bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of radiation in organizing convection in weak temperature gradient simulations
Authors: Sessions Sharon L. , Sentić Stipo , Herman Michael J. 
Published: February 2016

AbstractUsing a cloud system resolving model with the large scale parameterized by the weak temperature gradient approximation, we investigated the influence of interactive versus noninteractive radiation on the characteristics of convection and convective organization. The characteristics of convecting environments are insensitive to whether radiation is interactive compared to when it is not. This is not the case for nonconvecting environments; interactive radiative cooling profiles show strong cooling at the top of the boundary layer which induces a boundary layer circulation that ultimately exports moist entropy (or analogously moist static energy) from dry domains. This upgradient transport is associated with a negative gross moist stability, and it is analogous to boundary layer circulations in radiative convective equilibrium simulations of convective self‐aggregation. This only occurs when radiation cools interactively. Whether radiation is static or interactive also affects the existence of multiple equilibria‐steady states which either support precipitating convection or which remain completely dry depending on the initial moisture profile. Interactive radiation drastically increases the range of parameters which permit multiple equilibria compared to static radiation; this is consistent with the observation that self‐aggregation in radiative‐convective equilibrium simulations is more readily attained with interactive radiation. However, the existence of multiple equilibria in absence of interactive radiation suggests that other mechanisms may result in organization.
Vertebrate Neurogenesis: Cell Polarity
Authors: Zolessi Flavio R 
Published: February 2016

Abstract

Neurons originate from epithelial cells that, after proliferation and cell fate decisions, undergo a series of polarity transitions to achieve the differentiated state. The fate of neural progenitors depends on the interplay between cell cycle and neuroepithelial polarity by two main mechanisms: (1) asymmetric inheritance of cytoplasmic determinants, such as molecules of the apical adhesion complexes, and (2) interkinetic nuclear migration through gradients of signalling molecules such as Notch. Regarding cell fate, divisions can be symmetric or asymmetric. After a neuron is born, differentiation initiates with a downregulation of epithelial polarity, followed by cell detachment and migration, and the final acquisition of a neuronal morphology. All these transitions are based on extremely conserved molecular mechanisms, including the involvement of polarity protein complexes (such as the PAR3 complex) and small GTPases that mostly affect actin and microtubule dynamics. However, some important variations have been observed in different neuronal types and experimental conditions.

Key Concepts

Neurons are highly polarised cells that are generated from progenitors with a different kind of polarity: neuroepithelial cells.

The neuroepithelium is an embryonic tissue characterised by its pseudo‐stratified organisation, with a basal lamina, sub‐apical cadherin‐based adhesion complexes and an apical primary cilium.

The pseudo‐stratified organisation of the neuroepithelium is actively maintained by interkinetic nuclear migration, a process by which cell nuclei locate at different apicobasal positions, according to their stage in the cell cycle.

Interkinetic nuclear migration provides the neuroepithelium with the possibility of rapidly proliferating while maintaining a relatively reduced size in the embryo.

Neuroepithelial polarity and interkinetic nuclear migration favour the asymmetric distribution of signalling cues (including extracellular molecules and cytoplasmic determinants), which are essential for neurogenesis, neuronal migration and neuronal polarisation.

Neurons are post‐mitotic cells, which are born from a progenitor cell division that can be symmetric (generating two neurons) or asymmetric (generating one neuron and another progenitor cell).

After the last cell division close to the apical surface, neuroblasts must migrate to their final differentiation position, and this migration is also influenced by cell polarity cues.

Neuronal polarisation mechanisms have largely been studied using cell cultures, where neurons extend an axon after a period of radially symmetric, multipolar organisation.

In the living tissue neurons must not only polarise (form one axon and oppositely directed dendrites) but also orient properly (the axon and dendrite must be directed to the right orientation).

