. n., from Turdus amaurochalinus Cabanis (Turdidae), and Dolichodectes neotropicus sp. n., collected from Elaenia chiriquensis Lawrence (Tyrannidae). A key to species of the genus Dolichodectes is presented.
Himantura hortlei n. sp., a new species of whipray (Myliobatiformes: Dasyatidae) from Irian Jaya, Indonesia
Authors: LAST PETER R. , MANJAJI-MATSUMOTO MABEL , KAILOLA PATRICIA J.
Published: April 2019

The Indo-Malay region, which is represented by at least 17 whiprays of the genus Himantura, has the richest dasyatid fauna of any region. Himantura hortlei n. sp. is described based on specimens from coastal marine and estuarine habitats in the Arafura Sea off Irian Jaya (southwestern New Guinea). The mature male holotype was caught in the estuary of the Minajerwi River. It is a moderately large ray that reaches at least 0.7 m disc width and 2.4 m total length. This species can be distinguished from most of its congeners by the combination of a relatively narrow, heart-shaped disc with a very long angular snout, very small eyes, a non-protrusible mouth, no deep circumoral grooves, larger and more slowly developing denticles, a less well-developed lateral prepelvic process, a yellowish ventral surface when fresh, denticles present along the upper anterior snout margin, and a denticle band ending well forward of the eyes in adults.
Growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus) fed leaves extract of Myrmecodia tuberosa
Authors: NUGROHO RUDY AGUNG , HARDI ESTI HANDAYANI , SARI YANTI PUSPITA , ARYANI RETNO , RUDIANTO RUDIANTO
Published: April 2019

Abstract. Nugroho RA, Hardi EH, Sari YP, Aryani R, Rudianto. 2019. Growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus) fed leaves extract of Myrmecodia tuberosa. Nusantara Bioscience 11: 89-96. The application of plant extract in the aquaculture field is gaining momentum. This study aimed to determine the effects of M. tuberosa Jack leaves extract on the growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus). 400 fish with an initial average weight of 1.54 ± 0.02g were randomly divided into five groups and fed with different concentration of M. tuberosa Jack leaves extract (0.25, 0.5, 1, 2%) and control diet for 80 days. Growth performance, feed conversion rate, feed efficiency, survival rate, morphometric, and hematological profile of the fish were evaluated at the end of the trial. The results found that fish fed 0.5-1% concentration had significantly higher (P<0.05) growth, feed conversion rate, feed efficiency, morphometric value, survival, white blood cell, hemoglobin, neutrophil, lymphocyte, and monocyte than control. Meanwhile, supplementation of 2% MTE in the diet of fish reduced growth, feed utilization, viscerosomatic index, and morphometric values but increased red blood cell. All the supplemented diets decreased platelet of fish. The findings indicated that supplementation 0.5-1% of MTE is beneficial to the growth and blood profile of fish through the increment of growth indices, feed utilization, white blood cell, hemoglobin, neutrophil, lymphocyte, and survival rate of fish.
Reprint Retrospective: "Branding Politics: Shopping for Change?" from AuthenticTM: The Politics of Ambivalence in a Brand Culture
Authors: Banet-Weiser Sarah , Sturken Marita
Published: April 2019

Abstract: This is a reprint of Sarah Banet-Weiser's chapter "Branding Politics: Shopping for Change?" from her 2012 book AuthenticTM: The Politics of Ambivalence in a Brand Culture (NYU Press). Preceding the reprint is an interview between Sarah Banet-Weiser (London School of Economics) and Marita Sturken (New York University) about the book's inspiration and contributions, branding as culture, brand experiences, authenticity, the intersection of brand and political cultures, activism, and feminism. The interview and reprint seek to inspire reflection and discussion about the ambivalence and possibilities that come when branding, consumption, and politics mix. Shopping has become more than a simple transaction for many consumers—it has become a form of commodity activism that requires brands to be authentic, politically aware, and adaptive in an increasingly social and globally connected media environment.
An Examination of Changing Values in Israeli Television Commercials between 2012 and 2016
Authors: Lavie-Dinur Amit , Karniel Yuval
Published: April 2019

