Uptake of groundwater nitrogen by a near-shore coral reef community on Bermuda

Nutrient enrichment can slow growth, enhance bioerosion rates, and intensify algal competition for reef-building corals. In areas of high human population density and/or limited waste management, submarine groundwater discharge can transfer anthropogenic nutrients from polluted groundwater to coastal reefs. In this case study, we investigate the impact of submarine groundwater discharge on a near-shore reef in Bermuda, where over 60% of sewage generated by the island’s 64,000 residents enters the groundwater through untreated cesspits. Temperature, salinity, pH, and alkalinity were monitored at a groundwater discharge vent, three locations across the adjacent coral reef (0–30 m from shore), and a comparison patch reef site 2 km from shore. Groundwater discharge was characterized by low salinity, low aragonite saturation state (Ω_(ar)), high alkalinity, elevated nitrate + nitrite (NO₃₋ + NO₂₋; hereafter, “NO₃₋”) concentrations (> 400 µM), and an elevated ¹⁵N/¹⁴N ratio of NO₃₋ (δ¹⁵N = 10.9 ± 0.02‰ vs. air, mean ± SD). Rainfall and tidal cycles strongly impacted groundwater discharge, with maximum discharge during low tide. NO₃₋ concentrations on the near-shore reef averaged 4 µM, ten times higher than that found at the control site 2 km away, and elevated NO₃₋ δ¹⁵N at the near-shore reef indicated sewage-contaminated groundwater as a significant nitrogen source. Tissue δ¹⁵N of Porites astreoides, a dominant reef-building coral, was elevated by ~ 3‰ on the near-shore reef compared to the control site, indicating that corals across the near-shore reef were assimilating groundwater-derived nitrogen. In addition, coral skeletal density and calcification rates across the near-shore reef were inversely correlated with NO₃₋ concentration and δ¹⁵N, indicating a negative coral health response to groundwater-borne nutrient inputs. P. astreoides bioerosion rates, in contrast, did not show an effect from the groundwater input

Pediatric pacemaker infections: Twenty years of experience

AbstractObjective: We sought to evaluate possible predictors of early and late pacemaker infections in children. Methods: A review was performed of all pacemakers implanted in children at The Children's Hospital of Philadelphia between 1982 and 2001. Infections were classified as superficial cellulitus, deep pacemaker pocket infection necessitating removal, or positive blood culture without an identifiable source. Results: A total of 385 pacemakers (224 epicardial and 161 endocardial) were implanted in 267 patients at 8.4 ± 6.2 years. All 2141 outpatient visits were reviewed (median follow-up, 29.4 months; range, 2-232 months). There were 30 (7.8%) pacemaker infections: 19 (4.9%) superficial infections; 9 (2.3%) pocket infections; and 2 (0.5%) isolated positive blood cultures. All superficial infections resolved with intravenous antibiotics. The median time from implantation to infection was 16 days (range, 2 days-5 years). Only 1 deep infection occurred after primary pacemaker implantation. Six patients with deep infections were pacemaker dependent and were successfully managed with intravenous antibiotics, followed by lead-generator removal and implantation of a new pacemaker in a remote location. In univariate analyses trisomy 21 (relative risk, 3.9; P <.01), pacemaker revisions (relative risk, 2.5; P <.01), and single-chamber devices (relative risk, 2.4; P <.05) were identified as predictors of infection. However, in multivariate analyses only trisomy 21 and pacemaker revisions were predictors. Conclusions: The incidences of superficial and deep pacemaker infections were 4.9% and 2.3%, respectively. Trisomy 21 and pacemaker revisions were significant risk factors in the development of infection after pacemaker implantation. For primary pacemaker implantation, the risk of infection requiring system removal is low (0.3%).J Thorac Cardiovasc Surg 2002;124:821-

The Use of Strontium-90 Beta Radiotherapy as Adjuvant Treatment for Conjunctival Melanoma

Background/Aims. To report the safety and efficacy of strontium (Sr90) beta radiotherapy as adjuvant treatment for conjunctival melanoma. Methods. A retrospective cohort study was undertaken from 1999 to 2007 of all patients who underwent Sr90 beta radiotherapy for incompletely excised conjunctival melanoma. Failure of treatment was defined as recurrence of a conjunctival melanoma at the same location following beta radiotherapy. Results. Twenty patients underwent Sr90 beta radiotherapy for incompletely excised conjunctival melanoma. Median follow-up interval was 59 months (8–152). All patients had conjunctival melanoma involving the bulbar conjunctiva. Underlying diagnoses included PAM with atypia in 60% (12 of 20), PAM without atypia in 15% (3 of 20), and de novo conjunctival melanoma in 25% (5 of 20). Following Sr90 beta radiotherapy, in 90% (18 out of 20) local control was achieved and visual acuity was not affected in any patient. Three patients (15%) had dry eye symptoms, episcleritis, and descemetcoele, respectively. No cataract or secondary glaucoma was reported. Conclusions. Sr90 treatment is a very effective adjuvant treatment after excisional biopsy and cryotherapy for conjunctival melanoma with a local success rate of 90%. The treatment is not associated with significant side effects and visual acuity is not affected

