bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Electrophysical Properties of "Surkhon-104" Grade Cotton Fibers Alloyed with \(KMnO_4\)
Authors: Urokovna Umarova Saida
Published: September 2024

In this article, the physical properties of cotton fibers sort of "Surkhon-104" with thermal treatment were studied. The main results of the research are as follows. The electrophysical and photoelectrical properties of cotton fibers doped with KMnO4 were studied. The research was carried out in the temperature range of 300-360 K and voltage in the range of 0-100 V. Temperature dependence of electrical conductivity of cotton fibers was studied. It was proved that the current flowing from all samples prepared as a research object obeys Ohm's law. It was found that the photoconductivity caused by ultraviolet and visible light in the cotton fibers sample is mainly related to the formation of inter-zone electron-hole pairs. it was found that the electrical conductivity increased significantly due to the photogeneration of charge carriers. The long-term relaxation of photoconductivity was determined, which is related to the localization of electrons to Et2=Ec-1,5 eV levels.
COPING WITH FOURTH INDUSTRIAL REVOLUTION CHALLENGES: LEADERSHIP COMPETENCIES IN THE AIRLINE INDUSTRY
Authors: Garcia Edmond Paolo
Published: September 2024

This study aimed to identify leadership competencies crucial for navigating the Fourth Industrial Revolution in the airline sector, utilizing a mixed-method approach, specifically an explanatory sequential design. Data from 210 employees underwent analysis using des­criptive and inferential statistics, predictive analytics, and bootstrapping methods. Findings indicated that while age and education had no bearing on leadership competencies, gender, tenure, and positions displayed variations, indicating competency enhancements regardless of demographics. Furthermore, all competencies studied significantly predicted overall suc­cess, with some explicitly influencing challenges associated with the Fourth Industrial Re­vo­lution. A proposed leadership development framework addressed the findings precisely challenges, with practical implications focusing on driving success and sustainability in the airline industry.
INTERPLAY OF NOSTALGIA AND MEMORABLE EXPERIENCES: A STUDY ON APPAREL
Authors: Albores Alberto Borbolla , La Cruz Salomón Domínguez , Reyes-Mercado Pável
Published: September 2024

This study analyzed the relationship between nostalgia and memorable experiences on con­sumer purchase intention. While nostalgia was well-researched for Generation X and Y, there was a lack of understanding of how nostalgia influenced Generation Z brands and consumption pre­ferences. Nostalgia marketing has been popular for several years, and there was literature on pro­duct and service categories, such as movie remakes, band reunions, candy, and brands that have completed their life cycle and could be re-released to the market by appealing to consumers nos­tal­gia. It used a sample of 135 observations and sneakers stimuli advertising with nostalgic com­ponents. Results showed that nostalgia affected purchase intention directly and the retrieval of memorable experiences of using the apparel product. However, it did not translate to purchase intention. The results helped marketers identify courses of action to create effective commu­ni­ca­tion that triggers consumers' purchase intention who did not require product development.
PERSONAL KNOWLEDGE MANAGEMENT AND EMPLOYEE PERFORMANCE NEXUS WITH THRIVING AT WORK AS A MEDIATING FACTOR IN A PUBLIC ORGANIZATION CONTEXT
Authors: Ononye Uzoma Heman , Ikechukwu Madumezia
Published: September 2024

This study examined the relationship between personal knowledge management and employee performance by accounting for the mediational effect of thriving at work. The study used a cross-sectional survey to obtain data from 204 academic staff randomly sampled from state-owned uni­versities in Delta State, Nigeria. The partial least squares method was applied to treat and analyze the data collected with the help of SmartPLS 4 software. The analysis revealed that knowledge sharing, creation, and acquisition were positively and significantly related to employee performance. Furthermore, the mediation role of thriving was also confirmed. In conclusion, personal knowledge management activities comprising knowledge sharing, knowledge creation, and knowledge acqui­sition, directly and indirectly, affected employee performance through thriving at work. The study recommended that public managers should incentivize and support the personalization of knowledge management activities across organizational levels, as it benefited thriving at work and employee performance, especially its adaptive aspects. Furthermore, personal knowledge management and thriving at work were driven or guided by knowledge, making organizations need to curate inter­ven­tions to improve knowledge.
Penerapan Konsep Circular Economy melalui Pelatihan Pengolahan Limbah Minyak Jelantah sebagai Upaya Mengurangi Pencemaran Lingkungan
Authors: Rahmiati Filda , Hanafiah Hally , Jokhu Jean Richard , Daniela Lerissa , Siregar Jonathan Lampatar , Santosa Setyarini , Mangkurat R. Stevanus Bayu
Published: September 2024

