2,645 research outputs found
Causal Effects of Paternity Leave on Children and Parents
In this paper we use a parental leave reform directed towards fathers to identify the causal effects of paternity leave on children’s and parents’ outcomes. We document that paternity leave causes fathers to become more important for children’s cognitive skills. School performance at age 16 increases for children whose father is relatively higher educated than the mother. We find no evidence that fathers’ earnings and work hours are affected by paternity leave. Contrary to expectation, mothers’ labor market outcomes are adversely affected by paternity leave. Our findings do therefore not suggest that paternity leave shifts the gender balance at home in a way that increases mothers’ time and/or effort spent at market work.parental leave, labor supply, child development
A multi-level preconditioned Krylov method for the efficient solution of algebraic tomographic reconstruction problems
Classical iterative methods for tomographic reconstruction include the class
of Algebraic Reconstruction Techniques (ART). Convergence of these stationary
linear iterative methods is however notably slow. In this paper we propose the
use of Krylov solvers for tomographic linear inversion problems. These advanced
iterative methods feature fast convergence at the expense of a higher
computational cost per iteration, causing them to be generally uncompetitive
without the inclusion of a suitable preconditioner. Combining elements from
standard multigrid (MG) solvers and the theory of wavelets, a novel
wavelet-based multi-level (WMG) preconditioner is introduced, which is shown to
significantly speed-up Krylov convergence. The performance of the
WMG-preconditioned Krylov method is analyzed through a spectral analysis, and
the approach is compared to existing methods like the classical Simultaneous
Iterative Reconstruction Technique (SIRT) and unpreconditioned Krylov methods
on a 2D tomographic benchmark problem. Numerical experiments are promising,
showing the method to be competitive with the classical Algebraic
Reconstruction Techniques in terms of convergence speed and overall performance
(CPU time) as well as precision of the reconstruction.Comment: Journal of Computational and Applied Mathematics (2014), 26 pages, 13
figures, 3 table
High prevalence of curable sexually transmitted infections among pregnant women in a rural county hospital in Kilifi, Kenya
Background : Women attending antenatal care (ANC) in resource-limited countries are frequently screened for syphilis and HIV, but rarely for other sexually transmitted infections (STIs). We assessed the prevalence of curable STIs, defined as infection with either Chlamydia trachomatis or Neisseria gonorrhoeae or Trichomonas vaginalis, from July to September 2015.
Methods : In a cross-sectional study, women attending ANC at the Kilifi County Hospital, Kenya, had a urine sample tested for C. trachomatis/N. gonorrhoeae by GeneXpert and a vaginal swab for T. vaginalis by culture. Bacterial vaginosis (BV) was defined as a Nugent score of 7-10 of the Gram stain of a vaginal smear in combination with self-reported vaginal discharge. Genital ulcers were observed during collection of vaginal swabs. All women responded to questions on socio-demographics and sexual health and clinical symptoms of STIs. Predictors for curable STIs were assessed in multivariable logistic regression.
Results : A total of 42/202 (20.8%, 95% confidence interval (CI):15.4-27.0) women had a curable STI. The prevalence was 14.9% for C. trachomatis (95% Cl:10.2-20.5), 1.0% for N. gonorrhoeae (95% CI: 0.1-3.5), 7.4% for T. vaginalis (95% CI:4.2-12.0), 19.3% for BV (95% CI: 14.1-25.4) and 2.5% for genital ulcers (95% CI: 0.8-5.7). Predictors for infection with curable STIs included women with a genital ulcer (adjusted odds ratio (AOR) = 35.0, 95% CI: 2.7-461.6) compared to women without a genital ulcer, women who used water for cleaning after visiting the toilet compared to those who used toilet paper or other solid means (AOR = 4.1, 95% CI:1.5-11.3), women who reported having sexual debut = 18 years (AOR = 2.7, 95% Cl:1.1-6.6), and BV-positive women (AOR = 2.7, 95% Cl:1.1-6.6) compared to BV-negative women.
Conclusion : One in five women attending ANC had a curable STI. These infections were associated with genital ulcers, hygiene practices, early sexual debut and bacterial vaginosis
Constraints on the evolution of azole resistance in plant pathogenic fungi
The durability of azole fungicides in controlling agriculturally important pathogenic fungi is unique amongst modern single site fungicides. Today, azoles are still relied on to control pathogens of many crops including cereals, fruits and vegetables, canola and soybeans. Significantly, this widespread use continues despite many reports of azole-resistant fungal strains. In this review, recent reports of azole resistance and the mechanisms associated with resistant phenotypes are discussed. The example of the complex evolution of the azole target sterol 14-demethylase (CYP51) enzyme in modern European populations of the wheat pathogen Mycosphaerella graminicola is used to describe the quantitative and epistatic effects on fungicide sensitivity and enzyme function of target site mutations, and to explore the hypothesis that constraints on CYP51 evolution have ensured the longevity of azoles. In addition, the threats posed by alternative resistance mechanisms causing cross-resistance to all azoles or even unrelated fungicides are discussed, and postulations are made on how using new genomic technologies to gain a greater understanding of azole resistance evolution should enhance the ability to control azole-resistant strains of plant pathogenic fungi in the future
Onion gene expression in response to ethylene and 1-MCP
Onion is regarded as a non-climacteric vegetable. In onions, however,
ethylene can suppress sprouting while the ethylene binding inhibitor, 1-MCP (1-
methylcyclopropene) can also suppress sprout growth yet, it is unknown how ethylene
and 1-MCP elicit the same response. In this study, onions were treated with 10 ÎĽL L-1
ethylene or 1 μL L-1 1-MCP individually or in combination for 24 h at 20°C before or
after curing (six weeks) at 20 or 28°C then stored at 1°C. Following curing, a subset
of these same onions was stored separately under continuous air or ethylene (10 ÎĽL L-
1) at 1°C
Onions treated with ethylene and 1-MCP in combination after curing for 24 h
had reduced sprout growth as compared with the control 25 weeks after harvest.
Sprout growth following storage beyond 25 weeks was only reduced through
continuous ethylene treatment. This observation was supported by a higher proportion
of down-regulated genes characterised as being involved in photosynthesis measured
using a newly developed onion microarray. Physiological and biochemical data
suggested that ethylene was being perceived in the presence of 1-MCP since sprout
growth was reduced in onions treated with 1-MCP and ethylene applied in
combination but not when applied individually. A cluster of probes representing
transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or in
the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down52
regulated a probe tentatively annotated as an ethylene receptor as well as EIN3,
suggesting that both treatments down-regulate the perception and signalling events of
ethylene
On the Hierarchical Preconditioning of the PMCHWT Integral Equation on Simply and Multiply Connected Geometries
We present a hierarchical basis preconditioning strategy for the
Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) integral equation considering
both simply and multiply connected geometries.To this end, we first consider
the direct application of hierarchical basis preconditioners, developed for the
Electric Field Integral Equation (EFIE), to the PMCHWT. It is notably found
that, whereas for the EFIE a diagonal preconditioner can be used for obtaining
the hierarchical basis scaling factors, this strategy is catastrophic in the
case of the PMCHWT since it leads to a severly ill-conditioned PMCHWT system in
the case of multiply connected geometries. We then proceed to a theoretical
analysis of the effect of hierarchical bases on the PMCHWT operator for which
we obtain the correct scaling factors and a provably effective preconditioner
for both low frequencies and mesh refinements. Numerical results will
corroborate the theory and show the effectiveness of our approach
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