Abstract: Researchers have argued that advertisers use the public's values and conventional beliefs in their own interests, which allows us to learn about the dominant values in a society from its advertisements. In this article, we analyze the change in values reflected in Israeli television commercials between 2012 and 2016, and uncover messages that advertisers did not necessarily intend to convey. The analysis of the commercials in this study reveals how advertising has dealt with major changes in Israeli society. On the one hand, television commercials represented Israeli social values that appeared to have the intention of creating a positive feeling in the members of the target audience, such as a sense of home, familiarity, and belonging. In many cases, advertisers based their advertisements on family values, empathy, trust, and a pleasant aesthetic environment. But, at the same time, opposite messages were also being represented. We found that the television commercials emphasized inadequacy, social division, distrust, infidelity, irresponsibility, financial anxiety, and the subversion of child-adult and male-female relations.
Roundtable on Sex in Advertising, Part II
Authors: Bass Debra , Bronstein Carolyn , Kilbourne Jean , Lambiase Jacqueline , Mechlin David , Reichert Tom , Zuzarte Raquelle M. , O'Barr William M. , Timke Edward
Published: April 2019

Abstract: An important topic among academics and industry practitioners is how sex has been used in advertising. To contribute to this conversation, Advertising & Society Quarterly assembled a group of leading advertising practitioners, scholars, and activists at Duke University's Hartman Center for Sales, Advertising, and Marketing History for a roundtable on sex in advertising. Part II of the Roundtable on Sex in Advertising covers what participants classify as the best and worst ads representing sex, the importance of brands and agencies to drive change in how sex is used in advertising, the need to consider the nature of the advertised product, empathy, media literacy, and the need for more academic-practitioner dialogues about important topics like sex in advertising.
Diversity and Multiculturalism in Advertising: An Interview with Julia Huang
Authors: Huang Julia , Grow Jean M.
Published: April 2019

Abstract: In this interview, Julia Huang, Founder and CEO of California-based InterTrend Communications, talks about the history and development of Asian American advertising and the challenges faced by multicultural agencies. Julia tells the story of founding and developing her own agency, the experience of being an Asian American woman in advertising, and the importance of storytelling in representing identities in advertising. She speaks to opportunities for a more inclusive future and the need for practitioners and academics to come together to have important conversations about how to make advertising more reflective of society's many communities.
Cultivating Courageous Talent: An Interview with Deb Morrison on Teaching Advertising and Brand Responsibility
Authors: Morrison Deborah , Timke Edward
Published: April 2019

Abstract: Award-winning mentor and teacher Deb Morrison talks about her place as an outlier in the world of academia, first at the University of Texas at Austin and then at the University of Oregon. Rather than focusing on the insular world of researching advertising for the academy's sake, Morrison explains how she works to build bridges between academia and industry in a variety of ways through her teaching: theoretically grounded case studies, visits to the field, and connecting her students with innovative industry leaders. In her teaching and mentoring, she aims to cultivate talented individuals who find their niche but always keep critical thinking, authenticity, responsibility, and courage in mind. Rather than training students to make advertising effective only for the bottom line, Morrison encourages her students to think about how advertising can have value and positive impact in the world.
Jocs de conversa: qüestionaris en entrevistes
Authors: Iglesias Nieto Maria Lluïsa
Published: April 2019