Penerapan teori Circular Economy dalam pembuatan pelatihan pembuatan sabun dari minyak jelantah ini dilaksanakan untuk menganalisis konsep Circular Economypada UMKM (Usaha Mikro, Kecil, dan Menengah) di Cikarang. Tujuan utama dari pelatihan ini adalah untuk mengimplementasi-kan teori konsep Circular Economy pada pelaku UMKM. Pada aktifitas kegiatan ilmiah ini para pelaku UMKM diberikan pengenalan akan Circular Economy melalui pengolahan limbah minyak jelantah menjadi produk yang bernilai ekonomis dan ramah lingkungan, yaitu sabun. Aktifitas ini mencakup aspek-aspek penting dari teknik pembuatan sabun, penggunaan bahan tambahan yang aman, dan manfaat lingkungan dari pemanfaatan kembali minyak jelantah yang biasanya dibuang. Hasil dari aktifitas ini peserta mendapatkan pengetahuan praktis dan pengalaman langsung dalam mengubah limbah menjadi produk yang dapat dipasarkan dan dari kegiatan ini pelaku UMKM menunjukkan peningkatan signifikan dalam keterampilan dan pemahaman peserta mengenai pengolahan limbah. Pelaku berhasil memproduksi sabun berkualitas tinggi yang memiliki potensi untuk didistribusikan secara komersial. Inisiatif ini tidak hanya membantu mengurangi pencemaran lingkungan tetapi juga menyediakan sumber pendapatan tambahan bagi UMKM di Cikarang. Keberhasilan pelatihan ini menekankan pentingnya mengintegrasikan praktik Circular Economy dalam bisnis lokal, mendorong pembangunan berkelanjutan, dan mempromosikan pengelolaan lingkungan. Dengan memanfaatkan bahan limbah secara efektif, UMKM dapat berkontribusi pada ekonomi yang lebih berkelanjutan dan menciptakan dampak positif bagi lingkungan dan stabilitas keuangan.
Peningkatan Keterampilan Teknologi Informasi dan Komunikasi untuk Siswa-Siswi Sekolah Luar Biasa Sidoarjo
Authors: Rahmawati Aulia Afniar , Arkansyah Mochammad , Murtadlo Athok
Published: September 2024

Pendidikan Teknologi dan Informasi merupakan kebutuhan penting pada era modern saat ini yang mana siswa-siswi dituntut untuk mempelajari bidang teknologi sebagai penguatan masa depan. Kegiatan peningkatan keterampilan teknologi informasi dan komunikasi untuk siswa siswi sekolah luar biasa ini mengajarkan untuk memahami tools pada computer. Tools perangkat lunak sangat penting untuk memfasilitasi berbagai tugas dan aktivitas yang dilakukan komputer. sistem operasi seperti Windows yang membantu menjalankan tugas dasar komputer hingga aplikasi produktivitas seperti Microsoft Office, Google Workspace, dan sebagainya. Selain itu keterampilan untuk membantu dalam produksi desain grafis dan multimedia, serta pengolahan data dan kolaborasi.  Selain itu, program pengolahan gambar seperti Photoshop, Illustrator dan canva memungkinkan pengguna membuat karya seni digital yang sangat rinci. Secara keseluruhan, alat perangkat lunak ini sangat penting untuk meningkatkan produktivitas dan kreatifitas pengguna komputer kontemporer. Tidak hanya perangkat lunak namun keterampilan perangkat keras juga dibutuhkan dalam peningkatan IT seperti memahami monitor, cpu, keyboard dan sebagainya. Motivasi dari kegiatan ini adalah ingin memberikan peningkatan keterampilan teknologi informasi dan komunikasi dengan memberikan praktik secara ofline untuk siswa -siswi Sekolah Luar biasa (SLB) tingkat SMA agar mereka mendapatkan bekal skill mengoprasikan komputer. Tahapan program pengabdian masyarakat ini adalah melakukan perencanaan yang mana Lembaga Penelitian dan Pengabdian Masyarakat (LPPM) Stikosa-AWS berkerjasama dengan BPSDMP Kominfo Surabaya terkait fasilitas – fasilitas yang diberikan siswa-siswi SLB, selanjutnya pemilihan instruktur dan asisten instruktur dalam pengajarannya, kemudian pelaksanaan kegiatan serta evaluasi. Hasil dari kegiatan pengabdian masyarakat dapat diketahui dari respon guru-guru Sekolah Luar Biasa Sidoarjo mengapresiasi Stikosa-AWS dan BPSDMP Kominfo Surabaya dengan memberikan fasilitas serta pelatihan untuk siswa-siswinya. Kemudian peningkatan keterampilan teknologi informasi dan komunikasi siswa -siwi menjandi meningkat dari hasil proyek selama pembelajaran sehingga mereka dapat mengoprasikan komputer dengan baik.
Membangun Entrepreneur Muda di Kalangan Siswa Melalui Pelatihan Ideasi dan Pitching
Authors: Yusup Adi Kurniawan , Josephine Cherry , Limanto Kent Avila , Dewi Theresia Dinda Kusuma , Putri Kimartha
Published: September 2024

