168 research outputs found
TITAN's Digital RFQ Ion Beam Cooler and Buncher, Operation and Performance
We present a description of the Radio Frequency Quadrupole (RFQ) ion trap
built as part of the TITAN facility. It consists of a gas-filled, segmented,
linear Paul trap and is the first stage of the TITAN setup with the purpose of
cooling and bunching radioactive ion beams delivered from ISAC-TRIUMF. This is
the first such device to be driven digitally, i.e., using a high voltage
(), wide bandwidth ()
square-wave as compared to the typical sinusoidal wave form. Results from the
commissioning of the device as well as systematic studies with stable and
radioactive ions are presented including efficiency measurements with stable
Cs and radioactive Cs. A novel and unique mode of
operation of this device is also demonstrated where the cooled ion bunches are
extracted in reverse mode, i.e., in the same direction as previously injected.Comment: 34 pages, 17 figure
Highly charged ions in Penning traps, a new tool for resolving low lying isomeric states
The use of highly charged ions increases the precision and resolving power,
in particular for short-lived species produced at on-line radio-isotope beam
facilities, achievable with Penning trap mass spectrometers. This increase in
resolving power provides a new and unique access to resolving low-lying
long-lived ( ms) nuclear isomers. Recently, the keV
(determined from -ray spectroscopy) isomeric state in Rb has
been resolved from the ground state, in a charge state of with the TITAN
Penning trap at the TRIUMF-ISAC facility. The excitation energy of the isomer
was measured to be keV above the ground state. The extracted
masses for both the ground and isomeric states, and their difference, agree
with the AME2003 and Nuclear Data Sheet values. This proof of principle
measurement demonstrates the feasibility of using Penning trap mass
spectrometers coupled to charge breeders to study nuclear isomers and opens a
new route for isomer searches.Comment: 8 pages, 6 figure
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Inverse association between negative symptoms and body mass index in chronic schizophrenia.
BACKGROUND: We investigated whether negative symptoms, such as poor motivation or anhedonia, were associated with higher body mass index (BMI) in stable patients with schizophrenia chronically treated with antipsychotic medication. METHODS: 62 olanzapine- or clozapine-treated patients with illness duration of at least four years were selected from an international multicenter study on the characterization of negative symptoms. All participants completed the Brief Negative Symptom Scale (BNSS) and the Positive and Negative Syndrome Scale (PANSS). Bivariate correlations between BMI and negative symptoms (BNSS) were explored, as well as multiple regression analyses. We further explored the association of two principal component factors of the BNSS and BMI. Subsidiary analyses re-modeled the above using the negative symptoms subscale of the PANSS and the EMSLEY factor for negative symptoms for convergent validity. RESULTS: Lower negative symptoms (BNSS score) were associated with higher BMI (r=-0.31; p=0.015). A multiple regression analysis showed that negative symptoms (BNSS score) and age were significant predictors of BMI (p=0.037). This was mostly driven by the motivation/pleasure factor of the BNSS. Within this second factor, BMI was negatively associated with anhedonia (r=-0.254; p=0.046) and asociality (r=-0.253; p=0.048), but not avolition (r=-0.169; p=0.188). EMSLEY score was positively associated with BNSS (r=0.873, p<0.001), but negatively associated with BMI (r=-0.308; p=0.015). The association between PANSS and BMI did not reach significance (r=-224, p=0.080). CONCLUSIONS: We conclude that lower negative symptoms were associated with higher BMI (assessed using both the BNSS and EMSLEY) in chronic stable schizophrenia patients, mostly due to lower anhedonia and asociality levels
Tuberculosis diagnosis after bleach processing for early stage tuberculosis laboratory capacity building
The diagnosis of tuberculosis is seriously hampered in the absence of standard biosafety laboratory facilities for specimen concentration and Mycobacterium tuberculosis
culture. Within a laboratory twinning arrangement,heat-fixed direct smear and sediment from 74 bleach-processed and 20 non-processed specimens from Cumura Hospital, Guinea-Bissau, were sent to Lisbon for molecular evaluation of rifampicin resistance. Sequence analysis of a 369 base-pair rpoB locus detected 3.2% (3/94) resistant specimens. To our knowledge,
this represents the first report on the molecular analysis of M. tuberculosis from bleach-processed sputum, an alternative to current diagnostic practice in low-resource settings
Early onset of ground-state deformation in the neutron-deficient polonium isotopes
In-source resonant ionization laser spectroscopy of the even- polonium
isotopes Po has been performed using the
to ( nm) transition in the polonium atom
(Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope
shifts in Po with a previous data set allows to test for the first
time recent large-scale atomic calculations that are essential to extract the
changes in the mean-square charge radius of the atomic nucleus. When going to
lighter masses, a surprisingly large and early departure from sphericity is
observed, which is only partly reproduced by Beyond Mean Field calculations.Comment: As submitted to PR
Strong Decays of Strange Quarkonia
In this paper we evaluate strong decay amplitudes and partial widths of
strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give
numerical results for all energetically allowed open-flavor two-body decay
modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and
1F multiplets, comprising strong decays of a total of 43 resonances into 525
two-body modes, with 891 numerically evaluated amplitudes. This set of
resonances includes all strange qqbar states with allowed strong decays
expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic
quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical
results for all amplitudes present in each decay mode. We also discuss the
status of the associated experimental candidates, and note which states and
decay modes would be especially interesting for future experimental study at
hadronic, e+e- and photoproduction facilities. These results should also be
useful in distinguishing conventional quark model mesons from exotica such as
glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table
Exploration of cannabis use and polygenic risk scores on the psychotic symptom progression of a FEP cohort
Cannabis use is highly prevalent in first-episode psychosis (FEP) and plays a critical role in its onset and prognosis, but the genetic underpinnings promoting both conditions are poorly understood. Current treatment strategies for cannabis cessation in FEP are clearly inefficacious. Here, we aimed to characterize the association between cannabis-related polygenic risk scores (PRS) on cannabis use and clinical course after a FEP. A cohort of 249 FEP individuals were evaluated during 12 months. Symptom severity was measured with the Positive and Negative Severity Scale and cannabis use with the EuropASI scale. Individual PRS for lifetime cannabis initiation (PRSCI) and cannabis use disorder (PRSCUD) were constructed. Current cannabis use was associated with increased positive symptoms. Cannabis initiation at younger ages conditioned the 12-month symptom progression. FEP patients with higher cannabis PRSCUD reported increased baseline cannabis use. PRSCI was associated with the course of negative and general symptomatology over follow-up. Cannabis use and symptom progression after a FEP were modulated by cannabis PRS, suggesting that lifetime initiation and use disorders may have partially independent genetic factors. These exploratory results may be the first step to identify those FEP patients more vulnerable to cannabis use and worse outcomes to ultimately develop tailored treatments
Collaborative Training With a More Experienced Partner: Remediating Low Pretraining Self-Efficacy in Complex Skill Acquisition
Objective: This study examined the effectiveness of collaborative training for individuals with low pretraining self-efficacy versus individuals with high pretraining selfefficacy regarding the acquisition of a complex skill that involved strong cognitive and psychomotor demands. Background: Despite support for collaborative learning from the educational literature and the similarities between collaborative learning and interventions designed to remediate low self-efficacy, no research has addressed how selfefficacy and collaborative learning interact in contexts concerning complex skills and human-machine interactions. Method: One hundred fifty-five young male adults trained either individually or collaboratively with a more experienced partner on a complex computer task that simulated the demands of a dynamic aviation environment. Participants also completed a task-specific measure of self-efficacy before, during, and after training. Results: Collaborative training enhanced skill acquisition significantly more for individuals with low pretraining self-efficacy than for individuals with high pretraining self-efficacy. However, collaborative training did not bring the skill acquisition levels of those persons with low pretraining self-efficacy to the levels found for persons with high pretraining self-efficacy. Moreover, tests of mediation suggested that collaborative training may have enhanced appropriate skill development strategies without actually raising self-efficacy. Conclusion: Although collaborative training can facilitate the skill acquisition process for trainees with low self-efficacy, future research is needed that examines how the negative effects of low pretraining self-efficacy on complex skill acquisition can be more fully remediated. Application: The differential effects of collaborative training as a function of self-efficacy highlight the importance of person analysis and tailoring training to meet differing trainee needs.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
RpoB polymorphisms in Mycobacterium tuberculosis complex from a population in Guinea-Bissau
The global tuberculosis (TB) threat is diffi cult to evaluate in countries with scarce laboratory facilities where little is known about the genetic basis of drug resistance, including the rpoB RRDR (rifampicin
resistance determining region) of the Mycobacterium tuberculosis complex (MTC). The present study aimed at performing a preliminary evaluation of rpoB polymorphisms in a DNA set of MTC isolates from Guinea-Bissau patients.
Ninety-four sputum specimens (74 bleach processed and 20 unprocessed) were sent to Lisbon for molecular analysis (n=94) and drug susceptibility testing (n=20).
A 369bp region of the rpoB gene (including the 81bp RRDR), was amplifi ed. Sequencing was used as the gold standard for the identifi cation of point mutations.
Two polymorphisms were identifi ed: The alteration S531L, present in 3.2% of the specimens, and a new mutation, present in 28.7%, corresponding to nucleotide and amino acid polymorphism C224T and S469L, respectively, detected upstream from the RRDR, and not associated with RMP resistance.
An NCBI BLAST revealed M. tuberculosis K85
(M. africanum) as the only strain presenting this polymorphism.
The circulation of S531L mutated stains, associated with RMP resistance, points to the urgent need to further investigate RMP resistance in this African region. Moreover, the strains presenting the S469L polymorphism showed no other mutations suggesting that its role on MP´susceptibility/ resistance or in providing a genetic background for the occurrence of RMP resistance associated mutations should be further investigated. Also, future genotyping studies could clarify whether this new mutation is a genetic signature of some M. africanum strains
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