In vitro
, mechanisms of neuronal polarisation rely mostly on intrinsic signals, such as the asymmetric accumulation of the PAR3 complex;
in vivo
, however, these intrinsic molecules are modulated by extrinsic signals such as Laminin‐1 or N‐Cadherin.
Follicular Dendritic Cells (BLymphocyte Stimulating)
Authors: Wang Changna , Ollerton Matthew T , Burton Gregory F 
Published: February 2016

AbstractFollicular dendritic cells (FDCs) are found in all secondary lymphoid tissues, where they function as a repository of antigens to maintain long‐term IgG and IgE responses. Antigens are trapped and retained on FDCs in the form of immune complexes; and while most immune complexes require large quantities to induce an immune response, FDC‐trapped antigens are remarkably immunogenic and only a few picogram can induce microgram concentrations of a specific antibody. In addition to providing antigens, FDCs provide a number of additional signals (e.g. BAFF, IL‐6) that further contribute to antibody production. In addition to their contributions to immunity in health, FDCs are involved in some pathological situations including HIV/AIDS (human immunodeficiency virus/acquired immune deficiency syndrome), sarcoma/lymphoma, prion‐mediated transmissible spongiform encephalopathies (e.g. Creutzfeldt–Jakob) and Castleman disease. A further understanding of FDCs and their functions in both health and disease may aid our ability to better regulate immunity and ameliorate some disease states.Key ConceptsFDCs trap antigens as immune complexes that consist of antigen in the presence of either specific antibodies or complement proteins, or both. FDCs trap immune complexes using CD32 and/or CD21.FDC‐trapped antigens or iccosomes are highly immunogenic and minute amounts (picogram) can induce significant quantities (microgram) of a specific antibody.FDC‐trapped antigens remain on the surface of FDCs and are not internalised. These antigens are not degraded but maintain their native configuration and immunoreactivity for many months.In addition to trapping conventional antigens, FDCs also trap HIV (and potentially other viruses) and maintain the infectious nature for many months. FDC‐trapped HIV can transmit infection to adjacent target cells (e.g. CD4+T lymphocytes).FDCs provide both antigen and other signals that are central to the induction and maintenance of specific antibody responses.FDCs can play roles in both health and disease (e.g. HIV/AIDS, prion diseases and follicular lymphomas).
Plant Storage Lipids
Authors: Murphy Denis J 
Published: February 2016

Abstract

Plant storage lipids, normally in the form of intracellular triacylglycerol‐rich droplets, are important sources of nutrition for people and livestock; besides, they supply a vast range of renewable industrial products from oleochemicals and bioplastics to paints and biofuels. Storage lipids are mainly found in plant propagules such as seeds and pollen grains, where they form an energy source for post‐germinative growth. The main commercial sources of plant storage lipids are oilseed crops such as soybean, rapeseed and maize or oil‐rich fruits such as olive or oil palm. Triacylglycerols also have several additional nonstorage functions in processes including host–pathogen interactions and abiotic stress responses. Improved knowledge of storage lipid metabolism is being used to create new oil crop varieties and to domesticate new species to supply the ever‐increasing demand for plant oils.

Key Concepts

How plants store energy reserves in the form of lipids.

What are the key storage lipids in plants.

How are plant storage lipids synthesised.

Where are store lipids made in plant cells.

What are the biotechnological uses of plant storage lipids.

How is storage lipid metabolism regulated and how can it be manipulated.
Species Richness: Small Scale
Authors: Brown Rebecca L , Reilly Lee Anne J , Peet Robert K 
Published: February 2016

Abstract

Species richness, defined as the number of species per unit area, is the simplest measure of biodiversity. Small‐scale species richness generally refers to species richness at the scale of a single community, habitat or microhabitat. Understanding the factors that affect and are affected by small‐scale species richness is fundamental to understanding how ecological communities are assembled and function and how biodiversity is maintained. Several factors affect small‐scale species richness, including geographic factors such as the regional species pool, dispersal distance and ease of dispersal, biological factors such as competition, facilitation, and predation as well as environmental factors such as resource availability, environmental heterogeneity and disturbance frequency and intensity. The importance of these factors varies with scale of observation. Further, small‐scale richness can impact aspects of ecosystem function including productivity, stability, and invasibility.

Key Concepts

Small‐scale species richness is the number of species per unit area at the scale of a single community, habitat or microhabitat.

Species richness is similar to alpha (α) diversity, or the number of species occurring at the local scale in a relatively homogeneous area.

Many factors affect small‐scale species richness, including geographic (e.g. species pool, dispersal), biotic (e.g. competition, predation, facilitation) and abiotic (e.g. resource availability, environmental heterogeneity, disturbance frequency and intensity).

The species pool is the set of species adapted to a site that are regionally available to colonise that site, and, in conjunction with dispersal processes, define the universe from which the ecological community is assembled.