Dalam menghadapi perubahan yang cepat di era teknologi yang semakin ketat, pengembangan keterampilan kewirausahaan menjadi suatu keharusan. Era digitalisasi membawa peluang baru dan tantangan kompleks dalam dunia bisnis dimana hal tersebut menuntut inovasi sebagai kunci untuk mengatasi masalah yang muncul. Oleh karena itu, keterampilan kewirausahaan menjadi semakin penting, bukan hanya sebagai tambahan, melainkan sebagai kebutuhan esensial bagi individu untuk berhasil beradaptasi dan berkembang dalam lingkungan bisnis yang dinamis. Acara pengabdian masyarakat ini bertujuan untuk meningkatkan pemahaman dan keterampilan kewirausahaan siswa di Sekolah Citra Berkat Surabaya. Pelatihan ini membahas tentang proses ideasi dan prototyping yang memungkinkan siswa untuk mengembangkan ide bisnis inovatif. Metode pelaksanaan acara mencakup sesi edukasi, diskusi kelompok dengan bimbingan mentor, serta presentasi ide bisnis kepada tim dosen sebagai calon investor. Melalui kegiatan ini, siswa tidak hanya diberikan pemahaman teoritis tentang kewirausahaan, tetapi juga diberi kesempatan untuk mengaplikasikan pengetahuan tersebut dalam situasi nyata. Mereka diajak untuk merancang dan mengembangkan ide bisnis mereka sendiri, dengan dukungan dan bimbingan dari mentor yang berpengalaman. Proses presentasi ide bisnis kepada tim dosen sebagai calon investor menjadi kesempatan bagi siswa untuk mengasah keterampilan komunikasi mereka, serta menerima umpan balik yang konstruktif dari para profesional dalam bidangnya. Hasil positif ini menegaskan pentingnya pengembangan keterampilan kewira­usahaan di tingkat pendidikan menengah sebagai bekal siswa menghadapi tantangan bisnis di masa depan.
Pelatihan dan Pendampingan Analisa Kelayakan Usaha Budidaya Ikan Lele di Bhakti Farm Ciledug
Authors: Rizky Farid Al , Riyadi Sugeng
Published: September 2024

Indonesia sebagai negara kepulauan terbesar di dunia memiliki potensi yang besar dalam sektor perikanan, khususnya dalam budidaya ikan lele. Bhakti Farm, sebuah usaha budidaya pembesaran ikan lele yang telah berdiri sejak tahun 2019 mengalami tantangan dalam pengelolaan keuangan dan analisis kelayakan usaha yang menghambat pertumbuhan usahanya. Kegiatan pengabdian kepada masyarakat ini bertujuan untuk meningkatkan pemahaman dan keterampilan pemilik usaha dalam melakukan analisis kelayakan usaha yang meliputi analisis biaya, analisis penerimaan dan analisis kelayakan usaha. Metode yang digunakan dibagi menjadi tiga tahap, yaitu persiapan, pelaksanaan serta monitoring dan evaluasi. Pada tahapan persiapan, dilaksanakan survei dan wawancara dengan pemilik usaha untuk mengidentifikasi kebutuhan bisnisnya secara spesifik. Terutama dalam pencatatan dan analisis keuangan yang belum diterapkan dengan baik. Tahap pelaksanaan dilakukan dengan memberikan materi teoritis dan pendampingan praktis secara langsung yang meliputi analisis biaya, analisis penerimaan serta analisis kelayakan usaha. Tahap monitoring dan evaluasi dilakukan untuk memastikan pemilik dapat memahami konsep-konsep dasar analisa kelayakan usaha. Hasil dari kegiatan ini adalah pemilik usaha mampu menerapkan konsep dasar analisa usaha terutama dalam membuat laporan keuangan yang lebih akurat menggunakan template yang diberikan pada tahapan pelaksanaan. Selain itu, pemilik usaha mampu menghitung serta menganalisa data nyata dengan menggunakan catatan nya per bulan Januari 2024. Sehingga pemilik dapat melakukan perhitungan analisis biaya yang terdiri dari biaya tetap dan biaya tidak tetap sebesar Rp. 58.581.400 dengan total penerimaan sebesar RP. 86.058.000 maka pendapatan yang diperoleh sebesarRp. 27.476.600. Terakhir, pemilik dapat mengetahui apakah usaha yang dijalankan sudah efisien atau belum, yaitu dengan analisis R/C ratio. Hasil perhitungan diperoleh nilai R/C ratio sebesar 1,46 artinya, dapat disimpulkan usaha budidaya ikan lele yang dijalankan sudah efisien.
Inclusive Education in Yemen: Policies, Practices, and Barriers
Authors: Basha Tameem Yahya Ali , Al-Sana'ani Abdo Saeed , Al-Mekhlafi Sadeq Abdo Saif
Published: September 2024

Despite having signed most international conventions and enacted numerous national legislations related to inclusive education (IE), the Yemen's educational system still faces many problems and barriers that hinder the success of IE programs. This study aims to investigate policies, practices, and barriers of IE for students with disabilities (SWDs) and recommend some measures to improve the current scenario of IE in Yemen. The researchers analyzed relevant national policy documents and academic literature as well as conducted a survey of 14 headmasters and 176 teachers at 14 schools that implement IE. The results revealed that only a limited number of SWDs were attending general schools, which mostly used the resource room model to implement inclusion programs. However, these schools face many problems that undermine the practicing of IE, including lack of adapted curriculum, individualized education plans (IEPs), special educators, assessment tools, and related services. Moreover, the teachers reported financial barriers to implement inclusion programs as well as barriers related to pre-inclusion planning, curriculum, teachers, physical environment, diagnosis and admission, and students with disabilities themselves. This article concludes with some recommendations to improve the current situation of IE in Yemen.
Habilidades Sociais e Sentido da Vida: Revisão Sistemática
Authors: C.T. Silveira Deliani , S. Elias Luciana Carla
Published: September 2024

