B(E2) upward arrow measurements for radioactive neutron-rich ge isotopes: reaching the N=50 closed shell

The B(E2;0(+)(1)-->2(+)(1)) values for the radioactive neutron-rich germanium isotopes (78,80)Ge and the closed neutron shell nucleus 82Ge were measured at the HRIBF using Coulomb excitation in inverse kinematics. These data allow a study of the systematic trend between the subshell closures at N=40 and 50. The B(E2) behavior approaching N=50 is similar to the trend observed for heavier isotopic chains. A comparison of the experimental results with a shell model calculation demonstrates persistence of the N=50 shell gap and a strong sensitivity of the B(E2) values to the effective interaction.

Direct mass measurements on the superallowed emitter 74Rb and its daughter 74Kr: isospin-symmetry-breaking correction for standard-model tests

The decay energy of the superallowed beta decay 74Rb(beta+)74Kr was determined by direct Penning trap mass measurements on both the mother and the daughter nuclide using the time-of-flight resonance technique and was found to be Q=10 416.8(4.5) keV. The exotic nuclide 74Rb, with a half-life of only 65 ms, is the shortest-lived nuclide on which a high-precision mass measurement in a Penning trap has been carried out. Together with existing data for the partial half-life as well as theoretical corrections, the decay energy yields a comparative half-life of Ft=3084(15) s for this decay, in agreement with the mean value for the series of the lighter nuclides from 10C to 54Co. Assuming conserved vector current, this result allows for an experimental determination of the isospin-symmetry-breaking correction deltaC.

Reduced occupancy of the deeply bound 0d(5/2) neutron state in 32Ar

The 9Be(32Ar, 31Ar)X reaction, leading to the 5/2+ ground state of a nucleus at the proton drip line, has a cross section of 10.4(13) mb at a beam energy of 65.1 MeV/nucleon. This translates into a spectroscopic factor that is only 24(3)% of that predicted by the many-body shell-model theory. We introduce refinements to the eikonal reaction theory used to extract the spectroscopic factor to clarify that this very strong reduction represents an effect of nuclear structure. We suggest that it reflects correlation effects linked to the high neutron separation energy (22.0 MeV) for this state.

New approach for measuring properties of rp-process nuclei

A new experimental approach was developed that can reduce the uncertainties in astrophysical rapid proton capture (rp) process calculations due to nuclear data. This approach utilizes neutron removal from a radioactive ion beam to populate the nuclear states of interest. Excited states were deduced by the gamma-decay spectra measured in a semiconductor Ge-detector array. In the first case studied, 33Ar, excited states were measured with uncertainties of several keV. The 2 orders of magnitude improvement in the uncertainty of the level energies resulted in a 3 orders of magnitude improvement in the uncertainty of the calculated 32Cl(p,gamma)33Ar rate that is critical to the modeling of the rp process. This approach has the potential to measure key properties of almost all interesting nuclei on the rp-process path.

Lowest excitations in 56Ti and the predicted N=34 shell closure

Recent experimental characterization of the subshell closure at N=32 in the Ca, Ti, and Cr isotones has stimulated shell-model calculations that indicated the possibility that the N=34 isotones of these same elements could exhibit characteristics of a shell closure, namely, a high energy for the first excited 2(+) level. To that end, we have studied the decay of 56Sc produced in fragmentation reactions and identified new gamma rays in the daughter N=34 isotone 56Ti. The first 2(+) level is found at an energy of 1127 keV, well below the expected position that would indicate the presence of an N=34 shell closure in 56Ti.

N=82 shell quenching of the classical r-process "waiting-point" nucleus 130Cd

First beta- and gamma-spectroscopic decay studies of the N=82 r-process "waiting-point" nuclide 130Cd have been performed at CERN/ISOLDE using the highest achievable isotopic selectivity. Several nuclear-physics surprises have been discovered. The first one is the unanticipatedly high energy of 2.12 MeV for the [pi g(9/2) multiply sign in circle nu g(7/2)] 1(+) level in 130In, which is fed by the main Gamow-Teller transition. The second surprise is the rather high Q(beta) value of 8.34 MeV, which is in agreement only with recent mass models that include the phenomenon of N=82 shell quenching. Possible implications of these new results on the formation of the A approximately 130 r-process abundance peak are presented.