El curs acadèmic 2017-2018 els alumnes del Màster en Comunicació i Mediació Cultural participaren en la creació d’un programa de ràdio en directe. En aquest programa entrevistaren molt diverses personalitats de la cultura valenciana. Per tancar el programa, l’entrevistador omplia un qüestionari del tipus «Què portaria a una illa deserta?» o «Quina és la vostra paraula favorita?». Es tracta de preguntes diferents de la resta de l’entrevista, però d’alguna manera semblen pertànyer al gènere de l’entrevista. En aquest article s’explica com un joc de sala anglés s’ha convertit en un subgènere de l’entrevista. En primer lloc, situarem l’entrevista en el mapa dels gèneres periodístics i en revisarem els orígens. A continuació, parlarem de l’evolució del qüestionari Proust i la seua aplicació en entrevistes literàries en diferents mitjans com la premsa i la televisió. A més, veurem les noves aplicacions dels qüestionaris que hem conegut al segle XXI. Pel que fa a la ràdio, presentarem la pràctica periodística d’entrevistar representants de la cultura valenciana en directe al programa de ràdio Café Gadea. Ens centrarem en qüestionaris d’inspiració proustiana realitzats en entrevistes amb els clients i en comentarem les respostes. Per concloure, indicarem les conclusions extretes d’aquest estudi i pràctica acadèmica.
Fundamentos para una teoría de la medicina, de Fernando Lolas (Niram Art, Madrid/Londres/Nova York, 2015, 160 pàgines)
Authors: Koťátková Adéla
Published: April 2019

Reseña de: Fundamentos para una teoría de la medicina, de Fernando Lolas (Niram Art, Madrid/Londres/Nova York, 2015, 160 pàgines).
Kontroversi Perempuan Sebagai Wali Nikah
Authors: Najib Agus Moh.
Published: April 2019

The concept of waliin marriage contract is essentially a mean to ascertain the attainment of the goal of a marriage, that is to maintain harmony between a husband and wife in their familial life. The institution of wali (guardianship) is meant to guarantee the rights, safety and welfare of the underage brides before and after they enter their marital life. Thus, it can be said that wali for a brU1e is needed when she is not adult yet, and has no capability to conduct legal acts by herself Meanwhile a waliwho is meant to be her protector should be an adult person with sound judgment and ability to perform legal acts so that the wali can perform the duties appropriately. If the main condition of wali is adulthood and soundness of judgment, then women, not only men, can be a wali, as it is believed by the Hanafis.
Understanding teacher shortages: An analysis of teacher supply and demand in the United States
Authors: Sutcher Leib , Darling-Hammond Linda , Carver-Thomas Desiree
Published: April 2019

This paper reviews the sources of and potential solutions to teacher shortages in the United States. It describes the sources of current and projected increases in teacher demand relative to enrollments, shifts in pupil-teacher ratios, and attrition. It places these in relation to recent declines in teacher supply and evaluates evidence of shortages in fields like mathematics, science, special education, and educators for English learners, as well as in particular parts of the country. Our analysis using national databases through 2016 predicted an estimated annual teacher shortage of approximately 112,000 teachers in 2017-18. Our recent review of state teacher workforce reports estimated 109,000 individuals were uncertified for their teaching positions in the US in 2017, roughly approximating our projections. We discuss the factors driving shortages and, based on previous research, identify responses that might ameliorate these trends.
Recruitment, employment, retention and the minority teacher shortage
Authors: Ingersoll Richard , May Henry , Collins Gregory
Published: April 2019

This study examines and compares the recruitment, employment, and retention of minority and nonminority school teachers over the quarter century from the late 1980s to 2013. Our objective is to empirically ground the ongoing debate regarding minority teacher shortages and changes in the minority teaching force. The data we analyze are from the National Center for Education Statistics’ nationally representative Schools and Staffing Survey (SASS) and its longitudinal supplement, the Teacher Follow-up Survey (TFS). Our data analyses document the persistence of a gap between the percentage of minority students and the percentage of minority teachers in the US. But the data also show that this gap is not due to a failure to recruit new minority teachers. In the two decades since the late 1980s, the number of minority teachers almost doubled, outpacing growth in both the number of White teachers and the number of minority students. Minority teachers are also overwhelmingly employed in public schools serving high-poverty, high-minority and urban communities. Hence, the data suggest that widespread efforts over the past several decades to recruit more minority teachers and employ them in disadvantaged schools have been very successful. But, these efforts have also been undermined because minority teachers have significantly higher turnover than White teachers and this is strongly tied to poor working conditions in their schools.
Equitable access to capable teachers: The states respond
Authors: Sykes Gary , Martin Kacy
Published: April 2019