Social skills, as well as having a meaning in life, are important factors throughout human development; the fi rst focuses on the importance of learning, social context and positive results for those involved insocial relationships and; the second appeals to consciousness for the perception of the meaning of life, in any situation, as well as for its search. The objective was to review the scientifi c literature regarding prevention and promotion programs aimed at adolescents in a school context, focusing on social skills and/or the meaning of life. As for the specifi c objectives, they were to verify format, time, applicator and eff ects. To this end, the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) protocol was used, searching articles indexed in the Jstor, PsycInfo, Scopus, ERIC and Web of Science databases in the last 10 years, using the descriptors “logotherapy”, “meaning in life”, “social skills”, “school”, “adolescent”, “promotion”, “prevention” and “intervention”. Were found 23 articles, of which 20 programs focused on social skills, two addressed the meaning in life, and one both themes. The studies pointed to programs with many levels, of complexity, having diff erent methodological designs, applied in diff erents school contexts to respond to the objectives outlined. It is concluded that programs that work on both themes (social skills and meaning in life) are scarce in school contexts .Keywords:Adolescents, interventions, prevention, promotion, school healthcare
Small protein domains fold inside the ribosome exit tunnel
Authors: Marino Jacopo , von Heijne Gunnar , Beckmann Roland
Published: February 2016

Cotranslational folding of small protein domains within the ribosome exit tunnel may be an important cellular strategy to avoid protein misfolding. However, the pathway of cotranslational folding has so far been described only for a few proteins, and therefore, it is unclear whether folding in the ribosome exit tunnel is a common feature for small protein domains. Here, we have analyzed nine small protein domains and determined at which point during translation their folding generates sufficient force on the nascent chain to release translational arrest by the SecM arrest peptide, both in vitro and in live E. coli cells. We find that all nine protein domains initiate folding while still located well within the ribosome exit tunnel.
A common ‘aggregation‐prone’ interface possibly participates in the self‐assembly of human zona pellucida proteins
Authors: Louros Nikolaos N. , Chrysina Evangelia D. , Baltatzis Georgios E. , Patsouris Efstratios S. , Hamodrakas Stavros J. , Iconomidou Vassiliki A.
Published: February 2016

Human zona pellucida (ZP) is composed of four glycoproteins, namely ZP1, ZP2, ZP3 and ZP4. ZP proteins form heterodimers, which are incorporated into filaments through a common bipartite polymerizing component, designated as the ZP domain. The latter is composed of two individually folded subdomains, named ZP‐N and ZP‐C. Here, we have synthesized six ‘aggregation‐prone’ peptides, corresponding to a common interface of human ZP2, ZP3 and ZP4. Experimental results utilizing electron microscopy, X‐ray diffraction, ATR FT‐IR spectroscopy and polarizing microscopy indicate that these peptides self‐assemble forming fibrils with distinct amyloid‐like features. Finally, by performing detailed modeling and docking, we attempt to shed some light in the self‐assembly mechanism of human ZP proteins.
Molecular mechanism of constitutively active Rab11A was revealed by crystal structure of Rab11A S20V
Authors: Choi Jae Young , Shin Young‐Cheul , Yoon Jong Hwan , Kim Chang Min , Lee Jun Hyuck , Jeon Ju‐Hong , Park Hyun Ho
Published: February 2016

Rab11A is a small GTP‐binding protein involved in the regulation of vesicle trafficking during recycling of endosomes. Substitution of S20 to V (S20V) at Rab11A inhibits the GTP hydrolysis activity of Rab11A. This mutation is known to be constitutively in an active form. Here, we report the crystal structure of the human Rab11A S20V mutant form complexed with GTP at a resolution of 2.4 Å. Without adding any substrate, Rab11A contained non‐hydrolyzed natural substrate GTP in the nucleotide binding pocket with Mg2+. In our observations, substituted V20 of Rab11A was found to interfere with proper localization of the water molecule, which mediated GTP hydrolysis, resulting in GTP being locked in an active form of Rab11A S20V.
Hydrothermal venting and mineralization in the crater of Kick'em Jenny submarine volcano, Grenada (Lesser Antilles)
Authors: Carey Steven , Olsen Rene , Bell Katherine L.C. , Ballard Robert , Dondin Frederic , Roman Chris , Smart Clara , Lilley Marvin , Lupton John , Seibel Brad , Cornell Winton , Moyer Craig
Published: February 2016

Kick'em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (∼70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine‐grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound‐like vents at a maximum temperature of 180°C. The gas consists of 93–96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5–35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish‐yellow bacteria with the production of Fe‐oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high‐resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature.
High‐resolution modeling of the cusp density anomaly: Response to particle and Joule heating under typical conditions
Authors: Brinkman Douglas G. , Walterscheid Richard L. , Clemmons James H. , Hecht James. H.
Published: February 2016

