Multicarrier systems, such as car batteries and semiconductors, have surprisingly complex transport properties. Even for steady-state transport, one can find counterexamples to standard assumptions about local electroneutrality, constancy in space of the electric field, linearity in space of the voltage, and the relationship between dissipation, voltage, and current. Moreover, unless recombination processes occur, boundaries impose conditions that can disturb the response far into the bulk to remove memory of the boundaries. Because the demands of the chemical reactions (...) at the electrodes cannot be satisfied by diffusion alone, car batteries are electrically active even when they are neither charging nor discharging. We offer practical advice on battery care for bike-riders, say, who only occasionally use their cars. For semiconductors, recombination does occur, which in transport enables partial currents to adjust from their surface to their bulk values. For mixed ionic electronic conductors, bulk recombination may be essential to an understanding of “blocking electrodes.” The voltage associated with both current-producing and non-current-producing surface reactions provides a natural explanation for the bioelectric fields observed during root and other growth processes. (shrink)

Actors, undercover investigators, and readers of fiction sometimes report “losing themselves” in the characters they imitate or read about. They speak of “taking on” or “assuming” the beliefs, thoughts, and feelings of someone else. I offer an account of this strange but familiar phenomenon—what I call imaginative transportation.

Citrate, an organic trivalent anion, is a major substrate for generation of energy in most cells. It is produced in mitochondria and used either in the Krebs' cycle or released into cytoplasm through a specific mitochondrial carriers. Citrate can also be taken up from blood through different plasma membrane transporters. In the cytoplasm, citrate can be used ultimately for fatty acid synthesis, which is increased in cancer cells. Here, we review the ways in which citrate can be transported and discuss (...) the changes in transport and metabolism that occur in cancer cells. The primary focus is on the prostate gland, which is known to produce and release large amounts of citrate during its normal secretory function. The significant changes that occur in citrate‐related metabolism and transport in prostate cancer are the second focus. This review strives to relate these mechanisms to molecular biology on the one hand and to clinical applications on the other. (shrink)

The transport of molecules across the nuclear envelope plays a central role in the metabolism of the cell. Significant advances hi three major areas highlight the limits of our current knowledge and point to the prospect of exciting future developments. Firstly, findings that ions and small proteins do not diffuse freely into the nucleus call into question the current views of nuclear envelope permeability. Secondly, indications that nuclear protein import can be regulated in conjunction with the cell cycle and (...) development have been confirmed by the clear demonstration of regulated nuclear entry of specific transcription factors and morphogens. Thirdly, identification and characterisation of candidate receptor proteins indicates that the recognition of the nuclear targeting sequence occurs in the cytoplasm, suggesting that a different recognition event occurs at the nuclear pore. (shrink)

This chapter contains sections titled: The Transportation System Transportation System Benefits, Harms and Hazards Conclusions and Further Questions References and Further Reading.

We all know that problems of transportation and allocation appear frequently in practical life. We need to transfer materials from production centers to consumption centers to secure the areas’ need for the transported material or allocate machines or people to do a specific job at the lowest cost, or in the shortest time. We know that the cost factors Time is one of the most important factors that decision-makers care about because it plays an “important” role in many of the (...) practical and scientific issues that we face in our daily lives, and we need careful study to enable us to avoid losses. For this, the linear programming method was used, which is one of the research methods. Processes, where the problem data is converted into a linear mathematical model for which the optimal solution achieves the desired goal. Since these models are linear models, we can solve them using the direct simplex method and its modifications, but the specificity that these models enjoy has enabled scholars and researchers to find special methods that help us in obtaining the optimal solution. Whatever the method used, the goal is to determine the number of units transferred from any material from production centers to consumption centers, or to allocate a machine or person to do a job so that the cost or time is as short as possible. These issues were addressed according to classical logic, but the ideal solution was a specific value appropriate to the conditions in which the data was collected and does not take into account the changes that may occur in the work environment. In order to obtain results that are more accurate and enjoy a margin of freedom, we present in this book a study of transport issues and neutrosophic allocation issues and some methods for solving them. By neutrosophic issues we mean These are the problems in which the data are neutrosophic values, i.e. the required quantities and the available quantities. (shrink)