New direct reaction: two-proton knockout from neutron-rich nuclei

The reaction 9Be(28Mg,26Ne+gamma)X has been studied at 82 MeV/nucleon together with two similar cases, 30Mg and 34Si. Strong evidence that the reactions are direct is offered by the parallel-momentum distributions of the reaction residues and by the inclusive cross sections. The pattern of the partial cross sections for 28Mg suggests the presence of correlations. A preliminary theoretical discussion based on eikonal reaction theory and the many-body shell model is presented. The reaction holds great promise for the study of neutron-rich nuclei.

Molecular epidemiology of human enterovirus 71 strains and recent outbreaks in the Asia-Pacific region: comparative analysis of the VP1 and VP4 genes

This study provides a comprehensive overview of the molecular epidemiology of human enterovirus 71 (HEV71) in the Asia-Pacific region from 1997 through 2002. Phylogenetic analysis of the VP4 and VP1 genes of recent HEV71 strains indicates that several genogroups of the virus have been circulating in the Asia-Pacific region since 1997. The first of these recent outbreaks, described in Sarawak (Malaysian Borneo) in 1997, was caused by genogroup B3. This outbreak was followed by large outbreaks in Taiwan in 1998, caused by genogroup C2, and in Perth (Western Australia) in 1999, where viruses belonging to genogroups B3 and C2 cocirculated. Singapore, Taiwan, and Sarawak had HEV71 epidemics in 2000, caused predominantly by viruses belonging to genogroup B4; however, large numbers of fatalities were observed only in Taiwan. HEV71 was identified during an epidemic of hand, foot and mouth disease in Korea; that epidemic was found to be due to viruses constituting a new genogroup, C3.

Two-proton radioactivity of 45Fe

In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus 45Fe has been studied. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon-strip detector. The decay-energy spectrum of 45Fe implants shows a distinct peak at (1.14+/-0.04) MeV with a half-life of T(1/2)=(4.7(+3.4)(-1.4)) ms. None of the events in this peak is in coincidence with beta particles. For a longer correlation interval, daughter decays of the two-proton daughter 43Cr can be observed after 45Fe implantation. The decay energy for 45Fe agrees nicely with several theoretical predictions for two-proton radioactivity.

The left-handed double helical nucleic acids

The conversion of right-handed dsDNA and dsRNA to the left-handed Z-conformation involves a reorganization of the nucleotides relative to each other. This conversion can be facilitated by the tight binding of a Z-conformation-specific protein domain from the editing enzyme dsRNA adenosine deaminase. This may influence the modification of both pre-mRNAs as well as some replicating RNA viruses.

Identification of the I(pi) = 10(+) Yrast rotational state in 24Mg

Spins and parities of high spin states above the particle-binding threshold in 24Mg were determined with a basis expansion technique using triple and quadruple angular correlations between alpha particles and gamma rays. The first unambiguous identification of a 10(+) state is reported. Located at 19.2(1) MeV, this state decays predominantly by alpha emission, although a candidate gamma-decay branch with a 5.927 MeV transition connecting this 10(+) level to the rotational 8(+) state at 13.2 MeV was identified as well. The corresponding gamma-alpha branching ratio is 7(3)x10(-4).

Magic numbers in exotic nuclei and spin-isospin properties of the NN interaction

The magic numbers in exotic nuclei are discussed, and their novel origin is shown to be the spin-isospin dependent part of the nucleon-nucleon interaction in nuclei. The importance and robustness of this mechanism is shown in terms of meson exchange, G-matrix, and QCD theories. In neutron-rich exotic nuclei, magic numbers such as N = 8, 20, etc. can disappear, while N = 6, 16, etc. arise, affecting the structure of the lightest exotic nuclei to nucleosynthesis of heavy elements.