An established high‐resolution dynamical model is employed to understand the behavior of the thermosphere beneath the Earth's magnetic cusps, with emphasis on the factors contributing to the density structures observed by the CHAMP and Streak satellite missions. In contrast to previous modeling efforts, this approach combines first principles dynamical modeling with the high spatial resolution needed to describe accurately mesoscale features such as the cusp. The resulting density structure is shown to be consistent with observations, including regions of both enhanced and diminished neutral density along the satellite track. This agreement is shown to be the result of a straightforward application of input conditions commonly found in the cusp rather than exaggerated or extreme conditions. It is found that the magnitude of the density change is sensitive to the width of the cusp region and that models that can resolve widths on the order of 2° of latitude are required to predict density variations that are consistent with the observations.
Fluid‐faulting evolution in high definition: Connecting fault structure and frequency‐magnitude variations during the 2014 Long Valley Caldera, California, earthquake swarm
Authors: Shelly David R. , Ellsworth William L. , Hill David P.
Published: February 2016

An extended earthquake swarm occurred beneath southeastern Long Valley Caldera between May and November 2014, culminating in three magnitude 3.5 earthquakes and 1145 cataloged events on 26 September alone. The swarm produced the most prolific seismicity in the caldera since a major unrest episode in 1997–1998. To gain insight into the physics controlling swarm evolution, we used large‐scale cross correlation between waveforms of cataloged earthquakes and continuous data, producing precise locations for 8494 events, more than 2.5 times the routine catalog. We also estimated magnitudes for 18,634 events (~5.5 times the routine catalog), using a principal component fit to measure waveform amplitudes relative to cataloged events. This expanded and relocated catalog reveals multiple episodes of pronounced hypocenter expansion and migration on a collection of neighboring faults. Given the rapid migration and alignment of hypocenters on narrow faults, we infer that activity was initiated and sustained by an evolving fluid pressure transient with a low‐viscosity fluid, likely composed primarily of water and CO2exsolved from underlying magma. Although both updip and downdip migration were observed within the swarm, downdip activity ceased shortly after activation, while updip activity persisted for weeks at moderate levels. Strongly migrating, single‐fault episodes within the larger swarm exhibited a higher proportion of larger earthquakes (lower Gutenberg‐Richterbvalue), which may have been facilitated by fluid pressure confined in two dimensions within the fault zone. In contrast, the later swarm activity occurred on an increasingly diffuse collection of smaller faults, with a much higherbvalue.
Locally driven interannual variability of near‐surface pH and ΩA in the Strait of Georgia
Authors: Moore‐Maley Ben L. , Allen Susan E. , Ianson Debby
Published: February 2016

Declines in mean ocean pH and aragonite saturation state (ΩA) driven by anthropogenic CO2 emissions have raised concerns regarding the trends of pH and ΩA in estuaries. Low pH and ΩA can be harmful to a variety of marine organisms, especially those with calcium carbonate shells, and so may threaten the productive ecosystems and commercial fisheries found in many estuarine environments. The Strait of Georgia is a large, temperate, productive estuarine system with numerous wild and aquaculture shellfish and finfish populations. We determine the seasonality and variability of near‐surface pH and ΩA in the Strait using a one‐dimensional, biophysical, mixing layer model. We further evaluate the sensitivity of these quantities to local wind, freshwater, and cloud forcing by running the model over a wide range of scenarios using 12 years of observations. Near‐surface pH and ΩA demonstrate strong seasonal cycles characterized by low pH, aragonite‐undersaturated waters in winter and high pH, aragonite‐supersaturated waters in summer. The aragonite saturation horizon generally lies at ∼20 m depth except in winter and during strong Fraser River freshets when it shoals to the surface. Periods of strong interannual variability in pH and aragonite saturation horizon depth arise in spring and summer. We determine that at different times of year, each of wind speed, freshwater flux, and cloud fraction are the dominant drivers of this variability. These results establish the mechanisms behind the emerging observations of highly variable near‐surface carbonate chemistry in the Strait.
Seasonal heat and freshwater cycles in the Arctic Ocean in CMIP5 coupled models
Authors: Ding Yanni , Carton James A. , Chepurin Gennady A. , Steele Michael , Hakkinen Sirpa
Published: February 2016

This study examines the processes governing the seasonal response of the Arctic Ocean and sea ice to surface forcings as they appear in historical simulations of 14 Coupled Model Intercomparison Project Phase 5 coupled climate models. In both models and observations, the seasonal heat budget is dominated by a local balance between net surface heating and storage in the heat content of the ocean and in melting/freezing of sea ice. Observations suggest ocean heat storage is more important than sea ice melt, while in most of these models, sea ice melt dominates. Seasonal horizontal heat flux divergence driven by the seasonal cycle of volume transport is only important locally. In models and observations, the dominant terms in the basin‐average seasonal freshwater budget are the storages of freshwater between the ocean and sea ice, and the exchange between the two. The largest external source term is continental discharge in early summer, which is an order of magnitude smaller. The appearance of sea ice (extent and volume) and also ocean stratification in both the heat and freshwater budgets provides two links between the budgets and provides two mechanisms for feedback. One consequence of such an interaction is the fact that models with strong/weak seasonal surface heating also have strong/weak seasonal haline and temperature stratification.
Statistical downscaling and dynamical downscaling of regional climate in China: Present climate evaluations and future climate projections
Authors: Tang Jianping , Niu Xiaorui , Wang Shuyu , Gao Hongxia , Wang Xueyuan , Wu Jian
Published: February 2016

