bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subglacial hydrology as a control on emergence,scale, and spacing of ice streams
Authors: Kyrke‐Smith T. M. , Katz R. F. , Fowler A. C. 
Published: July 2015

AbstractObservations have long associated ice streams with the presence of meltwater at the bed. More recently, theoretical models have been able to reproduce ice stream behavior as a consequence of the coupled dynamics of ice and subglacial meltwater. In this paper we analyze the properties of ice streams that form in a coupled model of ice flow and subglacial hydrology. We see that there is a natural length scale defining ice stream separation and width. This arises as a result of the balance between effective pressure gradients driving meltwater away from ice streams and the enhanced water production in the streams due to the fast ice flow. We further discuss how the model interacts with topography, and we show that small perturbations to a uniform bed have a strong effect on where ice streams emerge in the model. However, in many cases ice streams then evolve to be closer to the dimensions defined by the natural length scale of the unperturbed system. The nondimensional parameter that defines this length scale is therefore of fundamental importance in the model.
Simulating depth‐averaged, one‐dimensional turbidity current dynamics using natural topographies
Authors: Traer M. M. , Fildani A. , McHargue T. , Hilley G. E. 
Published: July 2015

AbstractThis study simulates turbidity currents through natural submarine topographies using a steady, one‐dimensional, depth‐averaged model to determine if modeled flows might traverse the length of channel forms observed at the seafloor or in shallow seismic data sets. To accomplish this, we calculated flow dynamics based on 50,000 sets of initial conditions drawn randomly between prescribed bounds and identified those conditions that allowed flows to traverse the naturally observed systems. We also used flow height and velocity to rule out initial conditions that produced flows that would be broadly accepted as unrealistic. We found that a small percentage (2.3–9.7%) of flows traversed the measured portion of these natural systems and maintained plausible peak depth‐averaged velocities when laboratory‐derived clear‐water entrainment rules were used. However, even these flows reached peak heights that were many times (10–200) greater than that of the channel bottom to levee crest relief. When clear‐water entrainment was removed from the model, a larger percentage of flows (34.5–41.6%) traversed the measured channel geometries, maintained lower ranges of flow height, and typically had higher flow velocities. Alternate entrainment relationships allowed flows to maintain realistic flow heights and velocities. We speculate that the unrealistic flows produced using clear‐water entrainment rules arise because flow loss through stripping and/or overbank collapse is neglected in this one‐dimensional model, or extrapolating laboratory‐measured clear‐water entrainment rules to the field is problematic.
Bacterial Capsules and Evasion of Immune Responses
Authors: Merino Susana , Tomás Juán M 
Published: July 2015

Abstract

The bacterial surface contains various structures that are capable of activating the host defences and consequently inducing host immune responses. Bacterial capsules are one of the most external structures on the bacterial surface, which may completely surround all the antigenic molecules or may be coexpressed with other bacterial antigens. They are involved in a wide range of biological processes, such as prevention of desiccation, adherence and resistance to nonspecific and specific host immunity.
Gram‐negative and Gram‐positive capsular polysaccharides contribute to the bacterial resistance of host immune responses by different mechanisms. Usually, capsular polysaccharides that mask the underlying cell surface structures activate weakly or not at all the immune system, whereas bacterial capsules coexpressed with other bacterial antigens activate the immune system but mask opsonines and prevent complement attack complex formation, as well as phagocytosis.

Key Concepts

Bacterial capsules completely surround bacterial cell and enhance the ability of bacteria to cause disease.

Polysaccharides are polymeric carbohydrate structures, formed of one or more sugar residues repeating units joined together by glycosidic bonds.

Antigenic variation modifies microorganism's surface structures and allows them to overcome the immune response.

Phagocytosis is the process by which certain cells called phagocytes engulf and digest a solid particle as bacteria.

The complement system is a part of the innate immune system and consists of a number of plasma small proteins which circulating as inactive precursors and after their activation cascade are able to serve as opsonins.
Graft Rejection: Immunological Suppression
Authors: Afzali Behdad , Lechler Robert , Lombardi Giovanna 
Published: July 2015