Anomaly Mediated Supersymmetry Breaking in Four Dimensions, Naturally

We present a simple four-dimensional model in which anomaly mediated supersymmetry breaking naturally dominates. The central ingredient is that the hidden sector is near a strongly-coupled infrared fixed-point for several decades of energy below the Planck scale. Strong renormalization effects then sequester the hidden sector from the visible sector. Supersymmetry is broken dynamically and requires no small input parameters. The model provides a natural and economical explanation of the hierarchy between the supersymmetry-breaking scale and the Planck scale, while allowing anomaly mediation to address the phenomenological challenges posed by weak scale supersymmetry. In particular, flavor-changing neutral currents are naturally near their experimental limits.Comment: 14 pages, Late

Fermion Masses in Emergent Electroweak Symmetry Breaking

We consider the generation of fermion masses in an emergent model of electroweak symmetry breaking with composite $W,Z$ gauge bosons. A universal bulk fermion profile in a warped extra dimension is used for all fermion flavors. Electroweak symmetry is broken at the UV (or Planck) scale where boundary mass terms are added to generate the fermion flavor structure. This leads to flavor-dependent nonuniversality in the gauge couplings. The effects are suppressed for the light fermion generations but are enhanced for the top quark where the $Zt{\bar t}$ and $Wt{\bar b}$ couplings can deviate at the $10-20$ level in the minimal setup. By the AdS/CFT correspondence our model implies that electroweak symmetry is not a fundamental gauge symmetry. Instead the Standard Model with massive fermions and $W,Z$ gauge bosons is an effective chiral Lagrangian for some underlying confining strong dynamics at the TeV scale, where mass is generated without a Higgs mechanism.Comment: modified discussion in Sec 3.1, version published in JHE

Natural forcing of the North Atlantic nitrogen cycle in the Anthropocene

Human alteration of the global nitrogen cycle intensified over the 1900s. Model simulations suggest that large swaths of the open ocean, including the North Atlantic and the western Pacific, have already been affected by anthropogenic nitrogen through atmospheric transport and deposition. Here we report an ∼130-year-long record of the ^(15)N/^(14)N of skeleton-bound organic matter in a coral from the outer reef of Bermuda, which provides a test of the hypothesis that anthropogenic atmospheric nitrogen has significantly augmented the nitrogen supply to the open North Atlantic surface ocean. The Bermuda ^(15)N/^(14)N record does not show a long-term decline in the Anthropocene of the amplitude predicted by model simulations or observed in a western Pacific coral ^(15)N/^(14)N record. Rather, the decadal variations in the Bermuda 15N/14N record appear to be driven by the North Atlantic Oscillation, most likely through changes in the formation rate of Subtropical Mode Water. Given that anthropogenic nitrogen emissions have been decreasing in North America since the 1990s, this study suggests that in the coming decades, the open North Atlantic will remain minimally affected by anthropogenic nitrogen deposition

Social, emotional, and behavioral functioning of secondary school students with low academic and language performance: perspectives from students, teachers, and parents

Adolescence is a time of transition when young people with language difficulties are at increased risk of experiencing social, emotional, and behavioral difficulties (SEBD). Most studies of social, emotional, and behavioral functioning (SEBF) in individuals with language difficulties focus on children with a clinical diagnosis of language impairment. This study explores SEBF in a nonclinical group of 12-year-old students with low educational and language performance from their own perspectives and those of their parents and teachers

Secluded Dark Matter Coupled to a Hidden CFT

Models of secluded dark matter offer a variant on the standard WIMP picture and can modify our expectations for hidden sector phenomenology and detection. In this work we extend a minimal model of secluded dark matter, comprised of a U(1)'-charged dark matter candidate, to include a confining hidden-sector CFT. This provides a technically natural explanation for the hierarchically small mediator-scale, with hidden-sector confinement generating m_{gamma'}>0. Furthermore, the thermal history of the universe can differ markedly from the WIMP picture due to (i) new annihilation channels, (ii) a (potentially) large number of hidden-sector degrees of freedom, and (iii) a hidden-sector phase transition at temperatures T << M_{dm} after freeze out. The mediator allows both the dark matter and the Standard Model to communicate with the CFT, thus modifying the low-energy phenomenology and cosmic-ray signals from the secluded sector.Comment: ~50p, 8 figs; v2 JHEP versio