This study examined a sample of plans that states submitted to the U.S. Education Department in 2015, pursuant to requirements in the Elementary and Secondary Education Act Title I, Part A. Plans were aimed at redressing inequities in access to qualified teachers as this problem has emerged in states and districts across the country. A considerable body of research has demonstrated that teachers are inequitably distributed to the disadvantage of low income and historically under-served students.  Based on descriptive and inferential coding of these plans, the study reaches several conclusions. First, the federal planning mandate has served as an impetus for developing state data systems that track teacher distributions.  Second, many of the strategies states are proposing are not directly relevant, targeted, or fully committed in terms of resources and implementation. Third, in states with highly rated plans, the strategies address fundamental, underlying conditions while offering a comprehensive range of targeted strategies to improve recruitment, support, and retention of teachers in schools serving concentrations of low income and under-served students. Progress on this issue is underway with much that remains to be done.
Breaking the cycle of teacher shortages: What kind of policies can make a difference?
Authors: Darling-Hammond Linda , Podolsky Anne
Published: April 2019

Teacher shortages have recurred in the United States over many decades. This article introduces a special issue of EPAA that seeks to better understand the factors that contribute to the insufficient supply and inequitable distribution of qualified teachers, as well as the recurrences of teacher shortages. Together, the six articles in this issue help provide an empirical understanding of the current state of the supply, demand, and distribution of America’s public school teachers. This lead article provides an overview of the current status of teaching in the U.S. and outlines the volume’s findings about the key contributors to teacher supply, demand, and shortages of qualified teachers; the subject areas and locations in need of teachers; the determinants of high turnover for particular types of teachers; promising policies to recruit and keep teachers; and states’ attention to these policies. We hope the findings from this volume enable a better understanding of the obstacles and solutions to providing all students with high-quality teachers.
Preparation of Silicone-Modified Acrylate Latex and its Application for Low-Emission Printing of PET Fibre
Authors: Ai Li , Cao Hongmei , Zhu Yawei
Published: April 2019

Attempts were made to find a more environmentally friendly technique for the printing of polyester (PET ) fabric, acting as an alternative to a usual disperse dye direct-printing process by using a plenty of water and salt and producing effluent contaminants. The low-emission printing technique includes the recipe containing disperse dye paste, synthetic thickener and the water-based silicone-modified acrylate and high-temperature curing process. The water-based silicone-modified acrylate for adhesive coating of polyester (PET) fibres was synthesized using butyl acrylate (BA), eight four methyl siloxane (D4), acrylonitrile (AN), styrene (St), methyl acrylic acid (MAA) and N-methylol acrylamide (NMA).The results showed that the silicone-modified acrylate adhesive could increase the percentages of dye fixation and the colour strength. The superior colour fastness (≥level 4) with the low-emission printing process was realized. The wastewater stream produced by the technique had a residual dye concentration of 2.62 mg/L, which was reduced by approximately 19 times that produced by traditional direct printing. The effluent wastewater drainage was reduced by 76.9%.
Chromium-modified cobalt molybdenum nitrides as catalysts for ammonia synthesis
Authors: Adamski Paweł , Nadziejko Marlena , Komorowska Agata , Sarnecki Adam , Albrecht Aleksander , Moszyński Dariusz
Published: April 2019

