An implementation and analysis of the Abstract Syntax Notation One and the basic encoding rules

The details of abstract syntax notation one standard (ASN.1) and the basic encoding rules standard (BER) that collectively solve the problem of data transfer across incompatible host environments are presented, and a compiler that was built to automate their use is described. Experiences with this compiler are also discussed which provide a quantitative analysis of the performance costs associated with the application of these standards. An evaluation is offered as to how well suited ASN.1 and BER are in solving the common data representation problem

Experience with abstract notation one

The development of computer science has produced a vast number of machine architectures, programming languages, and compiler technologies. The cross product of these three characteristics defines the spectrum of previous and present data representation methodologies. With regard to computer networks, the uniqueness of these methodologies presents an obstacle when disparate host environments are to be interconnected. Interoperability within a heterogeneous network relies upon the establishment of data representation commonality. The International Standards Organization (ISO) is currently developing the abstract syntax notation one standard (ASN.1) and the basic encoding rules standard (BER) that collectively address this problem. When used within the presentation layer of the open systems interconnection reference model, these two standards provide the data representation commonality required to facilitate interoperability. The details of a compiler that was built to automate the use of ASN.1 and BER are described. From this experience, insights into both standards are given and potential problems relating to this development effort are discussed

Development of primary invasive pneumococcal disease caused by serotype 1 pneumococci is driven by early increased type I interferon response in the lung

The pneumococcus is the world's foremost respiratory pathogen, but the mechanisms allowing this pathogen to proceed from initial asymptomatic colonization to invasive disease are poorly understood. We have examined the early stages of invasive pneumococcal disease (IPD) by comparing host transcriptional responses to an invasive strain and a noninvasive strain of serotype 1 Streptococcus pneumoniae in the mouse lung. While the two strains were present in equal numbers in the lung 6 h after intranasal challenge, only the invasive strain (strain 1861) had invaded the pleural cavity at that time point; this correlated with subsequent development of bacteremia in mice challenged with strain 1861 but not the noninvasive strain (strain 1). Progression beyond the lung was associated with stronger induction of the type I interferon (IFN-I) response in the lung at 6 h. Suppression of the IFN-I response through administration of neutralizing antibody to IFNAR1 (the receptor for type I interferons) led to significantly reduced invasion of the pleural cavity by strain 1861 at 6 h postchallenge. Our data suggest that strong induction of the IFN-I response is a key factor in early progression of invasive serotype 1 strain 1861 beyond the lung during development of IPD

Does the World Need U.S. Farmers Even if Americans Don’t?

We consider the implications of trends in the number of U.S. farmers and food imports on the question of what role U.S. farmers have in an increasingly global agrifood system. Our discussion stems from the argument some scholars have made that American consumers can import their food more cheaply from other countries than it can produce it. We consider the distinction between U.S. farmers and agriculture and the effect of the U.S. food footprint on developing nations to argue there might be an important role for U.S. farmers, even if it appears Americans don’t need them. For instance, we may need to protect U.S. farmland and, by implication, U.S. farmers, for future food security needs both domestic and international. We also explore the role of U.S. farmers by considering the question of whether food is a privilege or a right. Although Americans seem to accept that food is a privilege, many scholars and commentators argue that, at least on a global scale, food is a right, particularly for the world’s poor and hungry. If this is the case, then U.S. farmers might have a role in meeting the associated obligation to ensure that the poor of the world have enough food to eat. We look at the consequences of determining that food is a right versus a privilege and the implications of that decision for agricultural subsidies as well as U.S. agriculture and nutrition policies.Food Security and Poverty,

Does the World Need U.S. Farmers Even if Americans Don't?

We consider the implications of trends in the number of U.S. farmers and food imports on the question of what role U.S. farmers have in an increasingly global agrifood system. Our discussion stems from the argument some scholars have made that American consumers can import their food more cheaply from other countries than it can produce it. We consider the distinction between U.S. farmers and agriculture and the effect of the U.S. food footprint on developing nations to argue there might be an important role for U.S. farmers, even if it appears Americans don't need them. For instance, we may need to protect U.S. farmland and, by implication, U.S. farmers, for future food security needs both domestic and international. We also explore the role of U.S. farmers by considering the question of whether food is a privilege or a right. Although Americans seem to accept that food is a privilege, many scholars and commentators argue that, at least on a global scale, food is a right, particularly for the world's poor and hungry. If this is the case, then U.S. farmers might have a role in meeting the associated obligation to ensure that the poor of the world have enough food to eat. We look at the consequences of determining that food is a right versus a privilege and the implications of that decision for agricultural subsidies as well as U.S. agriculture and nutrition policies

Overlapping functionality of the Pht proteins in zinc homeostasis of streptococcus pneumoniae