AbstractTransplantation of solid organs is the treatment of choice for most patients with end‐stage organ diseases. In the absence of pharmacological immunosuppression, recognition of foreign (allogeneic) histocompatibility proteins expressed on donor cells by the recipient's immune system results in rejection of the transplanted tissue(s). One‐year renal transplant survival is now routinely over 90% in most centres, largely the result of improvements in immunosuppressive drugs. In this article, we review commonly used immunosuppressive medications and discuss their pharmacological modes of action. Given that the long‐term graft outcomes remain poor, despite improvements in early transplant survival, we discuss, in addition, novel experimental strategies for the induction of tolerance to transplanted tissues that have translational relevance to human organ recipients.Key ConceptsThe major limitation of solid organ transplantation is long‐term immunosuppression, which either results in excessive mortality and morbidity or is insufficient to prevent chronic rejection of transplanted tissues.An understanding of transplant rejection and pharmacological targets of immunosuppression is a key to devising novel strategies of preventing rejection by inducing transplant tolerance.
Bone Homeostasis: Extracellular Calcium Levels and Their Control in Humans
Authors: McDonald Fraser 
Published: July 2015

AbstractCalcium (Ca2+) is an essential ion within the human body. It is extraordinary as an ion whose homeostasis is controlled and managed by many organs (bone, intestine, kidney, skin and thyroid). For a student, Ca2+is a clear example of the complexities of biological control, integrating many systems. The understanding of the basic principles of control of this ion is a very sound foundation for consideration of other biological control mechanisms. The ion is responsible for the correct coordination of many functions (including excitable (muscle and nerve) and nonexcitable (endocrine in particular but also cellular enzymatic functions) tissue) and constitutes a large part of the inorganic component of the skeleton in the form of hydroxyapatite crystals. Calcium levels are kept within a narrow and specific range (7.5–11.5 mg/dL−1in health; varying with age) and are regulated principally by three hormones – parathyroid hormone, calcitonin and cholecalciferol (vitamin D3). Other paracrine substances can also have a major effect. Excessive variations can lead to abnormalities of nerve function and porous bones (hypocalcaemia) or pathological calcification (hypercalcaemia).Key ConceptsCa2+is a unique ion maintaining both the independent functional capacity of the organism being part of the rigid endoskeleton and having unique microlevel qualities controlling, very precisely, cell function.Release and uptake of Ca2+from the skeleton is undertaken by osteoblasts (bone depositing cells), osteoclasts (bone dissolving cells) and may have some influence from osteocytes (osteoblasts when surrounded by bones) and bone lining cells (thin cells possibly controlling ion exchange with bone).Its characteristic role at cellular level can control ‘immediate’ cellular events such as exocytosis and contraction.It is responsible for intercellular adherence.It can influence chromosome functions.It is integral to activation of enzyme systems.As an ion whose serum levels are controlled closely, it demonstrates clearly basic principles of homeostasis that can serve as a foundation for understanding control of other ions/metabolites.The control of serum Ca2+demonstrates very clearly the interaction of several systems that are required to function correctly.Ca2+is a major coordinator of programmed cell death as well as a significant second messenger.
Cystinuria
Authors: Goldfarb David S 
Published: July 2015

Abstract

Cystinuria accounts for 1% of kidney stones in adults and up to 5–7% of stones in children. The two genes responsible for the disorder,
SLC3A1
and
SLC7A9
. The genes code, respectively, for proteins called rBAT and b
0,+
AT, both of which are necessary for the proximal tubule of the nephron to reabsorb cystine filtered by the glomerulus. The identification of
SLC3A1
made cystinuria the first disorder of amino acid transport with an identified gene. Most patients are affected by autosomal recessive inheritance, but a mutation in one allele of
SLC
7
A9
may sometimes be sufficient to form stones, constituting autosomal dominant inheritance with variable penetrance.
l
‐Cystine is poorly soluble and precipitates in the urinary tract to form stones which are often large and recurrent. Stone removal with urologic interventions such as ureteroscopy may be required. Prevention of stone recurrence is directed at increasing the solubility of cystine. New inhibitors of cystine crystal growth have been identified and may be effective
in vitro
and
in vivo
in a knock‐out mouse model.

Key Concepts

Cystinuria accounts for 1% of kidney stones in adults and up to 5–7% of stones in children.

The genes responsible for cystinuria,
SLC3A1
and
SLC7A9
, code, respectively, for proteins called rBAT and b
0,+
AT, both of which are necessary for the proximal tubule of the nephron to reabsorb cystine filtered by the glomerulus.

The amino acid
l
‐cystine is a homodimer of two molecules of the amino acid cysteine, linked by a disulfide bond.

Amino acids are present in the plasma, filtered by the glomerulus and reabsorbed by the proximal tubule. Normally, the amount of cystine in the urine is <1% of filtered cystine but in cystinuria, there may be more than 100% of filtered cystine.

Most patients are affected by autosomal recessive inheritance, but a mutation in one allele of
SLC
7
A9
may sometimes be sufficient to form stones, constituting autosomal dominant inheritance with variable penetrance.

The only clinical manifestation of cystinuria is kidney stones. Cystine is poorly soluble and precipitates in the urinary tract to form stones which are often large and recurrent.