Adenosine transport in cultured human umbilical vein endothelial cells (HUVEC) was characterized and shown to be mediated by a single facilitated diffusion mechanism. Initial rates of adenosine influx at 22 degrees C were saturable [apparent Michaelis constant, 69 +/- 10 mu M; maximum velocity (V-max), 600 +/- 70 pmol.10(6) cells(-1).s(-1)] and inhibited by nitrobenzylthioinosine (NBMPR). Formycin B had an unusually high affinity [inhibitory constant K-i), 18 +/- 4.3 mu M], whereas inosine had a low affinity (K-i, 440 +/- 68 (...) mu M) and nucleobases were without effect on adenosine influx. The number of transporters (1.2 x 10(6) sites/cell) was estimated by NBMPR equilibrium binding (apparent dissociation constant, 0.11 +/- 0.01 nM; maximum binding, 2.0 +/- 0.15 pmol/10(6) cells). In addition, we compared these endothelial cells with those obtained from cords from pregnancies complicated by diabetes (HUVEC-D), since embriopathy may occur in these conditions. HUVEC-D exhibited a 2.3-fold reduction in both the V-max for adenosine influx and the maximum number of NBMPR binding sites (260 +/- 40 pmol.10(6) cells(-1).s(-1) and 0.86 +/- 0.08 pmol/10(6) cells, respectively). However, the turnover number for each nucleoside transporter in normal and diabetic HUVEC was similar (approximate to 300 adenosine molecules/s). Adenosine metabolism at 10 mu M in HUVEC-D was modified compared with normal cells. Intracellular phosphorylation (> 90%) was the predominant pathway in normal HUVEC, whereas in HUVEC-D, substantial levels of adenine and adenosine were detected. The present results demonstrate therefore the downregulation of the NBMPR-sensitive nucleoside transporter and changes in adenosine metabolism in HUVEC from diabetic pregnancies. (shrink)

The energy transport in one-dimensional nonlinear systems is discussed. By numerically studying a model system, we verify the Fourier heat law on purely dynamical grounds and we compute the coefficient of thermal conductivity K. The same value ofK is independently obtained by use of the Green-Kubo formalism.

When cells are starved of their substrate, many nutrient transporters are induced. These undergo rapid endocytosis and redirection of their intracellular trafficking when their substrate becomes available again. The discovery that some of these transporters also act as receptors, or transceptors, suggests that at least part of the sophisticated controls governing the trafficking of these proteins has to do with their signaling function rather than with control of transport. In yeast, the general amino acid permease Gap1 mediates signaling to (...) the protein kinase A pathway. Its endocytic internalization and intracellular trafficking are subject to amino acid control. Other nutrient transceptors controlling this signal transduction pathway appear to be subject to similar trafficking regulation. Transporters with complex regulatory control have also been suggested to function as transceptors in other organisms. Hence, precise regulation of intracellular trafficking in nutrient transporters may be related to the need for tight control of nutrient‐induced signaling. (shrink)

We question Baumard's underlying assumption that humans have a propensity to innovate. Affordable transportation and energy underpinned the Industrial Revolution, making mass production/consumption possible. Although we cannot accept Baumard's thesis on the Industrial Revolution, it may help explain why complexity and innovation increase rapidly in the context of abundant energy.

A recently developed formalism which gives a unified picture of the linear transport of moving frames is extended to include a particular type of transport under the 10-parameter Poincaré group. The frame coordinates are expressed in a 5 × 5 matrix representation which includes the position four-vector plus orthonormal tetrads for the internal coordinates. This provides a general description of the kinematics of physical systems which can be represented by moving frames. Several examples are given, including systems moving (...) with spin and Zitterbewegung along both timelike and null paths. The concept of boost or Poincaré momentum is related to system kinematics. Lagrangians of these systems are also discussed. (shrink)

Physiological studies show that the driving force for long distance transport and the control of nutrient movement in plants resides largely in the regulated, membrane transport of a few carbohydrates, principally sucrose. The evidence is reviewed here and biochemical studies on sucrose carrier proteins are discussed.