The influence of chromium compounds on the properties of cobalt molybdenum nitrides was studied. CoMoO4 obtained by precipitation from cobalt and molybdenum salts was modified by the addition of chromium(III) nitrate. A mixture of cobalt-molybdenum nitrides, Co2Mo3N and Co3Mo3N, was formed by ammonolysis of modified CoMoO4. The concentration of Co2Mo3N decreases with increasing chromium content. The specific surface area of cobalt molybdenum nitrides consisting of 2 wt% of Cr atoms increased by 50% in comparison to pure cobalt molybdenum nitrides. The catalytic activity of obtained catalysts in ammonia synthesis process decreases with rising of chromium concentration.
The Use Of Chemical Composition And Additives To Classify Petrol And Diesel Using Gas Chromatography–Mass Spectrometry And Chemometric Analysis: A Uk Study
Authors: Suppajariyawat Praew , Andrade Ana Flavia Belchior de , Elie Mathieu , Baron Mark , Gonzalez-Rodriguez Jose
Published: April 2019

The identification of the fuel found in a crime scene and establishing its source is important for forensic investigations. In this study petrol and diesel samples were analysed in order to identify chemical composition and additives with the aim of obtaining a set of markers or compounds that will allow forensic scientists to identify fuel sources. The study was performed using petrol and diesel sold in the city of Lincoln (UK) during four seasons (winter, spring, summer, autumn).Diesel samples, representing eight different brands were analyzed by gas chromatography−mass spectrometry (GC−MS) and principal component analysis (PCA). From the GC–MS analytical results, MTBE and ETBE were identified as the additive more preferably added in super unleaded petrol samples that can be used to aid in separation and identification. In diesel, the distribution of FAME contents showed the effect of seasonal variation as these were found in all spring, summer and autumn samples, but not found in all winter ones. The selection of a reduced number of key fuel compounds and additives was also shown to be sufficient to achieve a high level of classification among the different fuel samples. Leave–one–out cross–validation was applied in order to validate the results.
Computational Analysis of new Degree-based descriptors of oxide networks
Authors: Hussain Zafar , Munir Mobeen , Bilal Muhammad , Ameer Alam , Rafique Shazia , Kang Shin Min
Published: April 2019

Oxide networks have diverse applications in the polymer and pharmaceutical industries. Polynomials and degree-based topological indices have tendencies to correlate properties of molecular graphs. In this article, we formulate the closed forms of Zagreb and forgotten polynomials and topological indices such as Hyper-Zagreb index, first and second multiple Zagreb indices, forgotten index, Albert index, Bell index, IRM(G) of oxide networks. We also compute the F-index of complement of oxide networks, F-coindex of G and F-coindex of complement of oxide networks. We put graphical analysis of each index with respect to the parameter involved in each case.
Eigenvalue Problems for Exponential-Type Kernels
Authors: Cai Difeng , Vassilevski Panayot S.
Published: April 2019

We study approximations of eigenvalue problems for integral operators associated with kernel functions of exponential type. We show convergence rate

|

λ
k

-

λ

k
,
h

|

≤

C
k

⁢

h
2

{\lvert\lambda_{k}-\lambda_{k,h}\rvert\leq C_{k}h^{2}}

in the case of lowest order approximation for both Galerkin and Nyström methods, where h is the mesh size,

λ
k

{\lambda_{k}}

and

λ

k
,
h

{\lambda_{k,h}}

are the exact and approximate kth largest eigenvalues, respectively. We prove that the two methods are numerically equivalent in the sense that

|

λ

k
,
h

(
G
)

-

λ

k
,
h

(
N
)

|

≤

C
⁢

h
2

{|\lambda^{(G)}_{k,h}-\lambda^{(N)}_{k,h}|\leq Ch^{2}}

, where

λ

k
,
h

(
G
)

{\lambda^{(G)}_{k,h}}

and

λ

k
,
h

(
N
)