Stone removal with urologic interventions such as ureteroscopy may be required.

Prevention of stone recurrence is directed at increasing the solubility of cystine. Increased fluid intake increases urine volume and dilutes cystine. Ingestion of alkali increases urine pH and increases cystine solubility. Restriction of dietary animal protein and salt will decrease the amount of cystine in the urine.

Two thiol drugs,
d
‐penicillamine and tiopronin, break the disulfide bridge of cystine and form drug–cysteine complexes which are soluble in the urine.

New potential drugs, identified by atomic force microscopy, have been identified as novel mimics of cystine that can inhibit cystine crystal growth. They appear effective
in vitro
and
in vivo
in a mouse model in which
Slc3a1
has been knocked out.
Mass Spectrometry: Analysis of Two‐Dimensional Protein Gels
Authors: Paradela Alberto 
Published: July 2015

AbstractIntroduced two decades ago, two‐dimensional gel electrophoresis (2‐DE) in combination with mass spectrometry has since been a powerful tool to analyse and to describe the enormous complexity hidden in the proteomes. Massively used by the academic community in the last two decades, it has lost its privileged status in favour of other high‐throughput approaches, such as liquid chromatography coupled to mass spectrometry (LC‐MS). Nevertheless, 2‐DE is still a useful tool to describe both in qualitative and quantitative terms the complexity of the proteome, offering some advantages over ‘peptide‐centric’ approaches such as LC‐MS and a more ‘realistic’ view of common post‐translational processes that modify both the structure and function of proteins, including alternative splicing processes and common post‐translational modifications such as phosphorylation and glycosylation. In addition, continuous improvements in gel imaging software have greatly improved the utility of 2‐DE for quantitative experiments.Key ConceptsAnalysis of complex proteomes demand the use of high‐resolution separation techniques.Immobilised pH gradients increase the resolution power of two‐dimensional gel electrophoresis (2‐DE) while reducing experimental variability.2‐DE gel‐based protein analysis has lost predominance in favour of peptide‐centric experimental approaches.2‐DE is a powerful experimental approach to compare complex proteomes quantitatively.2‐D DIGE significantly reduces artefactual gel‐to‐gel variability.Development of soft‐ionisation techniques made it possible to analyse peptides and proteins by means of mass spectrometry.MALDI TOF TOF mass spectrometers are best suited for the analysis of 2‐DE protein spots.High performance liquid chromatography can be directly coupled to ESI‐based mass spectrometers.
In VivoAnalysis of Membrane Fusion
Authors: Palfreyman Mark T , Jorgensen Erik M 
Published: July 2015

AbstractMembranes provide a barrier that allows chemical reactions to be isolated from the environment. The plasma membrane, for example, delineates self from nonself, and thus must have played an essential role in the evolution of life. Yet under numerous circumstances it is equally important that membranes be breached. Numerous forces oppose the spontaneous fusion of membranes; thus, specialised proteins have evolved to fuse membranes. The most well‐understood fusion proteins are the viral fusion proteins and the SNARE proteins used in the secretory pathway. Recent discoveries have added to the list of fusogens for which necessity and sufficiency have been demonstrated. The list now includes the fusion family proteins, used in cell–cell fusion, and the dynamin‐related proteins, used in organelle fusion. Despite, the diverse structures of fusion proteins, it is likely that they all function to drive membranes through a series of common lipid intermediates. In this article, we review the mechanisms of fusion for biological membranes, and highlight the similarities and differences in these processes.Key ConceptsFusion proteins can be divided into three major classes: the secretory pathway uses SNARE proteins, cell–cell fusion uses proteins related to viral fusogens and organellar fusion is driven by dynamin‐related GTPases.Fusion proteins are thought to lead membranes through the common set of lipid intermediates: lipid stalk, hemifusion diaphragm and pore formation.Fusion proteins, either SNAREs or viral proteins, play an active role in all steps of the fusion process.Multimerisation of fusogens improves efficiency and in many instances is a requirement for fusion.Diverse proteins act as the fusogens in cell–cell fusion; many remain undiscovered.
Terrorism
Authors: Weimann Gabriel 
Published: July 2015

Abstract
Modern terrorists became aware of the new opportunities for exerting mass psychological impact using the latest means of mass communication. Academic observers remarked increasingly on the theater‐like nature of terrorist operations. According to this notion, modern terrorism can be understood in terms of the production requirements of theatrical engagements. Several terrorist organizations realized the potential of media‐oriented terror, in terms of effectively reaching huge audiences. Postmodern terrorists are taking advantage of the fruits of globalization and modern technology—especially the most advanced communication technologies. The Internet and its numerous platforms are becoming more popular among terrorists: in addition to launching their own websites, terrorists harness the interactive capabilities of the Internet using chatrooms, instant messaging, blogs, video‐sharing websites, and postings on Facebook, MySpace, Twitter, and YouTube.
Communitarianism
Authors: van Leeuwen Bart 
Published: July 2015