A major problem in the treatment of cancer is the specific targeting of anti‐tumor drugs to these abnormal cells. Ideally, such a drug should act over short distances to minimize damage to healthy cells, and target subcellular compartments that have the highest sensitivity to the drug. Photosensitizers, alpha‐emitting radionuclides and many other medicines could be considered as such drugs if they possessed cellular and subcellular specificity. The author describes a novel approach of using modular recombinant transporters to target photosensitizers and (...) alpha‐emitting radionuclides to the nucleus, where their action is most pronounced, of cancer cells. Photosensitizer‐transporter conjugates have up to 3000 times greater efficacy than free photosensitizers and display cell specificity in contrast to free photosensitizers. Alpha‐emitting radionuclides, conjugated with the modular transporters, acquired similar properties. The different modules of the transporters are interchangeable, meaning that they can be tailored for particular applications. BioEssays 30:278–287, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

In Southeast Asian countries (SEA), road transport accounts for the main energy consumption and CO2 emission. Air pollution is a major concern in densely populated cities such as Bangkok, Manila, and Kuala Lumpur. The main objective of this paper is to give insights on trends of transport development, car ownership, and CO2 emissions in Southeast Asia. This study also attempts to review the successful transportation policies around the globe and to introduce the possible instruments that can help reduce (...) air pollution in Southeast Asian countries. Economic instruments to estimate the benefits of a cleaner environment due to new policies are introduced as well. The results of this research could help policy makers consider approaches that could internalize external costs of transportation and maximize the societal welfare. (shrink)

Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and rapidly transported into the organelle by a complex machinery. The data gathered in recent years suggest that this machinery operates through a syringe-like mechanism, in which the shuttling receptor PEX5 − the “plunger” − pushes a newly synthesized protein all the way through a peroxisomal transmembrane protein complex − the “barrel” − into the matrix of the organelle. Notably, insertion of cargo-loaded receptor into the “barrel” is an ATP-independent process, whereas extraction (...) of the receptor back into the cytosol requires its monoubiquitination and the action of ATP-dependent mechanoenzymes. Here, we review the main data behind this model. The peroxin PEX5 is the peroxisomal matrix protein receptor. It shuttles between the cytosol and the organelle membrane, where it gets inserted into the docking/translocation module, thus pushing the cargo-protein into the peroxisome lumen. Resetting the system involves PEX5 monoubiquitination and its extraction from the membrane by the AAA-ATPases, PEX1/PEX6. (shrink)

The Gram-negative outer membrane is a potent permeability barrier against antibiotics, limiting clinical options amid mounting rates of resistance. The Lol transport pathway delivers lipoproteins to the OM. All the OM assembly machines require one or more OM lipoprotein to function, making the Lol pathway central for all aspects of OM biogenesis. The Lol pathways of many medically important species clearly deviate from the Escherichia coli paradigm, perhaps with implications for efforts to develop novel antibiotics. Moreover, recent work reveals (...) the existence of an undiscovered alternate route for bringing lipoproteins to the OM. Here, lipoprotein transport mechanisms, and the quality control systems that underpin them, is re-examined in context of their diversity. All essential outer membrane assembly machines require lipoproteins to function. Hence, the transport mechanisms supplying these lipoproteins are critical for maintaining the integrity of the outer membrane barrier against antibiotics. Lipoprotein transport strategies of diverse Gram-negative bacteria will be reviewed in the context of recent discoveries. (shrink)