Immigration is affected by the distance between suitable habitat sites and the ability of propagules to become established at the local site, and can significantly increase species richness.

Competition tends to decrease small‐scale richness, and its impact is shaped by resource availability, the specific resources being competed for and ecological disturbances that reduce competition.

Interactions among predators and prey, or pathogens and parasites and their hosts, can maintain or alter small‐scale diversity, the impact being largely dependent on the level of dominance of the species directly impacted.

While there is some evidence of a positive relationship between small‐scale richness and productivity, other factors such as the number and identity of functional groups may be the direct cause of the relationship.

Small‐scale richness has complex effects on the stability and invasibility of local sites.
Centrosome in Cell Division, Development and Disease
Authors: Buchwalter Rebecca A , Chen Jieyan V , Zheng Yiming , Megraw Timothy L 
Published: February 2016

Abstract

The centrosome is a non‐membrane‐bound organelle present in most animal cells and it functions as the major microtubule‐organising centre (MTOC). Recent findings have revealed the detailed molecular and structural features of the centrosome, and architectural and functional changes at the centrosome during the cell cycle. The centriole, the organisational heart of the centrosome, duplicates once each cell cycle and depends on a hierarchy of regulatory and assembly factors for its biogenesis. The centrosome plays important roles in dividing and nondividing cells. This importance is reflected in the appearance of several human developmental disorders when genes encoding centrosomal proteins are mutated. The centriole is essential for the formation of cilia, the cell's ‘antennae’ that receive and transmit signals and sensory inputs critical for animal development and physiology. Impairment of cilium structure or function leads to a spectrum of diseases called ciliopathies.

Key Concepts

The centrosome typically contains a centriole pair, the mother and its daughter, and the pericentriolar material (PCM).

Centrioles have a ninefold radial symmetry and are required for organising a functional centrosome.

The PCM is a large multi‐protein complex that regulates microtubule (MT) assembly at centrosomes in dividing and nondividing cells.

Centrioles duplicate only once each cell cycle, and the protein kinase PLK4 is a key early regulator of centriole duplication and biogenesis.

The cartwheel at the proximal end of the centriole is assembled early in centriole biogenesis, and its ninefold symmetry is determined by the intrinsic properties of the key structural protein Sas‐6.

The centrosome is involved in the asymmetric division of stem cells.

In nondividing cells, the basal body, a modified mother centriole, serves as a platform for organising the MT‐based axoneme, forming a primary or motile cilium.

Most vertebrate cells contain a primary cilium that is critical for signalling pathways including Hedgehog (Hh) signalling and left–right asymmetry designation during development.

Centrosomal and ciliary dysfunctions have been linked to two types of diseases: microcephaly/primordial dwarfisms, and ciliopathies, respectively.
Development of the Mammalian Gonad: Key Sex‐Determining Genes in Mice and Humans
Authors: Warr Nick , Greenfield Andy 
Published: February 2016

AbstractSex determination is the process by which an embryo commits to the male or female gonadal fate. Our understanding of mammalian sex determination is dominated by the consideration of data from humans and mouse models. Humans and mice share important elements of their reproductive biology, and therefore experimentation in the mouse offers the prospect of detailed mechanistic insights into typical and atypical human sexual development. Recent studies reveal a high degree of conservation in the roles played by sex‐determining genes in mice and humans, but also important differences. Key themes that have emerged from mouse genetics studies include the mutually antagonistic roles of testis‐ and ovary‐determining genes and the requirement to maintain these long after the primary sex‐determining event. The advent of technologies such as next‐generation sequencing and genome editing promises to shed more light on the causes of disorders of sex development in humans, as well as fundamental mechanisms in cell fate commitment in the mammalian gonad.Key ConceptsThe mammalian gonad (testis or ovary) develops from a bipotential primordium in which genes associated with later sexual differentiation are expressed.The testis‐ and ovary‐determining gene networks are mutually antagonistic during primary sex determination.The maintenance of cell identity in the differentiated adult gonad requires continued inhibition of opposing genetic pathways.Interpreting the nature of mutations associated with human genetic disease, including disorders of sex development (DSD), is aided by the generation and study of mouse models.
Evolutionary Ecology of Specialisation
Authors: Vamosi Jana C , Poisot Timothée 
Published: February 2016

