Isotope shifts and hyperfine structure of the Fe I 372 nm resonance line

We report measurements of the isotope shifts of the $3d^64s^2 a ^5D_4 - 3d^64s4p z ^5F_5^o$ Fe I resonance line at 372 nm between all four stable isotopes $^{54}$Fe, $^{56}$Fe, $^{57}$Fe, and $^{58}$Fe, as well as the complete hyperfine structure of that line for $^{57}$Fe, the only stable isotope having a non-zero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant $A$ of the excited state of the transition in $^{57}$Fe: $A(3d^64s4p z ^5F_5^o) = 81.69(86)$ MHz. The measurements were done by means of Doppler-free laser saturated-absorption spectroscopy in a Fe-Ar hollow cathode using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.Comment: 5 pages, 5 figure

Super-resolving multi-photon interferences with independent light sources

We propose to use multi-photon interferences from statistically independent light sources in combination with linear optical detection techniques to enhance the resolution in imaging. Experimental results with up to five independent thermal light sources confirm this approach to improve the spatial resolution. Since no involved quantum state preparation or detection is required the experiment can be considered an extension of the Hanbury Brown and Twiss experiment for spatial intensity correlations of order N>2

Determinants, outcomes and costs of ceftriaxone v. amoxicillin-clavulanate in the treatment of community-acquired pneumonia at Witbank Hospital

BACKGROUND. Community-acquired pneumonia (CAP) is a major cause of death and morbidity worldwide. Treatment is centred on antibiotics with ceftriaxone and amoxicillin-clavulanate being some of the most commonly prescribed agents. Objective. To compare treatment outcomes and costs in patients receiving either of these two antibiotics at Witbank Hospital (WH). METHODS. A total of 200 randomly selected adult patient files (100 receiving ceftriaxone and 100 amoxicillin-clavulanate) recording a diagnosis of CAP were studied to determine the length of hospital stay, comorbid conditions and treatment outcomes. A descriptive and comparable analysis was performed. RESULTS. Male gender, higher CURB-65 scores and death were associated with the use of ceftriaxone. Severity of disease and previous antibiotic exposure influenced the duration of hospital admission. CONCLUSION. Gender and severity of disease (based on the CURB-65 score) were the determinants of antibiotic choice at WH. Male gender increased the likelihood of being treated with ceftriaxone, as did a CURB-65 score of >2. There were no differences in the outcomes of CAP patients treated with ceftriaxone compared with those treated with amoxicillin-clavulanate. Irrespective of antibiotic used, gender and severity of disease influenced treatment outcomes. Male gender was associated with a higher mortality and longer hospital stay. The average duration of stay for both antibiotics was not significantly different. Thus, only level 1 and 2 costs need to be considered when comparing the two regimens. On this basis, ceftriaxone was cheaper than amoxicillin-clavulanate.http://www.samj.org.zaam201

Direct evidence of a prey depletion "halo" surrounding a pelagic predator colony

Colonially breeding birds and mammals form some of the largest gatherings of apex predators in the natural world and have provided model systems for studying mechanisms of population regulation in animals. According to one influential hypothesis, intense competition for food among large numbers of spatially constrained foragers should result in a zone of prey depletion surrounding such colonies, ultimately limiting their size. However, while indirect and theoretical support for this phenomenon, known as "Ashmole's halo," has steadily accumulated, direct evidence remains exceptionally scarce. Using a combination of vesselbased surveys and Global Positioning System tracking, we show that pelagic seabirds breeding at the tropical island that first inspired Ashmole's hypothesis do indeed deplete their primary prey species (flying fish; Exocoetidae spp.) over a considerable area, with reduced prey density detectable >150 km from the colony. The observed prey gradient was mirrored by an opposing trend in seabird foraging effort, could not be explained by confounding environmental variability, and can be approximated using a mechanistic consumption-dispersion model, incorporating realistic rates of seabird predation and random prey dispersal. Our results provide a rare view of the resource footprint of a pelagic seabird colony and reveal how aggregations of these central-place foraging, marine top predators profoundly influence the oceans that surround them