La métaphore est un instrument indispensable pour les analyses scientifiques. Mais elle nécessite un usage réflexif qui en précise le statut car celui-ci peut être divers et n’est pas sans effet sur la théorie comme sur diverses pratiques. Ainsi, les analystes et acteurs des transports ont usé – et probablement abusé – du recours à la physique des fluides pour leurs métaphores. Aujourd’hui, les développements de la physique, par exemple dans les domaines des fractales ou de la percolation, ouvrent des (...) perspectives nouvelles et prometteuses. Cette évolution montre aussi que les chercheurs en sciences sociales auraient intérêt à renouveler les métaphores qu’ils emploient et qui sont souvent assez archaïques. Ainsi, la référence à des espaces à n dimensions et à l’hypertexte permet de faire rebondir les analyses de Georg Simmel, bridées par le recours à une géométrie plane trop sommaire.Metaphors are indispensable tools for scientific investigation. They should be used in such a way that their status as metaphor is clear, however, for their various uses are not without consequence for theory and practice. In the area of transportation, analysts and practitioners have drawn metaphors from the physics of fluids, but recent developments in the theories of fractals and percolation offer promising perspectives. Generally speaking, as these developments suggest, social scientists stand to benefit from renewing their current metaphors, which are often quite archaic. Thus, Georg Simmel’s analyses – which are constrained by the reference to plan – stand to be revitalized by a reference to N-dimensional spaces and to hypertext. (shrink)

The essential biological processes that sustain life are catalyzed by protein nano-engines, which maintain living systems in far-from-equilibrium ordered states. To investigate energetic processes in proteins, we have analyzed the system of generalized Davydov equations that govern the quantum dynamics of multiple amide I exciton quanta propagating along the hydrogen-bonded peptide groups in α-helices. Computational simulations have confirmed the generation of moving Davydov solitons by applied pulses of amide I energy for protein α-helices of varying length. The stability and mobility (...) of these solitons depended on the uniformity of dipole-dipole coupling between amide I oscillators, and the isotropy of the exciton-phonon interaction. Davydov solitons were also able to quantum tunnel through massive barriers, or to quantum interfere at collision sites. The results presented here support a nontrivial role of quantum effects in biological systems that lies beyond the mechanistic support of covalent bonds as binding agents of macromolecular structures. Quantum tunneling and interference of Davydov solitons provide catalytically active macromolecular protein complexes with a physical mechanism allowing highly efficient transport, delivery, and utilization of free energy, besides the evolutionary mandate of biological order that supports the existence of such genuine quantum phenomena, and may indeed demarcate the quantum boundaries of life. (shrink)

In all domains of life, transmembrane proteins from the ATP‐binding cassette (ABC) transporter family drive the translocation of diverse substances across lipid bilayers. In pathogenic fungi, the ABC transporters of the pleiotropic drug resistance (PDR) subfamily confer antibiotic resistance and so are of interest as therapeutic targets. They also drive the quest for understanding how ABC transporters can generally accommodate such a wide range of substrates. The Pdr5 transporter from baker's yeast is representative of the PDR group and, ever since (...) its discovery more than 30 years ago, has been the subject of extensive functional analyses. A new perspective of these studies has been recently provided in the framework of the first electron cryo‐microscopy structures of Pdr5, as well as emergent applications of machine learning in the field. Taken together, the old and the new developments have been used to propose a mechanism for the transport process in PDR proteins. This mechanism involves a “flippase” step that moves the substrates from one leaflet of the bilayer to the other, as a central element of cellular efflux. (shrink)

The EU has launched targets for energy efficiency and the reduction in pollutant emissions in the transport sector. It establishes a framework to foster the promotion and development of a market for clean vehicles. In 2011 the EU passed a “Roadmap to a single European transport area—Towards a competitive and resource efficient transport system”. This roadmap includes 40 concrete initiatives for the next decade to build a competitive transport system that will increase mobility, remove major barriers (...) in key areas and fuel growth and employment. The objectives concern well-functioning passenger and freight links that are vital for European undertakings and citizens. At the same time, the proposals will dramatically reduce Europe’s dependence on imported oil. All in all the EU transport policies aim at fostering clean, safe and efficient travel throughout Europe, which requires innovations in many areas—like safe electric cars—and needs to engage not just the users but the entire transport industry facing drastic structural changes. (shrink)

