A Single-Year Cosmic Ray Event at 5410 BCE Registered in 14C of Tree Rings.

The annual 14C data in tree rings is an outstanding proxy for uncovering extreme solar energetic particle (SEP) events in the past. Signatures of extreme SEP events have been reported in 774/775 CE, 992/993 CE, and ∼660 BCE. Here, we report another rapid increase of 14C concentration in tree rings from California, Switzerland, and Finland around 5410 BCE. These 14C data series show a significant increase of ∼6‰ in 5411-5410 BCE. The signature of 14C variation is very similar to the confirmed three SEP events and points to an extreme short-term flux of cosmic ray radiation into the atmosphere. The rapid 14C increase in 5411/5410 BCE rings occurred during a period of high solar activity and 60 years after a grand 14C excursion during 5481-5471 BCE. The similarity of our 14C data to previous events suggests that the origin of the 5410 BCE event is an extreme SEP event.

Author Correction: Solar superstorm of AD 774 recorded subannually by Arctic tree rings.

The authors became aware of a mistake in the data displayed in Fig. 1 and Supplementary Table 2 of the original version of the Article. Specifically, the 14C production values were printed out in the code before the conversion between the omnidirectional fluence and the flux. As a consequence, the values of the 14C production in Fig. 1 and Supplementary Table 2 were too high by a factor of 4×π = 12.566.. As a result of this, a number of changes have been made to both the PDF and the HTML versions of the Article. A full list of these changes is available online.

Solar superstorm of AD 774 recorded subannually by Arctic tree rings.

Recently, a rapid increase in radiocarbon (14C) was observed in Japanese tree rings at AD 774/775. Various explanations for the anomaly have been offered, such as a supernova, a γ-ray burst, a cometary impact, or an exceptionally large Solar Particle Event (SPE). However, evidence of the origin and exact timing of the event remains incomplete. In particular, a key issue of latitudinal dependence of the 14C intensity has not been addressed yet. Here, we show that the event was most likely caused by the Sun and occurred during the spring of AD 774. Particularly, the event intensities from various locations show a strong correlation with the latitude, demonstrating a particle-induced 14C poleward increase, in accord with the solar origin of the event. Furthermore, both annual 14C data and carbon cycle modelling, and separate earlywood and latewood 14C measurements, confine the photosynthetic carbon fixation to around the midsummer.

A portable methane sampling system for radiocarbon-based bioportion measurements and environmental CH4 sourcing studies.

Radiocarbon measurements can be used to deduce the proportion of renewable to fossil carbon in materials. While these biofraction measurements are performed routinely on solid and liquid substances, measurements of gaseous samples, such as methane, are still scarce. As a pioneering effort, we have developed a field-capable sampling system for the selective capture of CH4 for radiocarbon-concentration measurements. The system allows for biofraction measurements of methane by accelerator mass spectrometry. In environmental research, radiocarbon measurements of methane can be used for fingerprinting different sources of methane emissions. In metrology and industry, biofraction measurements can be utilized to characterize biogas/natural gas mixtures within gas-line networks. In this work, the portable sampling system is described in detail and reference measurements of biofractions of gaseous fuel samples are presented. Low-concentration (1-ppm-CH4) sampling for environmental applications appears feasible but has not been fully tested at present. This development allows for multitude of future applications ranging from Arctic methane emissions to biogas insertion to gas networks.

Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes.

Various studies report substantial increases in intrinsic water-use efficiency (W i ), estimated using carbon isotopes in tree rings, suggesting trees are gaining increasingly more carbon per unit water lost due to increases in atmospheric CO2. Usually, reconstructions do not, however, correct for the effect of intrinsic developmental changes in W i as trees grow larger. Here we show, by comparing W i across varying tree sizes at one CO2 level, that ignoring such developmental effects can severely affect inferences of trees' W i . W i doubled or even tripled over a trees' lifespan in three broadleaf species due to changes in tree height and light availability alone, and there are also weak trends for Pine trees. Developmental trends in broadleaf species are as large as the trends previously assigned to CO2 and climate. Credible future tree ring isotope studies require explicit accounting for species-specific developmental effects before CO2 and climate effects are inferred.Intrinsic water-use efficiency (W i ) reconstructions using tree rings often disregard developmental changes in W i as trees age. Here, the authors compare W i across varying tree sizes at a fixed CO2 level and show that ignoring developmental changes impacts conclusions on trees' W i responses to CO2 or climate.

How do academic health centers value and encourage clinical research?

To investigate whether there is a misalignment of the perceived values of and incentives for clinical research within U.S. academic health centers (AHCs), in 1999 the authors surveyed medical school deans, academic administrators, department chairs, and faculty members at 80 AHCs that are the members of the University HealthSystem Consortium, a not-for-profit consortium of AHCs. A total of 358 faculty from 58% of the institutions surveyed responded, with a mean of 3.76 responses/institution. There was general agreement that clinical research offers AHCs a considerable spectrum of benefits, including prestige, recruitment and retention of faculty, criteria for promotion of faculty, and financial support. Investigator-initiated research and government-funded research ranked highest in terms of their desirability compared with industry-sponsored and contract research. This preference was agreed upon across all categories of respondents and types of research (translational, clinical tests, and outcomes). Significant differences existed between the perceptions of deans/AHC administrators, who stated that they were increasing their emphasis on clinical investigation in the areas of research space (56% of responders), administrative support (81%), and patient recruitment (61%) and the perceptions of their departmental chairs/faculties in the same areas (34%, 52%, and 40%, respectively; p <.05). Faculty opinions documented few new investments in the actual infrastructure dedicated to clinical research. The authors conclude that their findings, which they consider reasonably representative, strongly suggest that the value of clinical research to AHCs is well understood. Their findings also identify important opportunities for AHCs to provide a wider range of incentives for the conduct of clinical research.

