Silicic acid limitation drives bloom termination and potential carbon sequestration in an Arctic bloom.

The spring diatom bloom in the Arctic Ocean accounts for significant annual primary production leading to the most rapid annual drawdown of water-column pCO2. Late-winter waters in the Atlantic Arctic & Subarctic Provinces (AASP) have lower silicic acid concentrations than nitrate, which suggests diatom blooms may deplete Si before N. Here we test a facet of the hypothesis that silicic acid limitation terminates the spring diatom bloom in the AASP and the sinking of the senescent and dead diatoms helps drive carbon sequestration. During a 6-week study, diatoms bloomed and progressively consumed silicic acid to where it limited their growth. The onset of growth limitation was concurrent with the minimum pCO2 in the surface waters and increases in both the proportion of dead diatoms and the diatom assemblage sedimentation rate. Data reanalysis within the AASP shows a highly significant and positive correlation between silicic acid and pCO2 in the surface waters, but no significant relationship with nitrate and pCO2 was observed unless data were smoothed. Therefore, understanding the future of the AASP spring diatom bloom requires models that explicitly consider changes in silicic acid supply as a driver of this process.

Living with fair use and TEACH: a quest for compliance.

With the expansion of Web-based courses in nursing education, faculty members are faced with a greater responsibility to be copyright compliant. This article reviews the changes in copyright law. The Conference on Fair Use (CONFU), the passage of the Digital Millennium and Copyright Act (DMCA), the passage of the Technology Education and Copyright Harmonization (TEACH) Act, and recent legal cases will be discussed. The strategies and resources the authors used to secure copyright permission while designing a Web-based continuing education course will also be described.

The negative impact of the repeal of the Arkansas motorcycle helmet law.

BACKGROUND: On July 1, 1997, Arkansas became the first state in 14 years to repeal their adult helmet law. We examined the clinical and financial impact of this repeal. METHODS: A 6-year retrospective review was conducted of the University of Arkansas for Medical Sciences trauma registry including the 3 years before and the 3 years after the repeal of the helmet law. A head and neck Abbreviated Injury Scale (AIS) score >or= 3 was considered severe. All patients admitted to the hospital or who died in the emergency department were included in the study. The database of the Arkansas Highway and Transportation Department was also used to determine the number of crashes and fatalities occurring statewide (1995-1999). RESULTS: Although total and fatal crashes in Arkansas were not significantly different (1995-1996 vs. 1998-1999), nonhelmeted deaths at the scene of a crash significantly increased from 19 of 48 (39.6%) (1995-1996) to 40 of 53 (75.5%) (1998-1999) (p < 0.0001). Before repeal, 25% of nonfatal crash admissions were nonhelmeted (18 of 73). This significantly increased to 54% (52 of 96, p< 0.001) after repeal. Overall, patients who were nonhelmeted had significantly higher AIS scores for head and neck, significantly more severe head injuries (AIS score >or= 3), 47% (33 of 70) versus 20% (20 of 99), and significantly longer length of intensive care unit stay. Financially, patients without helmets had significantly higher unreimbursed charges compared with their helmeted counterparts, resulting in a total of 982,560 dollars of additional potentially lost revenue over the length of the study. CONCLUSION: Repeal of the mandatory helmet law was associated with an increase in the nonhelmeted crash scene fatality rate. After the repeal, there was a disproportionately higher admission rate for nonhelmeted motorcycle crash survivors. These patients had an increased use of hospital resources and poorer reimbursement of charges compared with their helmeted counterparts. This resulted in significantly higher unreimbursed charges. States considering repeal of their mandatory adult helmet laws should consider the potential negative financial impact on their health care system and the increased morbidity associated with nonhelmeted motorcycle riders involved in a crash.