110 research outputs found
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
Penning-trap mass spectrometry of highly charged, neutron-rich Rb and Sr isotopes in the vicinity of
The neutron-rich mass region around presents challenges for
modeling the astrophysical -process because of rapid shape transitions. We
report on mass measurements using the TITAN Penning trap at TRIUMF-ISAC to
attain more reliable theoretical predictions of -process nucleosynthesis
paths in this region. A new approach using highly charged () ions has
been applied which considerably saves measurement time and preserves accuracy.
New mass measurements of neutron-rich Rb and Sr have
uncertainties of less than 4 keV and show deviations of up to 11 to
previous measurements. An analysis using a parameterized -process model is
performed and shows that mass uncertainties for the A=90 abundance region are
eliminated
The Determination of alpha_s from Tau Decays Revisited
We revisit the determination of alpha_s(m_tau) using a fit to inclusive tau
hadronic spectral moments in light of (1) the recent calculation of the
fourth-order perturbative coefficient K_4 in the expansion of the Adler
function, (2) new precision measurements from BABAR of e+e- annihilation cross
sections, which decrease the uncertainty in the separation of vector and
axial-vector spectral functions, and (3) improved results from BABAR and Belle
on tau branching fractions involving kaons. We estimate that the fourth-order
perturbative prediction reduces the theoretical uncertainty, introduced by the
truncation of the series, by 20% with respect to earlier determinations. We
discuss to some detail the perturbative prediction and show that the effect of
the incomplete knowledge of the series is reduced by using the so-called
contour-improved calculation, as opposed to fixed-order perturbation theory
which manifests convergence problems. The corresponding theoretical
uncertainties are studied at the tau and Z mass scales. Nonperturbative
contributions extracted from the most inclusive fit are small, in agreement
with earlier determinations. Systematic effects from quark-hadron duality
violation are estimated with simple models and found to be within the quoted
systematic errors. The fit gives alpha_s(m_tau) = 0.344 +- 0.005 +- 0.007,
where the first error is experimental and the second theoretical. After
evolution to M_Z we obtain alpha_s(M_Z) = 0.1212 +- 0.0005 +- 0.0008 +- 0.0005,
where the errors are respectively experimental, theoretical and due to the
evolution. The result is in agreement with the corresponding NNNLO value
derived from essentially the Z width in the global electroweak fit. The
alpha_s(M_Z) determination from tau decays is the most precise one to date.Comment: 22 pages, 7 figure
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
Identifying clinical clusters with distinct trajectories in first-episode psychosis through an unsupervised machine learning technique
The extreme variability in symptom presentation reveals that individuals diagnosed with a first-episode psychosis (FEP) may encompass different sub-populations with potentially different illness courses and, hence, different treatment needs. Previous studies have shown that sociodemographic and family environment factors are associated with more unfavorable symptom trajectories. The aim of this study was to examine the dimensional structure of symptoms and to identify individuals’ trajectories at early stage of illness and potential risk factors associated with poor outcomes at follow-up in non-affective FEP. One hundred and forty-four non-affective FEP patients were assessed at baseline and at 2-year follow-up. A Principal component analysis has been conducted to identify dimensions, then an unsupervised machine learning technique (fuzzy clustering) was performed to identify clinical subgroups of patients. Six symptom factors were extracted (positive, negative, depressive, anxiety, disorganization and somatic/cognitive). Three distinct clinical clusters were determined at baseline: mild; negative and moderate; and positive and severe symptoms, and five at follow-up: minimal; mild; moderate; negative and depressive; and severe symptoms. Receiving a low-dose antipsychotic, having a more severe depressive symptomatology and a positive family history for psychiatric disorders were risk factors for poor recovery, whilst having a high cognitive reserve and better premorbid adjustment may confer a better prognosis. The current study provided a better understanding of the heterogeneous profile of FEP. Early identification of patients who could likely present poor outcomes may be an initial step for the development of targeted interventions to improve illness trajectories and preserve psychosocial functioning
The role of premorbid iq and age of onset as useful predictors of clinical, functional outcomes, and recovery of individuals with a first episode of psychosis