Random versus realistic interactions for low-lying nuclear spectra

We compare the shell-model results for realistic interactions with those obtained for various ensembles of random matrix elements. We show that, although the quantum numbers of the ground states in the even-even nuclei have a high probability ( approximately 60%) to be J(pi)T = 0(+)0, the overlap of those states with the realistic wave functions is very small in average. The transition probabilities B(E2) predicted with random interactions are also too small. The presence of the regular pairing is shown to be a significant element of realistic physics not reproduced by random interactions.

The left-handed double helical nucleic acids

The conversion of right-handed dsDNA and dsRNA to the left-handed Z-conformation involves a reorganization of the nucleotides relative to each other. This conversion can be facilitated by the tight binding of a Z-conformation-specific protein domain from the editing enzyme dsRNA adenosine deaminase. This may influence the modification of both pre-mRNAs as well as some replicating RNA viruses.

Lack of transmission of mycobacterium abscessus among patients with cystic fibrosis attending a single clinic

We retrospectively analyzed 1062 respiratory specimens from 214 patients with cystic fibrosis, of whom 5 patients had 36 cultures positive for M. abscessus. Results of molecular typing demonstrated that each of these 5 patients carried a single unique strain (genotype), which suggests that it may not be necessary to segregate patients with CF who are colonized or infected with M. abscessus from those who are not.

Azithromycin-containing regimens for treatment of Mycobacterium avium complex lung disease

Ninety-two patients were assessable in 3 consecutive, open, noncomparative, prospective, controlled, single-center trials of the use of multidrug regimens that contain azithromycin for treating pulmonary Mycobacterium avium complex (MAC) disease. Azithromycin was provided at a dose of 300-600 mg per day with oral companion drugs administered daily (regimen A, 29 patients); 600 mg 3 times weekly (t.i.w.), with oral companion drugs administered daily (regimen B, 20 patients); and 600 mg (t.i.w.), with oral companion drugs administered t.i.w. (regimen C, 43 patients). All regimens included rifabutin (or rifampin) and ethambutol as companion drugs as well as initial streptomycin. Treatment success was defined as 12 months of negative cultures while on therapy. Treatment failure was defined as sputum culture positivity after at least 6 months of therapy. Of the patients in each regimen who reached study end points, 17 of 29 (59%) were in regimen A, 11 of 20 (55%) were in regimen B, and 28 of 43 (65%) were in regimen C met the treatment success criterion. There were no statistically significant differences in outcome between the 3 regimens. These studies demonstrate the effectiveness of daily and t.i.w. regimens containing azithromycin for treatment of MAC lung disease.

Challenges of recruitment: focus groups with research study recruiters

To rectify the historic lack of research on women's health and the exclusion of women from many significant clinical trials, regulations have been promulgated requiring the inclusion of women and minorities in research studies. Acknowledging that the National Institutes of Health (NIH) mandate has resulted in more inclusive research, the unintended consequences associated with implementation of these regulations must also be explored. While the requirements preclude the use of cost as a reason for excluding women and/or minorities, the additional funding necessary to recruit adequate numbers of study participants has not been provided. Consequently, study recruiters often face unacknowledged expectations and job pressures as they attempt to meet recruitment goals. While it is important to support the NIH mandate, the additional stress imposed upon research study recruiters must also be recognized. Focus groups with study recruiters from various backgrounds and types of research provide an understanding of the challenges recruiters face when attempting to recruit diverse populations of women into research, and provide an understanding of the impact of recruitment goals on study recruiters' job satisfaction.