{\lambda^{(N)}_{k,h}}

denote the kth largest eigenvalues computed by Galerkin and Nyström methods, respectively, and C is a eigenvalue independent constant. The theoretical results are accompanied by a series of numerical experiments.
Superconvergent DPG Methods for Second-Order Elliptic Problems
Authors: Führer Thomas
Published: April 2019

We consider DPG methods with optimal test functions and broken test spaces based on ultra-weak formulations of general
second-order elliptic problems.
Under some assumptions on the regularity of solutions of the model problem and its adjoint, superconvergence for the
scalar field variable is achieved by either increasing the polynomial degree in the corresponding approximation space by
one or by a local postprocessing.
We provide a uniform analysis that allows the treatment of different test norms.
Particularly, we show that in the presence of convection only the quasi-optimal test norm leads to higher convergence
rates, whereas other norms considered do not.
Moreover, we also prove that our DPG method delivers the best

L
2

{L^{2}}

approximation of the scalar field variable
up to higher-order terms, which is the first theoretical explanation of an observation made previously by different authors.
Numerical studies that support our theoretical findings are presented.
Explaining Brexit: How the City of London came to be Regulated by the European Union
Authors: Vaubel Roland
Published: April 2019

Qualified majority voting on financial market regulation was made possible by the European Court of Justice changing the meaning of the term “internal market” from “free movement of goods, services, persons and capital” to “conditions of competition which are not distorted”.
Formality properties of finitely generated groups and Lie algebras
Authors: Suciu Alexander I. , Wang He
Published: April 2019

We explore the graded-formality and filtered-formality properties of finitely generated groups by studying the various Lie algebras over a field of characteristic 0 attached to such groups, including the Malcev Lie algebra, the associated graded Lie algebra, the holonomy Lie algebra, and the Chen Lie algebra. We explain how these notions behave with respect to split injections, coproducts, direct products, as well as field extensions, and how they are inherited by solvable and nilpotent quotients. A key tool in this analysis is the 1-minimal model of the group, and the way this model relates to the aforementioned Lie algebras. We illustrate our approach with examples drawn from a variety of group-theoretic and topological contexts, such as finitely generated torsion-free nilpotent groups, link groups, and fundamental groups of Seifert fibered manifolds.
Conjugacy search problem and the Andrews–Curtis conjecture
Authors: Panteleev Dmitry , Ushakov Alexander
Published: April 2019

We develop new computational methods for studying potential counterexamples to the Andrews–Curtis conjecture, in particular, Akbulut–Kurby examples{\operatorname{AK}(n)}. We devise a number of algorithms in an attempt to disprove the most interesting counterexample{\operatorname{AK}(3)}. That includes an efficient implementation of the folding procedure for pseudo-conjugacy graphs, based on the original modification of a classic disjoint-set data structure. To improve metric properties of the search space (the set of balanced presentations of the trivial group), we introduce a new transformation, called an ACM-move, that generalizes the original Andrews–Curtis transformations and discuss details of a practical implementation. To reduce growth of the search space, we introduce a strong equivalence relation on balanced presentations and study the space modulo automorphisms of the underlying free group. We prove that automorphism moves can be applied to Akbulut–Kurby presentations. The improved technique allows us to enumerate balanced presentations AC-equivalent to{\operatorname{AK}(3)}with relations of lengths up to 20 (previous record was 17).
No Certainty and No Justice: The Counterintuitive Effects of Enforcing “No Oral Modification Clauses”
Authors: Tayar Joshua
Published: April 2019

The legal effect of the “No Oral Modification clause” (“NOM clause”) has been described by the UK Supreme Court as a “truly fundamental issue in the law of contract”. Courts in Australia, common law Canada, and many US states had held that the NOM clause, which prescribes that an agreement may not be amended save in writing, is unenforceable. However, in a recent decision, the UK Supreme Court unanimously held that it is enforceable. This Essay seeks to demonstrate that a uniform policy of non-enforcement of the NOM clause is more consistent with the basic principles of contract law and will likely yield greater certainty and justice in the long run.
An example of a hereditarily normal topologically finite space, which is topologically infinite relative to the class of all its proper F
σ-subspaces
Authors: Tsereteli Ivane
Published: April 2019