Background: premorbid IQ (pIQ) and age of onset are predictors of clinical severity and long-term functioning after a first episode of psychosis. However, the additive influence of these variables on clinical, functional, and recovery rates outcomes is largely unknown. Methods: we characterized 255 individuals who have experienced a first episode of psychosis in four a priori defined subgroups based on pIQ (low pIQ < 85; average pIQ = 85) and age of onset (early onset < 18 years; adult onset = 18 years). We conducted clinical and functional assessments at baseline and at two-year follow-up. We calculated symptom remission and recovery rates using the Positive and Negative Symptoms of Schizophrenia Schedule (PANSS) and the Global Assessment Functioning (GAF or Children-GAF). We examined clinical and functional changes with pair-wise comparisons and two-way mixed ANOVA. We built hierarchical lineal and logistic regression models to estimate the predictive value of the independent variables over functioning or recovery rates. Results: early-onset patients had more severe positive symptoms and poorer functioning than adult-onset pa-tients. At two-year follow-up, only early-onset with low pIQ and adult-onset with average pIQ subgroups differed consistently, with the former having more negative symptoms (d = 0.59), poorer functioning (d = 0.82), lower remission (61% vs. 81.1%), and clinical recovery (34.1% vs. 62.2%). Con-clusions: early-onset individuals with low pIQ may present persistent negative symptoms, lower functioning, and less recovery likelihood at two-year follow-up. Intensive cognitive and functional programs for these individuals merit testing to improve long-term recovery rates in this subgroup. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Nuclear Spins and Magnetic Moments of 71,73,75Cu: Inversion of π2p3/2 and π1f5/2 Levels in 75Cu
Predictors of nurses’ and midwives’ intentions to provide maternal and child healthcare services to adolescents in South Africa
BACKGROUND: Adolescent mothers are at a much higher risk for maternal mortality compared to mothers aged
20 years and above. Newborns born to adolescent mothers are also more likely to have low birth weight, with the
risk of long-term effects such as early onset of adult diabetes than newborns of older mothers. Few studies have
investigated the determinants of adequate quality maternal and child healthcare services to pregnant adolescents.
This study was conducted to gain an understanding of nurses’ and midwives’ intentions to provide maternal and
child healthcare and family planning services to adolescents in South Africa.
METHODS: A total of 190 nurses and midwives completed a cross-sectional survey. The survey included components
on demographics, knowledge of maternal and child healthcare (MCH) and family planning (FP) services, attitude
towards family planning services, subjective norms regarding maternal and child healthcare and family planning
services, self-efficacy with maternal and child healthcare and family planning services, and intentions to provide
maternal and child healthcare and family planning services to adolescents. Pearson’s correlation analysis was
conducted to determine the association between knowledge, attitude, subjective norms, self-efficacy, and intention
variables for FP and MCH services. A 2-step linear regression analysis was then conducted for both FP and MCH
services to predict the intentions to provide FP and MCH services to adolescents.
RESULTS: Self-efficacy to conduct MCH services (β = 0.55, p < 0.01) and years of experience as a nurse- midwife
(β = 0.14, p < 0.05) were associated with stronger intentions to provide the services. Self-efficacy to provide FP
services (β = 0.30, p < 0.01) was associated with stronger intentions to provide FP services.
CONCLUSIONS: Self-efficacy has a strong and positive association with the intentions to provide both MCH and FP
services, while there is a moderate association with attitude and norms. There is a need to improve and strengthen
nurses’ and midwives’ self-efficacy in conducting both MCH and FP services in order to improve the quality and
utilization of the services by adolescents in South Africa.IS
Experimental Study of the Reaction in the Energy Range GeV
We present a measurement of the cross section in the
energy range GeV. For the energy
GeV the cross section exceeds vector meson dominance model predictions with
only , , and mesons taken into account.
Measured cross section agrees well with previous measurements.Comment: 15 pages, 5 figure
Predicting Individuals' Learning Success from Patterns of Pre-Learning MRI Activity
Performance in most complex cognitive and psychomotor tasks improves with training, yet the extent of improvement varies among individuals. Is it possible to forecast the benefit that a person might reap from training? Several behavioral measures have been used to predict individual differences in task improvement, but their predictive power is limited. Here we show that individual differences in patterns of time-averaged T2*-weighted MRI images in the dorsal striatum recorded at the initial stage of training predict subsequent learning success in a complex video game with high accuracy. These predictions explained more than half of the variance in learning success among individuals, suggesting that individual differences in neuroanatomy or persistent physiology predict whether and to what extent people will benefit from training in a complex task. Surprisingly, predictions from white matter were highly accurate, while voxels in the gray matter of the dorsal striatum did not contain any information about future training success. Prediction accuracy was higher in the anterior than the posterior half of the dorsal striatum. The link between trainability and the time-averaged T2*-weighted signal in the dorsal striatum reaffirms the role of this part of the basal ganglia in learning and executive functions, such as task-switching and task coordination processes. The ability to predict who will benefit from training by using neuroimaging data collected in the early training phase may have far-reaching implications for the assessment of candidates for specific training programs as well as the study of populations that show deficiencies in learning new skills
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