AbstractCommunication generates and sustains community by expressing shared understandings. Communitarianism represents a school of political thought, developed in the 1980s, that argues for the moral and political relevance of such shared understandings and communal solidarity, thereby challenging the abstract and individualist tendencies of contemporary liberalism. Communitarianism argues that culture and shared values constitute the identity of individuals. Therefore it defends a politics of the common good. Communitarian politics has been argued for at different levels of society: the national, the local, and the intermediate subnational level. In the first case it overlaps with, or touches upon, nationalism and in the last case with a politics of difference or multiculturalism.
Online Elections
Authors: Gibson Rachel K. 
Published: July 2015

AbstractThe impact of the Internet on politics in general and within the electoral arena in particular has been the subject of increasing academic study and debate. In this entry we examine those debates at two levels. First, on the supply side we look at the effects of the new interactive Web technologies on campaigns and parties and particularly how they affect the centralized and professionalized model of operation that has dominated until now. Does the digital era challenge the power of elites and place more power in the hands of grassroots supporters? Second, we turn to changes at the mass level and outline the main argument that the arrival of the Internet has inspired among scholars of participation—namely whether use of the Web increases people's engagement with politics and their likelihood to turn out to vote. We conclude by locating online elections and the change associated with them in the wider context of digital politics.
Stereotype
Authors: Sibley Chris G. , Osborne Danny 
Published: July 2015

Abstract
Stereotypes are specialized schemas adapted for the social world that people use to understand and predict the behavior of others. These predictions often contain substantial inaccuracies and cause people to see what they expect to see. Stereotyping unfolds over a two‐stage sequential process. First, cues in the environment automatically activate stereotypes. Controlled processes may then inhibit the application of the activated stereotype, and this is more likely to occur if the person is not under excessive cognitive load. Stereotypes tend to be based on specific content relating to judgments of warmth and competence. These two social judgments reflect the perceived intention of others toward us (are they friend or foe?) and their capacity to act on their intentions. Groups seen as competing with the ingroup or the dominant reference group will tend to be stereotyped as colder and as having more negative intentions toward the ingroup. Groups seen as higher in status will tend to be stereotyped as higher in competence and more able to act on their intentions. The combination of warmth–competence stereotypes in turn elicits different forms of discriminatory behaviors directed toward the group.
Gender and Politics
Authors: Wahl‐Jorgensen Karin , Ye Weihua 
Published: July 2015

Abstract
The relationship between gender and politics has unfolded in the context of male domination. Questions of representation and its consequences for political gender equality have always been central to understanding this relationship, as women politicians have consistently been underrepresented and subjected to essentialist constructions of femininity. But a shift toward more complex representations is making gender less salient than before, as female politicians are entering legislatures around the world in larger numbers.
Political Communication Research in the Middle East
Authors: Leihs Nadia , Roeder‐Tzellos Maria 
Published: July 2015

Abstract
This entry identifies the typical characteristics of authoritarian media systems. The press and broadcasting institutions of the MENA region have long been the mouthpieces of the national ruling elites and restricted by different mechanisms of control like direct and indirect censorship. Due to the high interconnectedness of politics and journalism, Arab journalists have developed professional values different from those of their western colleagues. The advent of transnational media, namely Arab satellite news channels, not only impacted these role conceptions but also laid the foundations for an evolving transnational public sphere. The space for political communication was further enhanced by the introduction of social network sites (SNSs) which provided for the articulation of dissident views and political mobilization.
Citizenship
Authors: Pasquino Gianfranco 
Published: July 2015

Abstract
The concept of citizenship and its practical implementation have a long and rich history. Both are tied at the same time with a political community and with a battery of rights to be enjoyed and duties to be performed. Citizenship is made of objective and subjective components: belonging and identity. The granting and the conquest of civil, political, and social rights have significantly contributed to the contemporary definition of citizenship. A cosmopolitan view of rights has made its recent appearance and has been translated into the concept of universal human rights. Almost at the same time, multiculturalism has challenged a central tenet of citizenship, that is, the equality each and all citizens before the law. The idea of group rights has been used to justify exceptions and practices that the liberal‐democratic theory and experience would consider highly objectionable. Transnational migrations, globalization, and the process of political unification of Europe suggest the need to (re)think in terms of supranational citizenship, its implication, its problems.