Theory and Observation of Displacement Phenomena in Coadsorbed Films

Displacement refers to a surprising phenomenon observed in a number of adsorption systems. At low temperatures, some relatively inert gases, such as krypton (Kr) or methane ( CH4), are found to displace molecules from preadsorbed monolayer films of a more condensable species, such as carbon tetrachloride ( CCl4), from a graphite substrate. We present a simple thermodynamic model to explain displacement and make a prediction applicable to both first-order and continuous displacement processes. We also present measurements on CH4/CCl4 and Kr/CCl4 coadsorbed films from 77–112 K that verify our prediction and yield the CCl4 film spreading pressure

Coadsorption phase diagram for Kr/CCl4 on graphite

We present the results of an extensive calorimetric study of krypton coadsorbed on graphite precoated with a saturated monolayer of carbon tetrachloride. Combining the heat capacity data with film equation of state measurements from a previous study [W. J. Weber and D. L. Goodstein, Phys. Rev. Lett. 83, 3888 (1999)] permits construction of the Kr/CCl4 coadsorption phase diagram between 77 and 130 K. Kr succeeds in displacing the CCl4 from the surface, by a continuous process which results, at lower temperatures, in a film indistinguishable from that of pure Kr adsorbed on graphite. At higher temperatures, a new first-order phase transition, unique to the coadsorption system, is observed and likely indicates a transition to a mixed Kr/CCl4 film. Finally, measurements at higher Kr coverages reveal evidence for a high temperature extension of the reentrant layering phenomena previously observed for Kr on graphite

Mammalian cells in culture actively export specific microRNAs

The discovery of microRNAs (miRNAs) as a new class of regulators of gene expression has triggered an explosion of research, but has left many unanswered questions about how this regulation works and how it is integrated with other regulatory mechanisms. A number of miRNAs have been found to be present in blood plasma and other body fluids of humans and mice in surprisingly high concentrations. This observation was unexpected in two respects: first, the fact that these molecules are present at all outside the cell at significant concentrations; and second, that these molecules appear to be stable outside of the cell. In light of this it has been suggested that the biological function of miRNAs may also extend outside of the cell and mediate cell-cell communication^[1-5]^. Such a system would be expected to export specific miRNAs from cells in response to specific biological stimuli. We report here that after serum deprivation several human cell lines tested do export a spectrum of miRNAs into the culture medium. The export response is substantial and prompt. The exported miRNAs are found both within and outside of microvesicles and exosomes. We have identified some candidate protein components of this system outside the cell, and found one exported protein that plays a role in protecting miRNA from degradation. Our results point to a hitherto unrecognized and uncharacterized miRNA trafficking system in mammalian cells that may involve cell-cell communication

Review of Remote Beyond Compare: Letters of don Diego de Vargas to His Family from New Spain and New Mexico, 1675-1706

Spain was but a stepmother to me, for she banished me to seek my fortune in strange lands (130-31). Thus Diego de Vargas, a member of the untitled nobility, explained why he had set out for the Indies at age twenty-eight, leaving his wife and four children behind in Madrid. Thirty-two years later when Vargas died while on campaign against Apaches in New Mexico, he had not made his fortune nor returned to Madrid as planned. He had won fame, however, in New Mexico and New Spain. For his intrepid leadership of the reconquest of New Mexico following the stunning Pueblo Revolt of 1680, Vargas won the title of Marques de la Nava de Barcinas and a place in the history of a land that he described as at the ends of the earth and remote beyond compare (168)

Book Review: The Coronado Expedition from the Distance of 460 Years

The remarkable descriptions of places and people produced by Francisco Vázquez de Coronado\u27s expedition constitute the verbal baseline for measuring historical change in southwestern America. Those descriptions are most useful, however, when linked to modern locations. Many of the writers in this essential volume have set themselves to that task

Evidence that demands a verdict?