Coulomb excitation of 68,70Cu: first use of postaccelerated isomeric beams.

We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. Gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2 nu 1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N approximately 40.

First precision mass measurements of refractory fission fragments.

Atomic masses of 95-100Sr, 98-105Zr, and [corrected] 102-110Mo and have been measured with a precision of 10 keV employing a Penning trap setup at the IGISOL facility. Masses of 104,105Zr and 109,110Mo are measured for the first time. Our improved results indicate significant deviations from the previously published values deduced from beta end point measurements. The most neutron-rich studied isotopes are found to be significantly less bound (1 MeV) compared to the 2003 atomic mass evaluation. A strong correlation between nuclear deformation and the binding energy is observed in the two-neutron separation energy in all studied isotope chains.

"Safe" Coulomb excitation of 30Mg.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."

National data sources on the care and outcomes of patients with community acquired pneumonia.

Despite improved understanding and treatment of community acquired pneumonia (CAP), variations in clinical practice and patient outcomes still exists, resulting in excess healthcare dollars spent and decreased patient satisfaction. The use of treatment and outcomes research data can help providers improve their methods and standardize techniques to control costs and provide the best care for their patients. To better understand the utility and capabilities of this research, this article will compare several administrative and clinical databases. Two, data sources in particular, the EPI-Q Inc. CAP-Compare database and the University HealthSystem Consortium's (UHC) CAP Benchmarking Program contain clinical and utilization data specific to CAP. In addition there are several government and non-government sponsored data sources that include administrative data on many diagnosis including CAP. These include: Healthcare Benchmarking Systems International's EXPLORE database, the Center for Healthcare Industry Performance Studies database, the National Center for Health Statistics'--National Hospital Discharge Survey, and the Medicare Provider Analysis and Review data files.

Clinical and economic outcomes of coronary angioplasty alone or in combination with stents in academic health centers: a retrospective database analysis.

OBJECTIVES: Indications for the use of stents are evolving and their optimal place in therapy remains to be defined. The objective was to compare the 1-year clinical and economic outcomes of percutaneous transluminal coronary agioplasty (PTCA) with and without the use of stents. METHODS: This retrospective database analysis was conducted using data from 60 US academic medical centers in 1996 and 1997. Outcomes of interest included in-hospital mortality (both on sentinel and readmission visits), readmission rates, revascularization procedures, length of stay, and the cost of sentinel and readmission hospitalization. RESULTS: A total of 27,020 patients either did (n = 13,254) or did not (n = 13,766) receive coronary stents in conjunction with PTCA. The median cost of hospitalization for the stent group was about dollar 1,409 higher (mean, dollar 1,200) than the no-stent group and the length of stay was similar (4.3 days vs. 4.5 days, respectively, P = .2628). Mortality rates on readmission (0.9% stent vs. 0.8% no-stent, P = NS) did not differ. However, patients in the stent group had better mortality rates compared to the no-stent group during the sentinel visit (1.7% vs. 2.7%, P < .001). Stent use was not associated with a significantly lower risk of a revascularization procedure on readmission to the same institution (OR 0.95, 95% CI 0.87-1.04, P = .28). CONCLUSIONS: Stents were associated with a 1% decrease of inpatient mortality during the sentinel visit without impacting length of stay or readmission rates. This advantage was associated with a dollar 1,409 higher median cost of hospitalization in the stent group.

Risk of breast cancer among female teachers of physical education and languages.

A retrospective follow-up study on 924 physical education (PE) and 3,239 language (L) teachers was performed to study whether life-long high physical activity affects the risk of breast cancer. The Finnish Cancer Registry found 128 malignant breast cancers among these women in a follow-up during 1967-1987. The standardized incidence ratio (SIR) for all PE teachers was 1.28 (n.s.) and for L teachers 1.59 (p less than 0.001). Before the menopause (below age 50) SIR for PE teachers was 0.93 (n.s.) and for L teachers 1.51 (p less than 0.05). These results suggest that before menopause the risk of breast cancer in physically active PE is smaller than in the less active L. A Poisson regression analysis, taking into account the reproductive factors together with age and observation period, did not show any significant difference between PE and L teachers, probably due to the relatively small number of cases (n = 22) in the PE teacher group.

Mass measurement on the rp-process waiting point 72Kr.

The mass of one of the three major waiting points in the astrophysical rp process 72Kr was measured for the first time with the Penning trap mass spectrometer ISOLTRAP. The measurement yielded a relative mass uncertainty of deltam/m=1.2x10(-7) (deltam=8 keV). (73,74)Kr, also needed for astrophysical calculations, were measured with more than 1 order of magnitude improved accuracy. We use the ISOLTRAP masses of 72-74Kr to reanalyze the role of 72Kr (T(1/2)=17.2 s) in the rp process during x-ray bursts and conclude that 72Kr is a strong waiting point delaying the burst duration with at least 80% of its beta-decay half-life.