Streptococcus pneumoniae is a globally significant pathogen that causes a range of diseases, including pneumonia, sepsis, meningitis, and otitis media. Its ability to cause disease depends upon the acquisition of nutrients from its environment, including transition metal ions such as zinc. The pneumococcus employs a number of surface proteins to achieve this, among which are four highly similar polyhistidine triad (Pht) proteins. It has previously been established that these proteins collectively aid in the delivery of zinc to the ABC transporter substrate-binding protein AdcAII. Here we have investigated the contribution of each individual Pht protein to pneumococcal zinc homeostasis by analyzing mutant strains expressing only one of the four pht genes. Under conditions of low zinc availability, each of these mutants showed superior growth and zinc accumulation profiles relative to a mutant strain lacking all four genes, indicating that any of the four Pht proteins are able to facilitate delivery of zinc to AdcAII. However, optimal growth and zinc accumulation in vitro and pneumococcal survival and proliferation in vivo required production of all four Pht proteins, indicating that, despite their overlapping functionality, the proteins are not dispensable without incurring a fitness cost. We also show that surface-attached forms of the Pht proteins are required for zinc recruitment and that they do not contribute to defense against extracellular zinc stress

The first histidine triad motif of phtd is critical for zinc homeostasis in Streptococcus pneumoniae

Streptococcus pneumoniae is the world's foremost human pathogen. Acquisition of the first row transition metal ion zinc is essential for pneumococcal colonization and disease. Zinc is acquired via the ATP-binding cassette transporter AdcCB and two zinc-binding proteins, AdcA and AdcAII. We have previously shown that AdcAII is reliant upon the polyhistidine triad (Pht) proteins to aid in zinc recruitment. Pht proteins generally contain five histidine (His) triad motifs that are believed to facilitate zinc binding and therefore play a significant role in pneumococcal metal ion homeostasis. However, the importance and potential redundancy of these motifs have not been addressed. We examined the effects of mutating each of the five His triad motifs of PhtD. The combination of in vitro growth assays, active zinc uptake, and PhtD expression studies show that the His triad closest to the protein's amino terminus is the most important for zinc acquisition. Intriguingly, in vivo competitive infection studies investigating the amino- and carboxyl-terminal His triad mutants indicate that the motifs have similar importance in colonization. Collectively, our new insights into the contributions of the individual His triad motifs of PhtD, and by extension the other Pht proteins, highlight the crucial role of the first His triad site in zinc acquisition. This study also suggests that the Pht proteins likely play a role beyond zinc acquisition in pneumococcal virulence

First Science Results From SOFIA/FORCAST: Super-Resolution Imaging of the S140 Cluster at 37\micron

We present 37\micron\ imaging of the S140 complex of infrared sources centered on IRS1 made with the FORCAST camera on SOFIA. These observations are the longest wavelength imaging to resolve clearly the three main sources seen at shorter wavelengths, IRS 1, 2 and 3, and are nearly at the diffraction limit of the 2.5-m telescope. We also obtained a small number of images at 11 and 31\micron\ that are useful for flux measurement. Our images cover the area of several strong sub-mm sources seen in the area -- SMM 1, 2, and 3 -- that are not coincident with any mid-infrared sources and are not visible in our longer wavelength imaging either. Our new observations confirm previous estimates of the relative dust optical depth and source luminosity for the components in this likely cluster of early B stars. We also investigate the use of super-resolution to go beyond the basic diffraction limit in imaging on SOFIA and find that the van Cittert algorithm, together with the "multi-resolution" technique, provides excellent results

A note using mergers and acquisitions to gain competitive advantage in the United States in the case of Latin American MNCs

Author's OriginalThe "new" economic and business climate in Latin America, fostered by multilateral trade agreements such as NAFTA, MERCOSUR, and the ANDEAN Pact, suggests that Latin American (LA) firms must become more aggressive and competitive in order to survive. Foreign direct investment in the form of mergers and acquisitions (M&A) is often an effective way of competing in a tough global environment. Using transactions data collected from Security Data Company's Worldwide Merger and Acquisition database, this paper analyzes the relative involvement of firms from five LA countries (Argentina, Brazil, Chile, Mexico, and Venezuela) in acquiring targets in the United States of America. Transaction characteristics examined and summarized include the annual distribution (1985-1998) of the deals, the industrial sector of the target firm, the form of acquisition method used, and the form of ownership of the target firm. The trends are analyzed, and implications for managers are indicated.Milman, C. D., D’Mello, J. P., Aybar, B., & Arbaláez, H. (2001). A note using mergers and acquisitions to gain competitive advantage in the United States in the case of Latin American MNCs. International Review of Financial Analysis, 10(3), 323-332. doi:10.1016/S1057-5219(01)00056-

Limits on Radio Continuum Emission from a Sample of Candidate Contracting Starless Cores

We used the NRAO Very Large Array to search for 3.6 cm continuum emission from embedded protostars in a sample of 8 nearby ``starless'' cores that show spectroscopic evidence for infalling motions in molecular emission lines. We detect a total of 13 compact sources in the eight observed fields to 5 sigma limiting flux levels of typically 0.09 mJy. None of these sources lie within 1' of the central positions of the cores, and they are all likely background objects. Based on an extrapolation of the empirical correlation between the bolometric luminosity and 3.6 cm luminosity for the youngest protostars, these null-detections place upper limits of ~0.1 L_sun (d/140pc)^2 on the luminosities of protostellar sources embedded within these cores. These limits, together with the extended nature of the inward motions inferred from molecular line mapping (Lee et al. 2001), are inconsistent with the inside-out collapse model of singular isothermal spheres and suggest a less centrally condensed phase of core evolution during the earliest stages of star formation.Comment: Accepted to the Astronomical Journal; 12 pages, 1 figur