Statistical downscaling and dynamical downscaling are two approaches to generate high‐resolution regional climate models based on the large‐scale information from either reanalysis data or global climate models. In this study, these two downscaling methods are used to simulate the surface climate of China and compared. The Statistical Downscaling Model (SDSM) is cross validated and used to downscale the regional climate of China. Then, the downscaled historical climate of 1981–2000 and future climate of 2041–2060 are compared with that from the Weather Research and Forecasting (WRF) model driven by the European Center‐Hamburg atmosphere model and the Max Planck Institute Ocean Model (ECHAM5/MPI‐OM) and the L'Institut Pierre‐Simon Laplace Coupled Model, version 5, coupled with the Nucleus for European Modelling of the ocean, low resolution (IPSL‐CM5A‐LR). The SDSM can reproduce the surface temperature characteristics of the present climate in China, whereas the WRF tends to underestimate the surface temperature over most of China. Both the SDSM and WRF require further work to improve their ability to downscale precipitation. Both statistical and dynamical downscaling methods produce future surface temperatures for 2041–2060 that are markedly different from the historical climatology. However, the changes in projected precipitation differ between the two downscaling methods. Indeed, large uncertainties remain in terms of the direction and magnitude of future precipitation changes over China.
Auditory Processing
Authors: Portfors Christine V
Published: February 2016

Sound is encoded as action potential trains by the cochlea and transmitted along the eighth nerve into the cochlear nucleus. Central auditory processing exemplifies several general principles of sensory neuronal conduction and control. Information is processed in parallel, with subdivisions of the auditory pathway adapted for specialised feature extraction, and it is hierarchical. The temporal properties of sound mean that the preservation of timing information during auditory processing is of fundamental importance. Timing cues are especially important for encoding the horizontal position of a sound source. Interaural timing differences are encoded by brainstem nuclei with specialised neuronal features. Characteristics of the auditory system have also evolved to encode features present in social vocalisations. The complex interaction between excitation and inhibition in the auditory midbrain enables selective encoding of particular vocalisations by different populations of neurons. Thus, auditory processing has evolved such that behaviourally relevant sounds are efficiently encoded.

Key Concepts

The fundamental organising principle of the auditory system is tonotopy, which is a systematic representation of frequency that starts at the level of the basilar membrane.

The ascending auditory pathway is comprised of many nuclei that enable both parallel and serial information processing.

The inferior colliculus (the main auditory midbrain nucleus) is the main point of convergence of ascending and descending information.

Interaural timing differences are encoded in the medial superior olive (in mammals) and depend on coincidence detection, delay lines and specialised neuronal characteristics.

Interaural level differences are encoded in the lateral superior olive (in mammals) and depend on interactions of excitation and inhibition.

The barn owl is an exceptional animal that can precisely localise sound in the horizontal and vertical plane by using interaural timing and interaural level differences.

A fundamental function of the auditory system is to detect, discriminate and categorise complex sounds such as social vocalisations.

Neurons in the inferior colliculus are selective to vocalisations such that a unique neural representation occurs for different vocalisations.

The complex interplay between excitation and inhibition in the inferior colliculus results in heterogeneous responses to vocalisations.

The mouse auditory system has evolved to utilise cochlear distortions created by overlapping ultrasonic frequencies to encode social vocalisations that have spectral content much higher than the tuning properties of the neurons.
Algal Calcification and Silicification
Authors: Koester Julie , Brownlee Colin , Taylor Alison R
Published: February 2016

The algae represent major producers of calcium carbonate and silica among the world's biota. Calcification involves the precipitation of CaCO
3
from Ca
2+
and CO
3
2
−
ions. Algal calcification by coccolithophores may account for up to half of global oceanic CaCO
3
production. Silicification, the transformation of silicic acid into skeletal material, occurs in a few algal groups. The abundant diatoms represent the major silicifiers, playing a key role in marine silica cycling. Fossilised diatomaceous deposits have long been exploited for building and filling materials. Biomineralisation of calcium and silicon require homeostatic ion controls that are well characterised for Ca
2+
and H
+
in coccolithophores. Calcification occurs in an alkalinised vesicle, while silicification requires an acidic pH. Research on silicification remains focused upon cell wall development. Initiation and development of structures that are mineralised intracellularly requires initiation and regulation by organic components within the vesicles. Low‐temperature, low‐pressure biogenic formation of silica and calcite has potential for biotechnological application in novel industrial processes.

Key Concepts

Organisms across the tree of life are capable of biomineralisation.

Understanding the process of biomineralisation is required to interpret the information contained in biomineral geochemical proxies.

Mechanisms of calcification and silicification include uptake of inorganic ions via protein transporters, intracellular sequestration of those ions and the association of crystal initiation with an organic matrix.

The maintenance of metabolic homeostasis, especially relative to proton flux, is linked to calcification, but less is known about the effect of silicification on homoeostasis.

The adaptive functions of mineralised cellular structures remain hypothetical and are open topics of research.

The biological mechanisms of crystal formation have widespread applications in nanotechnology.
Histocompatibility Antigen Complex of Man
Authors: Mehra Narinder K , Kaur Gurvinder
Published: February 2016

The histocompatibility antigens are cell surface glycoproteins expressed on nucleated cells whose major function is to bind peptides within the cell or from outside and present them at the cell surface for inspection by T cells of the immune system. These antigens are a part of the major histocompatibility complex (MHC), which exists in most vertebrate species and whose products were originally defined as the most crucial elements controlling graft rejection. Human MHC research has revealed human leucocyte antigen (HLA) to be the most polymorphic genetic system in the mammalian genome, and this unique diversity parallels the need for diverse peptide sites within the MHC to combat a fast‐evolving range of pathogens. Clinical screening of HLA polymorphism is now an important prophylactic biomarker system for various diseases and a useful tool for development of peptide‐based vaccination approaches.

