Generalized submersiveness of second-order ordinary differential equations

We generalize the notion of submersive second-order differential equations by relaxing the condition that the decoupling stems from the tangent lift of a basic distribution. It is shown that this leads to adapted coordinates in which a number of first-order equations decouple from the remaining second-order ones

Triple-wavelength fiber ring laser based on a hybrid gain medium actively mode-locked at 10 GHz

A fiber ring laser based on a hybrid gain medium that produces three simultaneously mode-locked wavelength channels is presented. The lithium niobate based modulator used to actively mode-lock the laser cavity at 10 GHz is birefringence compensated to reduce its polarization sensitivity. A Lyot filter defines the lasers multiwavelength spectrum which has a wavelength spacing of 1 nm. The polarization sensitive nature of the laser cavity and its affect on the performance of the laser is discussed

Numerical analysis of pulse pedestal and dynamic chirp formation on picosecond modelocked laser pulses after propagation through a semiconductor optical amplifier

A numerical analysis, based on a modified Schrodinger equation, of the formation of pulse pedestals and dynamic chirp formation on picosecond pulses after propagation through a semiconductor optical amplifier is presented. The numerical predictions are confirmed by an experiment that utilises the frequency resolved optical gating technique for the amplified pulse characterisation

Two-photon-absorption-based OSNR monitor for NRZ-PSK transmission systems

A two-photon absorption microcavity-based technique for monitoring in-band optical signal-to-noise ratio (OSNR) in nonreturn-to-zero phase-shift-keying systems is presented. Experiments using a 10-Gb/s differential phase-shift-keying system showed that accurate measurements ( 1 dB) were possible for OSNRs in excess of 20 dB

Two dimensional dynamical systems which admit Lie and Noether symmetries

We prove two theorems which relate the Lie point symmetries and the Noether symmetries of a dynamical system moving in a Riemannian space with the special projective group and the homothetic group of the space respectively. The theorems are applied to classify the two dimensional Newtonian dynamical systems, which admit a Lie point/Noether symmetry. Two cases are considered, the non-conservative and the conservative forces. The use of the results is demonstrated for the Kepler - Ermakov system, which in general is non-conservative and for potentials similar to the H\`enon Heiles potential. Finally it is shown that in a FRW background with no matter present, the only scalar cosmological model which is integrable is the one for which 3-space is flat and the potential function of the scalar field is exponential. It is important to note that in all applications the generators of the symmetry vectors are found by reading the appropriate entry in the relevant tables.Comment: 25 pages, 17 table

Risk factors for polyoma virus nephropathy

Background. Polyoma virus-associated nephropathy (PVN) is a common cause of renal transplant failure. The risk factors for the development of PVN have not yet been studied in large cohorts of patients for periods of 20 years. Methods. We collected clinical, renal biopsy and urinary cytology data from all patients with renal transplantations performed at the University Hospital of Basel from 1985 to 2005. All patients with a renal biopsy and urine cytology were included (n = 880). Renal transplants were divided into three groups, according to evidence of polyoma virus (PV) infection (decoy cells in the urine) and biopsy-proven PVN: Renal transplants without evidence of a PV infection (n = 751). Renal transplants with PV reactivation, e.g. decoy cell (DC) found by urinary cytology, but without PVN (n = 90). Renal transplants with PVN (n = 39). Results. The prevalence of biopsy-proven PVN in this cohort of patients was 3.3%. Immunosuppression with mycophenolate and/or tacrolimus, ATGAM, male gender of the recipient and a higher number of transplant rejection episodes were factors significantly associated with PVN development. Conclusions. The most important risk factors for the development of PVN are acute rejection and ATGAM used as induction therapy as well as tacrolimus and mycophenolate as maintenance therapy. Therefore, we conclude that patients with tacrolimus and mycophenolate maintenance therapy should be carefully monitored for the development of PV

Whole-Genome Sequencing and Concordance Between Antimicrobial Susceptibility Genotypes and Phenotypes of Bacterial Isolates Associated with Bovine Respiratory Disease.