As it is essential to explore the influence of social communications on transportation routes in tourism, this article aims to examine the impacts of social communications on transportation routes in the field of tourism and to further explore the relationship between tourism destinations and their psychological perceptions. In terms of links between different tourism destinations in space and time dimensions, our empirical analysis draws the following conclusions: the behavior of tourist flow is a mediating variable on the links between tourist (...) psychological perceptions and tour routes; three modes of point-line interaction are presented in the space and time of tourism destinations; and the scenic city’s location, name, and features are important to tourists’ psychological perceptions. (shrink)

Organelles transported along microtubules are normally moved to precise locations within cells. For example, synaptic vesiceles are transported to the neruronal synapse, the Golgi apparatus is generally found in a perinuclear location, and the membranes of the endoplasmic reticulum are actively extended to the cell periphery. The correct positioning of these organelles depends on microtubules and microtubule motors. Melanophores provide an extreme example of organized organelle transport. These cells are specialized to transport pigment granules, which are coordinately moved (...) towards or away from the cell center, and result in the cell appearing alternately light or dark. Melanophores have proved to be an ideal system for studying the mechanisms by which the cell controls the direction of its organelle transport. Pigment granule dispersion (the movement away from the cell center) requires protein phosphorylation, while pigment aggregation (the movement towards the cell center) requires protein dephosphorylation. The target of this phosphorylation and dephosphorylation event is a protein that interacts with the microtubule motor protein, kinesin. Thus, the direction of organelle transport along microtubules may be regulated by controlling the activity of a microtubule motor. (shrink)

The demonstration that slow transport of clocks can be used to define simultaneity in inertial frames of reference leads to the question of whether clock transport can similarly be used in noninertial frames. It is shown that there are certain types of reference frames in which the clock-transport method cannot be used in a self-consistent manner. It is also shown that there are other types of noninertial frames in which the clock-transport method will succeed. The discussion (...) includes noninertial frames in flat space-time as well as the case of curved space-times. (shrink)

The complex spectral representation of the Liouville operator introduced by Prigogine and others is applied to moderately dense gases interacting through hard-core potentials in arbitrary d-dimensional spaces. Kinetic equations near equilibrium are constructed in each subspace as introduced in the spectral decomposition for collective, renormalized reduced distribution functions. Our renormalization is a nonequilibrium effect, as the renormalization effect disappears at equilibrium. It is remarkable that our renormalized functions strictly obey well-defined Markovian kinetic equations for all d, even though the ordinary (...) distribution functions obey nonMarkovian equations with memory effects. One can now define transport coefficients associated to the collective modes for all dimensional systems including d = 2. Our formulation hence provides a microscopic meaning of the macroscopic transport theory. Moreover, this gives an answer to the long-standing question whether or not transport equations exist in two-dimensional systems. The non-Markovian effects for the ordinary distribution function, such as the long-time tails for arbitrary n-mode coupling, are estimated by superposition of the Markovian evolutions of the dressed distribution functions. (shrink)

The American Journal of Bioethics, Volume 12, Issue 7, Page 19-21, July 2012.

Recent programs aimed at the independent living of persons with disabilities, allow them to be costumers of sectors in which they have never had full access in the past. The Lisbon Treaty has distinctly recognized the existence of a community tourist area within the primary law, and CRPD has defined the principles of accessibility and accessible tourism as tools for the inclusion. In addition, tourism and transportation stakeholders must guarantee non-discriminatory services; they must approach persons with disabilities as every other (...) customer, by taking in consideration their needs and rights, especially when it comes to their accessibility, assistance, and information. Companies of transportation must cooperate with DPOs in order to define disability-related training procedures. (shrink)

In recent years, philosophical examinations of automated vehicles have progressed far beyond initial concerns over the ethical decisions that pertain to programming in the event of a crash. In turn, this paper moves in that direction, focusing on the motivations behind efforts to implement driverless vehicles into urban settings. The author argues that the many perceived benefits of these technologies yield a received view of automated vehicles. This position holds that driverless vehicles can solve most if not all urban mobility (...) issues. However, the problem with such an outlook is that it lends itself to transportation planning for automated vehicles, rather than using them as part of planning efforts that could serve urban mobility. Due to this condition, present efforts aimed at improving transportation systems should resist dogmatic thinking. Instead, they should focus on goals that keep topics such a human flourishing, sustainability, and transportation justice firmly in view. (shrink)

