Emittance and lifetime measurement with damping wigglers.

National Synchrotron Light Source II (NSLS-II) is a new third-generation storage ring light source at Brookhaven National Laboratory. The storage ring design calls for small horizontal emittance (<1 nm-rad) and diffraction-limited vertical emittance at 12 keV (8 pm-rad). Achieving low value of the beam size will enable novel user experiments with nm-range spatial and meV-energy resolution. The high-brightness NSLS-II lattice has been realized by implementing 30-cell double bend achromatic cells producing the horizontal emittance of 2 nm rad and then halving it further by using several Damping Wigglers (DWs). This paper is focused on characterization of the DW effects in the storage ring performance, namely, on reduction of the beam emittance, and corresponding changes in the energy spread and beam lifetime. The relevant beam parameters have been measured by the X-ray pinhole camera, beam position monitors, beam filling pattern monitor, and current transformers. In this paper, we compare the measured results of the beam performance with analytic estimates for the complement of the 3 DWs installed at the NSLS-II.

Newly identified respiratory viruses associated with acute lower respiratory tract infections in children in Lanzou, China, from 2006 to 2009.

Nasopharyngeal aspirates were collected from 813 children ≤ 14 years old with acute lower respiratory tract infections in Lanzhou, China, from December 2006 to November 2009. PCR or RT-PCR was used to screen for the presence of 10 respiratory viruses. Viral agents were identified in 73.92% (601/813) of specimens, including RSV in 40.71%, hMPV in 6.15%, IFVA in 7.13%, IFVB in 0.98%, PIV1-3 in 7.87%, HCoV-HKU1 in 2.21%, HCoV-NL63 in 3.81%, HRV in 19.93%, AdV in 7.50% and HBoV in 11.56%. Two or more viruses were detected in 34.44% (280/813) of cases. The newly identified respiratory viruses, HBoV, hMPV, HCoV-HKU1 and HCoV-NL63, accounted for 22.01% of the detected viral pathogens. RSV and HRV were frequently detected in patients with bronchiolitis, and hMPV was frequently associated with pneumonia. HCoV-NL63 was found to be one of the causative agents of acute respiratory wheezing in young children. No seasonal variation was found in the incidence of detection of HCoV-HKU1, HCoV-NL63 or HBoV. This 3-year study demonstrated that viral pathogens play an important role in children with ALRTIs, and more attention should be paid to these newly identified viral agents.

Prevalence of human parechovirus in Chinese children hospitalized for acute gastroenteritis.

Human parechoviruses (HPeVs) are widespread pathogens causing a wide spectrum of diseases. HPeVs belong to the family Picornaviridae, and 14 genotypes are known. We conducted a case-control study to investigate the role of HPeV in acute gastroenteritis. HPeV was detected and quantified using real-time RT-PCR, and then genotyped by sequencing of the nested RT-PCR product of the VP3/VP1 partial gene. HPeV was found in both the case and control groups (29.4% and 15.3% respectively, p 0.006). Six HPeV genotypes (HPeV1, HPeV3, HPeV4, HPeV5, HPeV6, and HPeV8) were detected. Nine positive samples could not be sequenced with negative genotyped RT-PCR. HPeV1 and HPeV3 were the most prevalent genotypes, and co-infection was common in the case group. No statistically significant differences in either viral load or the rate of HPeV1 and HPeV3 infection were found between the two groups. Additionally, no significant differences were found in fever rates, vomiting rates or mean duration and frequency of diarrhoea and vomiting between the positive and negative case groups with HPeV1 or HPeV3. Multivariate logistic regression analysis indicated that there was no association between the HPeV1 or HPeV3 infection and acute gastroenteritis. Multiple genotypes of HPeVs were highly prevalent in Chinese children. One potential new HPeV genotype was identified, but needs to be confirmed further by the picoma study group. However, the present study does not support a causative role of HPeV1 and HPeV3 in acute gastroenteritis.