Key Concepts

HLA is the most polymorphic component of the human genome. It is a part of the major histocompatibility complex that exists in many animal species.

The major function of HLA molecules is antigen presentation.

High degree of molecular diversity of classical HLA class I and II molecules is a reflection of their direct role as antigen‐presenting molecules against a wide range of pathogens.

The MHC region is characterised by strong linkage disequilibrium between its loci such that conserved ancestral haplotypes can be identified.

There are population‐based differences in allelic distribution of MHC molecules primarily due to historical human migration patterns and varying microbial pressures in different geographical regions.

An individual heterozygous at a particular HLA locus has an added advantage than homozygous as the two different HLA molecules can bind and present a large number of peptides.

The function of the ubiquitous HLA class I gene products (HLA‐A, HLA‐B and HLA‐C) is to present endogenous peptides to responding CD8+ T cells, whereas the class II coded molecules (HLA‐DR, HLA‐DQ and HLA‐DP) have restricted tissue distribution and process exogenous peptides for presentation to CD4+ helper T cells.

The antigen‐binding cleft of HLA class I molecules can bind peptides that are usually nonamers, whereas the HLA class II antigen‐binding cleft can bind longer peptides of 11–18 mers.

Polymorphisms in the MHC have been associated with disease susceptibility, varying rates of disease progression and drug‐induced hypersensitivities.

MHC matching is crucial in donor selection for haematopoietic stem cell and organ transplantation.
Aquaporins: Channels for the Molecule of Life
Authors: Hacke Uwe G , Laur Joan
Published: February 2016

Liquid water has unique properties that make it a universal solvent. Water is an essential component of almost all physiological and biochemical reactions; therefore, its presence is required everywhere within an organism. The circulatory systems of animals and the vascular system of plants move fluids over long distances. In the tallest trees, water moves across a height gradient of 100 m or more, thereby connecting roots and distant leaves. On a cellular and tissue level, water movement is facilitated by intrinsic membrane proteins called aquaporins. These water channels are found in all life forms. Aquaporins have been mostly studied in mammals and plants, where water channels play important physiological roles. This article gives an overview of the discovery, structure and regulation of aquaporins. Their roles in different life forms are discussed.

Key Concepts

Water can diffuse through the lipid bilayer, but without aquaporins flow across membranes is slow.

Aquaporins are integral membrane transport proteins, and they facilitate water movement in cells, tissues and entire organisms.

A single water channel allows the passive passage of more than one billion water molecules per second.

The aquaporin protein family is ancient, and aquaporins can be found in a wide range of organisms.

Aquaporins appear to play important physiological roles in mammals, plants and other organisms.
Evolution of Secondary Plant Metabolism
Authors: Wink Michael
Published: February 2016

The biosynthesis of secondary metabolites (SMs), which are important for the fitness of the plants as defence against herbivores and microbes and also as signal compounds to attract pollinators and fruit dispersers, occurs universally in higher plants and shows very high structural diversity. The evolution of SMs in higher plants rests on variation in the enzymatic manipulation of a relatively small number of primary precursors. Evidence is presented that at least some of the genes encoding key enzymes of biosynthesis probably have reached plants by ancient horizontal gene transfer (HGT), for example, from protobacteria or cyanobacteria which later became mitochondria and plastids. Another source of SMs can be ectomycorrhizal and endophytic fungi; they can directly provide plants with defence compounds or might have transferred their pathway genes into the genome of their host plants times ago.

Key Concepts

Plants have evolved secondary metabolites as bioactive substances as a measure to protect themselves against herbivores.

Secondary metabolites are part of the innate immune system of plants, used to defend themselves against bacteria, fungi and viruses.

Secondary metabolism is dynamic and can react in case of a herbivoral or microbial attack by activating prodrugs, by either increasing the concentration of existing SM or by inducing the synthesis of new SMs (phytoalexins).

Secondary metabolites occur in a broad diversity and functionality.

Secondary metabolites derive from primary metabolites using a limited number of key pathways. Functional diversity is gained by adding diverse combinations of reactive functional groups.

Terpenoids and phenolics are present in almost all plants, whereas alkaloids and other nitrogen‐containing SMs are more common in angiosperms.

Some groups of SMs occur in a few restricted plant genera only, which are often not related.

The patchy distribution can be due to convergent evolution of the corresponding pathways.

Alternatively, the genes for SM biosynthesis have been introduced into the plant genome by horizontal gene transfer from protobacteria (which became mitochondria) and cyanobacteria (which became chloroplast).