Extended laboratory culture and antimicrobial susceptibility testing timelines hinder rapid species identification and susceptibility profiling of bacterial pathogens associated with bovine respiratory disease, the most prevalent cause of cattle mortality in the United States. Whole-genome sequencing offers a culture-independent alternative to current bacterial identification methods, but requires a library of bacterial reference genomes for comparison. To contribute new bacterial genome assemblies and evaluate genetic diversity and variation in antimicrobial resistance genotypes, whole-genome sequencing was performed on bovine respiratory disease-associated bacterial isolates (Histophilus somni, Mycoplasma bovis, Mannheimia haemolytica, and Pasteurella multocida) from dairy and beef cattle. One hundred genomically distinct assemblies were added to the NCBI database, doubling the available genomic sequences for these four species. Computer-based methods identified 11 predicted antimicrobial resistance genes in three species, with none being detected in M. bovis While computer-based analysis can identify antibiotic resistance genes within whole-genome sequences (genotype), it may not predict the actual antimicrobial resistance observed in a living organism (phenotype). Antimicrobial susceptibility testing on 64 H. somni, M. haemolytica, and P. multocida isolates had an overall concordance rate between genotype and phenotypic resistance to the associated class of antimicrobials of 72.7% (P < 0.001), showing substantial discordance. Concordance rates varied greatly among different antimicrobial, antibiotic resistance gene, and bacterial species combinations. This suggests that antimicrobial susceptibility phenotypes are needed to complement genomically predicted antibiotic resistance gene genotypes to better understand how the presence of antibiotic resistance genes within a given bacterial species could potentially impact optimal bovine respiratory disease treatment and morbidity/mortality outcomes

Long-term Periodicities of Cataclysmic Variables with Synoptic Surveys

A systematic study on the long-term periodicities of known Galactic cataclysmic variables (CVs) was conducted. Among 1580 known CVs, 344 sources were matched and extracted from the Palomar Transient Factory (PTF) data repository. The PTF light curves were combined with the Catalina Real-Time Transient Survey (CRTS) light curves and analyzed. Ten targets were found to exhibit long-term periodic variability, which is not frequently observed in the CV systems. These long-term variations are possibly caused by various mechanisms, such as the precession of the accretion disk, hierarchical triple star system, magnetic field change of the companion star, and other possible mechanisms. We discuss the possible mechanisms in this study. If the long-term period is less than several tens of days, the disk precession period scenario is favored. However, the hierarchical triple star system or the variations in magnetic field strengths are most likely the predominant mechanisms for longer periods.Comment: 33 pages, 9 figures (manuscript form), Accepted for publication in PAS

Autonomous three dimensional Newtonian systems which admit Lie and Noether point symmetries

We determine the autonomous three dimensional Newtonian systems which admit Lie point symmetries and the three dimensional autonomous Newtonian Hamiltonian systems, which admit Noether point symmetries. We apply the results in order to determine the two dimensional Hamiltonian dynamical systems which move in a space of constant non-vanishing curvature and are integrable via Noether point symmetries. The derivation of the results is geometric and can be extended naturally to higher dimensions.Comment: Accepted for publication in Journal of Physics A: Math. and Theor.,13 page

Zwicky Transient Facility constraints on the optical emission from the nearby repeating FRB 180916.J0158+65

The discovery rate of fast radio bursts (FRBs) is increasing dramatically thanks to new radio facilities. Meanwhile, wide-field instruments such as the 47 deg$^2$ Zwicky Transient Facility (ZTF) survey the optical sky to study transient and variable sources. We present serendipitous ZTF observations of the CHIME repeating source FRB 180916.J0158+65, that was localized to a spiral galaxy 149 Mpc away and is the first FRB suggesting periodic modulation in its activity. While 147 ZTF exposures corresponded to expected high-activity periods of this FRB, no single ZTF exposure was at the same time as a CHIME detection. No $>3\sigma$ optical source was found at the FRB location in 683 ZTF exposures, totalling 5.69 hours of integration time. We combined ZTF upper limits and expected repetitions from FRB 180916.J0158+65 in a statistical framework using a Weibull distribution, agnostic of periodic modulation priors. The analysis yielded a constraint on the ratio between the optical and radio fluences of $\eta \lesssim 200$, corresponding to an optical energy $E_{\rm opt} \lesssim 3 \times 10^{46}$ erg for a fiducial 10 Jy ms FRB (90% confidence). A deeper (but less statistically robust) constraint of $\eta \lesssim 3$ can be placed assuming a rate of $r(>5$ Jy ms)= hr$^{-1}$ and $1.2\pm 1.1$ FRB occurring during exposures taken in high-activity windows. The constraint can be improved with shorter per-image exposures and longer integration time, or observing FRBs at higher Galactic latitudes. This work demonstrated how current surveys can statistically constrain multi-wavelength counterparts to FRBs even without deliberately scheduled simultaneous radio observation.Comment: Accepted for publication in ApJL, 9 pages, 4 figures, 1 tabl