Source—Meaning—Receptor (SMR) theories of translation, such as dynamic equivalence and meaning-based theories, shifted focus from the equivalence of FORM to the equivalence of MEANING. SMR theories were a significant advance and have been the basis for many modern English translations. However, SMR theories were formulated when the dominant theory of communication was the code model. Consequently they presumed that meaning was determined almost entirely by a text (utterance) itself. This theory is now rejected in favor of theories that understand interpretation as the inferential product of the interaction of the text with (mind-mediated) context. These newer theories shift the focus from meaning, largely a semantic notion, to the pragmatic/rhetorical dimensions of the text. It is thus natural to wonder if there is evidence that a SMR approach to translation leads to pragmatic/rhetorical oversights that have negative effects on translations. Here I will propose some candidates, drawing them from various modern English translations

Collateral damage and what the future might hold. The need to balance prudent antibiotic utilization and stewardship with effective patient management

Increased severity of illness among hospitalised patients and an ageing population have led to an increased incidence of hospital acquired infections and represent a significant challenge to the clinician in terms of managing infections. The collateral damage which can occur with antibiotic therapy is also an important consideration when initiating empirical antibiotic therapy, particularly in patients who are seriously ill or immunocom-promised. Collateral damage is the term used to describe the adverse ecological effects of antibiotic therapy, such as the selection of drug-resistant organisms, and the adverse events associated with antibiotic therapy such as Clostridium difficile disease. Antibiotic use and ineffective infection control have been implicated in the development and spread of resistant Gram-positive and Gram-negative bacterial pathogens which are associated with increased mortality and morbidity, prolonged hospitalisation and increased costs. Carbapenem consumption and mechanical ventilation have been linked to colonisation or infection with problematic organisms including methicillin-resistant Staphylococcus oureus, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, while cephalosporin use has been associated with evolution of infections due to vancomycin-resistant enterococci (VRE) and Gram-negative bacilli producing extended-spectrum β-lactamases (ESBL), and to colonisation or superinfection with Clostridium difficile. The safety profile of antibiotics must also be taken into consideration when selecting therapy, and single broad-spectrum agents may provide excellent coverage with a low risk of adverse events. The use of single agents may be associated with lower costs, improved ease of administration and fewer drug-drug interactions. However, in an environment of increasing resistance, initial aggressive therapy may be required to avoid excessive mortality and morbidity. Ideally antibiotic therapy should be directed by culture and knowledge of local susceptibility patterns. Before culture results are available therapy may need to be initiated empirically to cover the likely pathogens. In neutropenic patients with fever the current guidelines recommend the use of empirical therapy at the onset of fever for all patients. Where no aetiology is identified, antibiotic therapy should continue for at least 2 weeks while aggressive attempts are made to define the source of fever. When the aetiology of infection has been identified, therapy should be adjusted to provide optimal treatment with the best safety profile and lowest cost. The principal of avoiding collateral damage provides a useful framework for selecting antibiotics for empirical therapy in today's changing environment

Book Review: The Coronado Expedition from the Distance of 460 Years

The remarkable descriptions of places and people produced by Francisco Vázquez de Coronado\u27s expedition constitute the verbal baseline for measuring historical change in southwestern America. Those descriptions are most useful, however, when linked to modern locations. Many of the writers in this essential volume have set themselves to that task

The structural status of Bora classifiers

I claim that Bora classifiers have the structural status of (bound) nouns, based on facts like the following: Some classifiers also occur as independent nouns (possibly with minor phonological differences). Classifiers have the referential properties typical of nouns. Like typical nominals, they denote classes of objects and may refer to a member of the class they denote. They are never used to attribute properties to another referring expresssion. Classifiers have the distribution typical of nouns: they may be a clausal subject, they may be modified by a relative clause, they may have a prepositional complement, and so forth. And classifiers head noun phrases, a claim for which various arguments are given, among them one based on the remarkable similarity between the host-classifier and possessor-possessed constructions