Abstract

The processes that drive the evolution of specialisation are still poorly understood. While theory generally invokes the assumption that generalists bear costs compared to species that have a less intense exploitation of specific resources, the existence of these costs have not received strong empirical support. Recent studies have broadened the dialogue by examining specialisation from a macroevolutionary perspective. Are specialist lineages transitioning towards a broader niche under certain environmental conditions, or are they limited in their evolutionary potential and doomed to eventual extinction? The overall finding is that context dependency is key to driving rapid transitions in niche dimensions and composition. Answers to these questions are fascinating in terms of better understanding the natural world and also have the potential to improve prioritisation of future conservation efforts.

Key Concepts

Many ideas about the evolution of specialisation rely on the premise that ‘Jack of all trades is master of none’, that is, generalists are locally outperformed by specialists.

Genetic or physiological trade‐offs imply that populations experience reduced performance in one function when selection results in increased performance on another function (antagonistic pleiotropy).

The evolution of specialisation depends on how often alternate hosts or environments are encountered, which depends on abundance and range extent of a species and its neighbours.

Biogeography, functional trait distributions and range limits create ‘forbidden links’ by precluding pairs of species, or a species and a particular suite of environmental variables, from coexisting.

The idea of specialisation applies equally to a species biotic and abiotic niche, yet the expectations for how specialisation may evolve for each aspect of niche may differ.

Evolutionary transitions from specialisation to generalisation are common (and vice versa), yet specialists may experience greater extinction rates due to smaller geographical range.

The evolutionary ecology of specialisation is emerging as a key component in studies of host–pathogen evolution and conservation biology.
Comparison of the Utility and Validity of Three Scoring Tools to Measure Skin Involvement in Patients With Juvenile Dermatomyositis
Authors: Campanilho‐Marques Raquel , Almeida Beverley , Deakin Claire , Arnold Katie , Gallot Natacha , de Iorio Maria , Nistala Kiran , Pilkington Clarissa A. , Wedderburn Lucy R. ,   on behalf of the Juvenile Dermatomyositis Research Group
Published: February 2016

ObjectiveTo compare the abbreviated Cutaneous Assessment Tool (CAT), Disease Activity Score (DAS), and Myositis Intention to Treat Activity Index (MITAX) and correlate them with the physician's 10‐cm skin visual analog scale (VAS) in order to define which tool best assesses skin disease in patients with juvenile dermatomyositis.MethodsA total of 71 patients recruited to the UK Juvenile Dermatomyositis Cohort and Biomarker Study were included and assessed for skin disease using the CAT, DAS, MITAX, and skin VAS. The Childhood Myositis Assessment Scale (CMAS), manual muscle testing of 8 groups (MMT8), muscle enzymes, inflammatory markers, and physician's global VAS were recorded. Relationships were evaluated using Spearman's correlations and predictors with linear regression. Interrater reliability was assessed using intraclass correlation coefficients.ResultsAll 3 tools showed correlation with the physician's global VAS and skin VAS, with DAS skin showing the strongest correlation with skin VAS. DAS skin and CAT activity were inversely correlated with CMAS and MMT8, but these correlations were moderate. No correlations were found between the skin tools and inflammatory markers or muscle enzymes. DAS skin and CAT were the quickest to complete (mean ± SD 0.68 ± 0.1 minutes and 0.63 ± 0.1 minutes, respectively).ConclusionThe 3 skin tools were quick and easy to use. The DAS skin correlated best with the skin VAS. The addition of CAT in a bivariate model containing the physician's global VAS was a statistically significant estimator of skin VAS score. We propose that there is scope for a new skin tool to be devised and tested, which takes into account the strengths of the 3 existing tools.
Metastabiles Salpetersäuretrihydrat in Eiswolken
Authors: Weiss Fabian , Kubel Frank , Gálvez Óscar , Hoelzel Markus , Parker Stewart F. , Baloh Philipp , Iannarelli Riccardo , Rossi Michel J. , Grothe Hinrich 
Published: February 2016