Most metazoan organisms have evolved a mildly acidified and calcium diminished sorting hub in the early secretory pathway commonly referred to as the Endoplasmic Reticulum‐Golgi intermediate compartment (ERGIC). These membranous vesicular‐tubular clusters are found tightly juxtaposed to ER subdomains that are competent for the production of COPII‐coated transport carriers. In contrast to many unicellular systems, metazoan COPII carriers largely transit just a few hundred nanometers to the ERGIC, prior to COPI‐dependent transport on to the cis‐Golgi. The mechanisms underlying (...) formation and maintenance of ERGIC membranes are poorly defined. However, recent evidence suggests an important role for Trk‐fused gene (TFG) in regulating the integrity of the ER/ERGIC interface. Moreover, in the absence of cytoskeletal elements to scaffold tracks on which COPII carriers might move, TFG appears to promote anterograde cargo transport by locally tethering COPII carriers adjacent to ERGIC membranes. This action, regulated in part by the intrinsically disordered domain of TFG, provides sufficient time for COPII coat disassembly prior to heterotypic membrane fusion and cargo delivery to the ERGIC. -/- . (shrink)

Defined as the ability to understand and share others' feelings and suffering, empathy seems to come naturally to mind when we consider Simone Weil's life and works. If this concept doesn't explicitly appear in her writings, "pity", "sympathy" and "compassion" are pervasive: the purpose of this paper is to demonstrate how these notions converge on the contemporary understanding of "empathy". Since the turn of the century, this concept has known such a development that it has become difficult to clearly identify (...) its object, and to appreciate its ethical value. To study Simone Weil's works from the angle of empathy offers both a new approach of the concept, and a very relevant point of view to put in light the great continuity between all the fields of the philosopher's thought. Our main hypothesis is that the weilian theory of empathy is based on the idea of "transposition", a process that allows someone to transport himself into another person, and from the natural to the supernatural dimension. It is in this last dimension that Simone Weil can found intersubjectivity, and solve the ethical problem of empathy: the right distance between the Self and the Other. (shrink)

Atomic-scale computer simulation has been used to study the thermally activated atomic transport of self-interstitial atoms in the form of planar clusters in pure Cu and f -Fe. There is strong evidence that such clusters are commonly formed in metals during irradiation with high-energy particles and play an important role in accumulation and spatial distribution of surviving defects. An extensive study of the mobility of SIA clusters containing two to 331 interstitials has been carried out using the molecular dynamics (...) simulation technique for the temperature range from 180 to 1200 K. The results obtained show that clusters larger than three to four SIAs are one-dimensionally mobile in both Cu and Fe. Large clusters of more than 100 SIAs in Cu and 300 SIAs in Fe have significantly reduced mobility. The problem of describing one-dimensional motion in three-dimensional space is discussed. An attempt is made to describe the mobility of SIA clusters within the approximation of 1D diffusion. For clusters in both metals the effective migration energy of 1D diffusion as estimated via the jump frequency of the cluster centre of mass is found to be independent of the number of SIAs in the clusters, although the cluster jump frequency decreases with increasing cluster size. Mechanisms of 1D mobility of interstitial clusters are discussed. (shrink)

The realization of dwindling fossil fuel supplies and their adverse environmental impacts has accelerated research and development activities in the domain of renewable energy sources and technologies. Global energy demand is expected to rise during the next few decades, and the majority of today's energy is based on fossil fuels. Alternative energy sources and technologies can play a vital role in lowering or eliminating our reliance on fossil fuels. However, such a transition will require a large investment and will not (...) be reversible. The benefits of hydrogen and other liquid fuels as transportation fuels are not marginal, but the real urgency in greenhouse gas reductions and fossil fuel replacement should not be translated into an energy infrastructure based on unsustainable sources in the long run. It is wise to examine each option thoroughly and objectively now and discard those with little potential so our focus and effort may be placed elsewhere. (shrink)