Nosocomial outbreaks/pseudo-outbreaks caused by nontuberculous mycobacteria

Nosocomial outbreaks and pseudo-outbreaks caused by the nontuberculous mycobacteria (NTM) have been recognized for more than 20 years and continue to be a problem. Most of these outbreaks have involved the rapidly growing mycobacterial species Mycobacterium fortuitum and M. abscessus. The reservoir for these outbreaks is generally municipal and (often separate) hospital water supplies. These mycobacterial species and others are incredibly hardy, able to grow in municipal and distilled water, thrive at temperatures of 45 degrees C or above (M. xenopi and M. avium complex), and resist the activity of organomercurials, chlorine, 2% concentrations of formaldehyde and alkaline glutaraldehyde, and other commonly used disinfectants. Disease outbreaks usually involve sternal wound infections, plastic surgery wound infections, or postinjection abscesses. Pseudo-outbreaks most commonly relate to contaminated bronchoscopes and endoscopic cleaning machines (M. abscessus) and contaminated hospital water supplies (M. xenopi). Knowledge of the reservoir of these species, their great survival capabilities within the hospital, and newer molecular techniques for strain comparison have helped control and more quickly identify current nosocomial outbreaks or pseudo-outbreaks caused by the NTM.

Headache as the sole presentation of acute myocardial infarction in two elderly patients

Myocardial infarction presenting solely as an acute, severe headache is underdiagnosed in elderly patients. In patients over 80 years of age, myocardial infarction presents more commonly with atypical symptoms than with chest pain. The authors describe two patients who presented with headache as the only symptom of an acute myocardial infarction. The authors recommend that acute myocardial infarction be considered in the differential diagnosis of acute, severe headache in elderly patients.

Effective steroid-sparing treatment for peripheral ulcerative keratitis and pyoderma gangrenosum

OBJECTIVE

To report a patient with a rare clinical presentation of marginal keratitis and pyoderma gangrenosum (PG) that responded to the steroid-sparing agent azathioprine.

DESIGN

Interventional case report.

METHODS

Case report and MEDLINE review of the medical literature on PG-associated peripheral ulcerative keratitis (PUK) and its treatment.

RESULTS

A patient with a biopsy-proven history of PG developed an explosive episode of PUK. The ocular inflammation was minimally responsive to topical therapy and required significant long-term oral steroids for control. The patient's active skin lesions and marginal keratitis responded dramatically to systemic oral azathioprine. Since the initiation of treatment with azathioprine, there have been no subsequent recurrences of PG or marginal keratitis.

CONCLUSIONS

PUK may be associated with other inflammatory conditions, such as PG and arthritis. Systemic azathioprine may successfully control ocular and extraocular conditions and should be considered in the clinical setting of topical therapy failure and/or extraocular inflammatory conditions.

MRI Artifact Masquerading as Orbital Disease

OBJECTIVES

To describe the diagnostic challenge associated with magnetic resonance imaging (MRI) artifact and to describe methods of minimizing this artifact.

METHODS

Gadolinium enhancement was demonstrated to be artifact by using an inversion recovery pulse sequence technique.

RESULTS

A patient with complaints of painless loss of vision also had radiologic abnormalities that led to subsequent referral to a tertiary care facility. Increased signals on the fat-suppressed contrast enhanced MRI was demonstrated to be artifact by using an inversion recovery technique which produced a normal MRI of the orbit.

CONCLUSIONS

Clinical confusion leading to unnecessary and costly evaluation may be avoided if one considers the possibility of artifact when reviewing magnetic resonance studies. When magnetic susceptibility is suspected, the use of an inversion recovery sequence can better delineate the true nature of the abnormality.

Neutron radii in nuclei and the neutron equation of state

The root-mean-square radius for neutrons in nuclei is investigated in the Skyrme Hartree-Fock model. The main source of theoretical variation comes from the exchange part of the density-dependent interaction which can be related to a basic property of the neutron equation of state. A precise measurement of the neutron radius in 208Pb would place an important new constraint on the equation of state for neutron matter. The Friedman-Pandharipande neutron equation of state would lead to a very precise value of 0.16+/-0.02 fm for the difference between the neutron and the proton root-mean-square radius in 208Pb.