Energy dependent Schrödinger operators and complex Hamiltonian systems on Riemann surfaces

We use so-called energy-dependent Schrödinger operators to establish a link between special classes of solutions on N-component systems of evolution equations and finite dimensional Hamiltonian systems on the moduli spaces of Riemann surfaces. We also investigate the phase-space geometry of these Hamiltonian systems and introduce deformations of the level sets associated to conserved quantities, which results in a new class of solutions with monodromy for N-component systems of PDEs. After constructing a variety of mechanical systems related to the spatial flows of nonlinear evolution equations, we investigate their semiclassical limits. In particular, we obtain semicalssical asymptotics for the Bloch eigenfunctions of the energy dependent Schrödinger operators, which is of importance in investigating zero-dispersion limits of N-component systems of PDEs

Dispersion engineered As2S3 planar waveguides for broadband four-wave mixing based wavelength conversion of 40 Gb/s signals

We demonstrate broadband wavelength conversion of a 40 Gb/s return-to-zero signal using four-wave-mixing (FWM) in a dispersion engineered chalcogenide glass waveguide. The 6 cm long planar rib waveguide 2 μm wide was fabricated in a 0.87 μm thick film etched 350nm deep to correspond to a design where waveguide dispersion offsets the material leading to near-zero dispersion in the C-band and broadband phase matched FWM. The reduced dimensions also enhance the nonlinear coefficient to 9800 W-1km-1 at 1550 nm enabling broadband conversion in a shorter device. In this work, we demonstrate 80 nm wavelength conversions with 1.65 dB of power penalty at a bit-error rate of 10-9. Spectral measurements and simulations indicate extended broadband operation is possible

The Complete Genome Sequence of Yersinia pseudotuberculosis IP31758, the Causative Agent of Far East Scarlet-Like Fever

The first reported Far East scarlet-like fever (FESLF) epidemic swept the Pacific coastal region of Russia in the late 1950s. Symptoms of the severe infection included erythematous skin rash and desquamation, exanthema, hyperhemic tongue, and a toxic shock syndrome. The term FESLF was coined for the infection because it shares clinical presentations with scarlet fever caused by group A streptococci. The causative agent was later identified as Yersinia pseudotuberculosis, although the range of morbidities was vastly different from classical pseudotuberculosis symptoms. To understand the origin and emergence of the peculiar clinical features of FESLF, we have sequenced the genome of the FESLF-causing strain Y. pseudotuberculosis IP31758 and compared it with that of another Y. pseudotuberculosis strain, IP32953, which causes classical gastrointestinal symptoms. The unique gene pool of Y pseudotuberculosis IP31758 accounts for more than 260 strain-specific genes and introduces individual physiological capabilities and virulence determinants, with a significant proportion horizontally acquired that likely originated from Enterobacteriaceae and other soil-dwelling bacteria that persist in the same ecological niche. The mobile genome pool includes two novel plasmids phylogenetically unrelated to all currently reported Yersinia plasmids. An icm/dot type IVB secretion system, shared only with the intracellular persisting pathogens of the order Legionellales, was found on the larger plasmid and could contribute to scarlatinoid fever symptoms in patients due to the introduction of immunomodulatory and immunosuppressive capabilities. We determined the common and unique traits resulting from genome evolution and speciation within the genus Yersinia and drew a more accurate species border between Y. pseudotuberculosis and Y. pestis. In contrast to the lack of genetic diversity observed in the evolutionary young descending Y. pestis lineage, the population genetics of Y. pseudotuberculosis is more heterogenous. Both Y. pseudotuberculosis strains IP31758 and the previously sequenced Y. pseudotuberculosis strain IP32953 have evolved by the acquisition of specific plasmids and by the horizontal acquisition and incorporation of different genetic information into the chromosome, which all together or independently seems to potentially impact the phenotypic adaptation of these two strains

Vacuolating cytotoxin and variants in Atg16L1 that disrupt autophagy promote Helicobacter pylori infection in humans

Peer reviewedPreprin

Multiple antimicrobial resistance in plague: An emerging public health risk

Antimicrobial resistance in Yersinia pestis is rare, yet constitutes a significant international public health and biodefense threat. In 1995, the first multidrug resistant (MDR) isolate of Y. pestis (strain IP275) was identified, and was shown to contain a self-transmissible plasmid (pIP1202) that conferred resistance to many of the antimicrobials recommended for plague treatment and prophylaxis. Comparative analysis of the DNA sequence of Y. pestis plasmid pIP1202 revealed a near identical IncA/C plasmid backbone that is shared by MDR plasmids isolated from Salmonella enterica serotype Newport SL254 and the fish pathogen Yersinia ruckeri YR71. The high degree of sequence identity and gene synteny between the plasmid backbones suggests recent acquisition of these plasmids from a common ancestor. In addition, the Y. pestis pIP1202-like plasmid backbone was detected in numerous MDR enterobacterial pathogens isolated from retail meat samples collected between 2002 and 2005 in the United States. Plasmid-positive strains were isolated from beef, chicken, turkey and pork, and were found in samples from the following states: California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York and Oregon. Our studies reveal that this common plasmid backbone is broadly disseminated among MDR zoonotic pathogens associated with agriculture. This reservoir of mobile resistance determinants has the potential to disseminate to Y. pestis and other human and zoonotic bacterial pathogens and therefore represents a significant public health concern

Rapid changes in the seasonal sea level cycle along the US Gulf coast from the late 20th century

Temporal variations of the seasonal sea level harmonics throughout the 20th and early 21st century along the United States Gulf coast are investigated. A significant amplification of the annual sea level cycle from the 1990s onward is found, with both lower winter and higher summer sea levels in the eastern Gulf. Ancillary data are used to build a set of multiple regression models to explore the mechanisms driving the decadal variability and recent increase in the annual cycle. The results suggest that changes in the air surface temperature toward warmer summers and colder winters and changes in mean sea level pressure explain most of the amplitude increase. The changes in the seasonal sea level cycle are shown to have almost doubled the risk of hurricane induced flooding associated with sea level rise since the 1990s for the eastern and north-eastern Gulf of Mexico coastlines

109th Congress

Environmental protection concerns span a wide variety of issues, including clean air, water quality, chemical security, and environmental aspects of other major issue areas, such as energy, transportation, disaster relief and cleanup, and defense. This report provides an overview of key environmental issues receiving attention in the 109th Congress

109th Congress

Environmental protection concerns span a wide variety of issues, including clear air, water quality, chemical security, and environmental aspects of other major issue areas, such as energy, transportation, disaster relief and cleanup, and defense. This report provides an overview of key environmental issues receiving attention in the 109th Congress. A number of environmental measures have been the subject of congressional activity, some of them as part of comprehensive bills and laws on broader subjects such as energy and transportation. Appropriations for the Environmental Protection Agency (EPA) affect many of the programs and issues discussed in this report