A (Hausdorf) hereditarily normal (not perfectly normal) space X is constructed, which has the following properties: (a) there exists a proper open subspace of X which is homeomorphic to the whole X (i.e., the space X is topologically infinite); (b) the space is homeomorphic to none of its proper

F
σ

{F_{\sigma}}

-subspaces (i.e., the space X is topologically finite relative to the class of all its proper

F
σ

{F_{\sigma}}

-subspaces).
Action theory of alternative algebras
Authors: Casas José Manuel , Datuashvili Tamar , Ladra Manuel
Published: April 2019

We present the category of alternative algebras as a category of interest.
This kind of approach enables us to describe derived actions in this category, study their properties and construct a universal strict general actor of any alternative algebra.
We apply the results obtained in this direction to investigate the problem of the existence of an actor in the category of alternative algebras.
On the construction of a covering map
Authors: Saneblidze Samson
Published: April 2019

Let

Y
=

|
X
|

{Y=\lvert X\rvert}

be the geometric realization of a path-connected simplicial set X, and let

G
=

π
1

⁢

(
X
)

{G=\pi_{1}(X)}

be the fundamental group.
Given a subgroup

H
⊂
G

{H\subset G}

, let

G
/
H

{G/H}

be the set of cosets.
Using the combinatorial model

𝛀
⁢
X

→

𝐏
⁢
X

→
X

{\boldsymbol{\Omega}X\to\mathbf{P}X\to X}

of the path fibration

Ω
⁢
Y

→

P
⁢
Y

→
Y

{{\Omega}Y\to{P}Y\to Y}

and a canonical action

μ
:

𝛀
⁢
X

×
G

/
H

→

G
/
H

{\mu\colon\boldsymbol{\Omega}X\times G/H\to G/H}

, we construct a covering map

G
/
H

→

Y
H

→
Y

{G/H\to Y_{H}\to Y}

as the geometric realization of the associated short sequence

G
/
H

→

𝐏
⁢
X

×
μ

G

/
H

→
X

{G/H\to\mathbf{P}X\times_{\mu}G/H\to X}

.
This construction, in particular, does not use the existence of a maximal tree in X.
For a 2-dimensional X and

H
=

{
1
}

{H=\{1\}}

, it can also be viewed as a simplicial approximation of a Cayley 2-complex of G.
Characterization of enzyme-resistant xylooligosaccharides extracted from hardwood chips by pre-hydrolysis and further depolymerized by enzymatic treatment
Authors: Guigon Valentin , Chirat Christine , Fort Laure , Lachenal Dominique
Published: April 2019

Xylose-rich solutions were produced by applying water pre-hydrolysis on mixed hardwood chips followed by an enzymatic treatment of the filtrate. The liquid phase obtained after water pre-hydrolysis contained xylose and xylans as the major components as well as other hemicelluloses and monosaccharides, acetic acid, and some degradation products of the monosaccharides [furfural, 5-(hydroxymethyl)furfural]. This hydrolysate underwent a two-step enzymatic treatment successively with endo-1,4-β-xylanase and 1,4-β-xylosidase to specifically depolymerize xylans into xylose without producing monosaccharides from the other oligosaccharides. After this treatment, 20.5% of the xylose units remained as oligomers. Matrix-assisted laser desorption ionization time-of-flight (MALDI-ToF) mass spectrometry was applied after each step of the treatment to approach the structure of hemicellulose oligomers, to follow their depolymerization and to understand the reason for the resistance of some of them to enzymatic hydrolysis. It was found that highly acetylated xylans and/or xylans still substituted with 4-O-methylglucuronic groups were particularly resistant to this treatment.