AbstractDie Zusammensetzung von hochliegenden Eiswolken ist ein intensiv diskutierter Gegenstand der aktuellen Forschung. Die Bildungsmechanismen und die genaue Phasenzusammensetzung sind, nicht zuletzt aufgrund der schwierigen Zugänglichkeit, noch nicht endgültig aufgeklärt. Hier wird eine lange vermutete, aber strukturell unbekannte Phase vorgestellt. Diese Phase ist alpha‐Salpetersäuretrihydrat (alpha‐NAT), eine metastabile Phase von NAT. Mittels Röntgen‐ und Neutronendiffraktionsexperimenten wurde die Phase analysiert und daraus eine schlüssige Struktur abgeleitet. Schwingungsspektren wurden aufgenommen und mit theoretischen Berechnungen verglichen. Es konnte eine starke Interaktion zwischen Eis und alpha‐NAT beobachtet werden, was die experimentellen Spektren und die Kinetik beim Phasenübergang erklärt. Auf Grundlage der ermittelten Ergebnisse wird ein dreistufiger Prozess zur Bildung von NAT in stratosphärischen Wolken vorgeschlagen.
Mild Cobalt‐Catalyzed Negishi Cross‐Couplings of (Hetero)arylzinc Reagents with (Hetero)aryl Halides
Authors: Haas Diana , Hammann Jeffrey M. , Lutter Ferdinand H. , Knochel Paul 
Published: February 2016

AbstractA catalytic system consisting of CoCl2⋅2 LiCl (5 mol %) and HCO2Na (50 mol %) enables the cross‐coupling of various N‐heterocyclic chlorides and bromides as well as aromatic halogenated ketones with various electron‐rich and ‐poor arylzinc reagents. The reactions reached full conversion within a few hours at 25 °C.
Multifunctional Antioxidants: Regenerable Radical‐Trapping and Hydroperoxide‐Decomposing Ebselenols
Authors: Kumar Shailesh , Yan Jiajie , Poon Jia‐fei , Singh Vijay P. , Lu Xi , Karlsson Ott Marjam , Engman Lars , Kumar Sangit 
Published: February 2016

AbstractRegenerable, multifunctional ebselenol antioxidants were prepared that could quench peroxyl radicals more efficiently than α‐tocopherol. These compounds act as better mimics of the glutathione peroxidase enzymes than ebselen. Production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in human mononuclear cells was considerably decreased upon exposure to the organoselenium compounds. At a concentration of 25 μm, the ebselenol derivatives showed minimal toxicity in pre‐osteoblast MC3T3 cells.
The Effect of Hydrophile Topology in RAFT‐Mediated Polymerization‐Induced Self‐Assembly
Authors: Lesage de la Haye Jennifer , Zhang Xuewei , Chaduc Isabelle , Brunel Fabrice , Lansalot Muriel , D'Agosto Franck 
Published: February 2016

AbstractPolymerization‐induced self‐assembly (PISA) was employed to compare the self‐assembly of different amphiphilic block copolymers. They were obtained by emulsion polymerization of styrene in water using hydrophilic poly(N‐acryloylmorpholine) (PNAM)‐based macromolecular RAFT agents with different structures. An average of three poly (ethylene glycol acrylate) (PEGA) units were introduced either at the beginning, statistically, or at the end of a PNAM backbone, resulting in formation of nanometric vesicles and spheres from the two former macroRAFT architectures, and large vesicles from the latter. Compared to the spheres obtained with a pure PNAM macroRAFT agent, composite macroRAFT architectures promoted a dramatic morphological change. The change was induced by the presence of PEGA hydrophilic side‐chains close to the hydrophobic polystyrene segment.
TiO2 Nanotubes: Nitrogen‐Ion Implantation at Low Dose Provides Noble‐Metal‐Free Photocatalytic H2‐Evolution Activity
Authors: Zhou Xuemei , Häublein Volker , Liu Ning , Nguyen Nhat Truong , Zolnhofer Eva M. , Tsuchiya Hiroaki , Killian Manuela S. , Meyer Karsten , Frey Lothar , Schmuki Patrik 
Published: February 2016

AbstractLow‐dose nitrogen implantation induces an ion and damage profile in TiO2 nanotubes that leads to “co‐catalytic” activity for photocatalytic H2‐evolution (without the use of any noble metal). Ion implantation with adequate parameters creates this active zone limited to the top part of the tubes. The coupling of this top layer and the underlying non‐implanted part of the nanotubes additionally contributes to an efficient carrier separation and thus to a significantly enhanced H2 generation.