Some SMs are produced by endophytic fungi, which infect a limited number of often unrelated species. As a consequence, this can also lead to a patchy distribution of SMs.
Epidermis: Outer Cell Layer of the Plant
Authors: Glover Beverley J , Airoldi Chiara A , Moyroud Edwige
Published: February 2016

The epidermis is the protective outer layer of clonally related cells covering all plant organs. It is composed of a number of specialised cell types which differentiate from the basal epidermal cell in adaptively significant frequencies and patterns. The epidermis is unique in developing solely through anticlinal divisions, generating a sheet of cells overlying the rest of the plant. This sheet is connected physically and biochemically to the cell layers below, with information exchange occurring in both directions. The specialised cell types within the epidermis develop either through communication among themselves, or, in some cases, through communication also with the underlying cell layers. Brief descriptions of the molecular genetic control of trichomes, stomata, root hairs and petal conical‐papillate epidermal cells are provided here, along with a summary of the role of the cuticle in epidermal cell morphology and of the interplay between cuticle regulation and cell morphology.

Key Concepts

The plant epidermis is a single layer of clonally related cells.

Plant epidermis fulfils a basic protective function, but specialised cells within the epidermis have specific roles.

The seedling epidermis arises by isolation of the outer layer during embryogenesis. The aerial epidermis and the root epidermis originate later, in the shoot apical meristem and in the root apical meristem, respectively.

Stomatal guard cells allow gas exchange, and their patterning is controlled by cell‐lineage‐based developmental mechanisms.

Trichomes protect the plant from herbivores, and their patterning is controlled by cell–cell interactions.

Root hairs increase surface area for water and nutrient uptake, and are patterned according to positional signals.

The cuticle overlying the epidermis can contribute to epidermal cell shape and function.

There is interplay between the regulation of epidermal cell shape and the regulation of cuticle production.
Hybrid Incompatibility inDrosophila: An Updated Genetic and Evolutionary Analysis
Authors: Fontdevila Antonio
Published: February 2016

Negative interactions between independently evolved genes in two species are responsible of incompatibility of their hybrid, manifested by sterility and inviability. The heterogametic sex (XY males inDrosophila) is the most affected and the X chromosome has the largest effect on hybrid incompatibility (HI). These rules of speciation depend on the genetic architecture of HI. Albeit some speciation genes have a major effect, this architecture shows a complex polygenic structure of multiple interactions. HI genes are frequently associated to genetic factors that evolved selfishly by favouring their preferential transmission. Genetic analyses show signatures of positive selection in speciation genes that may favour the role of adaptive evolution. Whether these signatures are compatible with evolution of selfish factors – an idea that is gaining support – still remains a contentious issue. Finally, there is also a current upsurge of evidences in favour of the importance of genetic regulation in the evolution of hybrid incompatibilities.

Key Concepts

Species must maintain their identity by isolation mechanisms that prevent gene flow among them.

In sexual species, hybrid incompatibility, evidenced by sterility and/or inviability, is an isolation mechanism of great importance.

The negative interaction in the hybrid between at least two genes that each evolved independently in two species (the BDM model) has been proved by multiple studies.

Several genes of major effect (speciation genes) are highly implicated, albeit interacting with other genetic factors, in hybrid incompatibilities.

A complex architecture of many genes with multiple interactions among them underlies the hybrid incompatibility.

The heterogametic sex is generally more affected by the hybrid incompatibility through interactions between X‐linked recessive genes and partially dominant autosomal genes (the dominant theory).

When substituted in a foreign genome, the X chromosome has a larger effect than any autosomal substitution, due to the greater density of speciation genes in the X chromosome.

Many speciation genes show signatures of positive selection in their DNA, which suggests, but not always, adaptive evolution.

Some speciation genes are associated to genetic factors evolved by genetic conflict, for example, meiotic drive, suggesting that a kind of evolutionary arms race between drivers and suppressors underlies the evolution of hybrid incompatibility.

Recently, regulatory divergence rather than divergence in coding sequences is gaining support as a main actor in hybrid incompatibilities.
Regeneration of Organs and Appendages in Zebrafish: A Window into Underlying Control Mechanisms
Authors: Antos Christopher L , Knopf Franziska , Brand Michael
Published: February 2016

The ability to regenerate organs and appendages is not universal among animals. Humans have a rather limited capacity to regenerate after an injury, while other vertebrates such as the zebrafish are capable of regenerating many anatomical structures. It is unknown why different vertebrates have such differences in regenerative capacity, so studying animal models that do regenerate will allow us to know what is needed to regenerate. Zebrafish research is not only able to tell us what mechanisms are involved in regeneration, but it also shows us that there are different regeneration strategies: some use stem cells while other create progenitors from differentiated tissue cells. This article details how zebrafish uses and regulates either differentiated tissue cells or stem cells to regenerate. We focus on four structures – fin appendage, brain, spinal cord and heart – and describe how current cell and molecular discoveries from these regenerating fish structures contribute to our understanding of general principles of regenerative biology.

Key Concepts

The zebrafish is a remarkablein vivomodel to understand the stem/progenitor cell biology and molecular mechanisms involved in appendage and organ regeneration.

Studying how the zebrafish regenerates its fins, its nervous system and its heart will provide information on how endogenous cell populations (whether fully differentiated or stem cells) are activated and concertedly controlled to regenerate compound structures.

Different zebrafish tissues use different strategies to regenerate: some convert differentiated tissue cells to progenitor cells while other draw from stem cell pools.

Zebrafish appendages and hearts regenerate primarily from the residual differentiated tissues.

Zebrafish nervous tissue regenerates from resident stem cell populations.