Iron Deficiency Increases Growth and Nitrogen-Fixation Rates of Phosphorus-Deficient Marine Cyanobacteria

Marine dinitrogen (N2)-fixing cyanobacteria have large impacts on global biogeochemistry as they fix carbon dioxide (CO2) and fertilize oligotrophic ocean waters with new nitrogen. Iron (Fe) and phosphorus (P) are the two most important limiting nutrients for marine biological N2 fixation, and their availabilities vary between major ocean basins and regions. A long-standing question concerns the ability of two globally dominant N2-fixing cyanobacteria, unicellular Crocosphaera and filamentous Trichodesmium, to maintain relatively high N2-fixation rates in these regimes where both Fe and P are typically scarce. We show that under P-deficient conditions, cultures of these two cyanobacteria are able to grow and fix N2 faster when Fe deficient than when Fe replete. In addition, growth affinities relative to P increase while minimum concentrations of P that support growth decrease at low Fe concentrations. In Crocosphaera, this effect is accompanied by a reduction in cell sizes and elemental quotas. Relatively high growth rates of these two biogeochemically critical cyanobacteria in low-P, low-Fe environments such as those that characterize much of the oligotrophic ocean challenge the common assumption that low Fe levels can have only negative effects on marine primary producers. The closely interdependent influence of Fe and P on N2-fixing cyanobacteria suggests that even subtle shifts in their supply ratio in the past, present and future oceans could have large consequences for global carbon and nitrogen cycles

Whitebark Pine Stand Condition, Tree Abundance, and Cone Production as Predictors of Visitation by Clark's Nutcracker

Accurately quantifying key interactions between species is important for developing effective recovery strategies for threatened and endangered species. Whitebark pine (Pinus albicaulis), a candidate species for listing under the Endangered Species Act, depends on Clark's nutcracker (Nucifraga columbiana) for seed dispersal. As whitebark pine succumbs to exotic disease and mountain pine beetles (Dendroctonus ponderosae), cone production declines, and nutcrackers visit stands less frequently, reducing the probability of seed dispersal.We quantified whitebark pine forest structure, health metrics, and the frequency of nutcracker occurrence in national parks within the Northern and Central Rocky Mountains in 2008 and 2009. Forest health characteristics varied between the two regions, with the northern region in overall poorer health. Using these data, we show that a previously published model consistently under-predicts the proportion of survey hours resulting in nutcracker observations at all cone density levels. We present a new statistical model of the relationship between whitebark pine cone production and the probability of Clark's nutcracker occurrence based on combining data from this study and the previous study.Our model clarified earlier findings and suggested a lower cone production threshold value for predicting likely visitation by nutcrackers: Although nutcrackers do visit whitebark pine stands with few cones, the probability of visitation increases with increased cone production. We use information theoretics to show that beta regression is a more appropriate statistical framework for modeling the relationship between cone density and proportion of survey time resulting in nutcracker observations. We illustrate how resource managers may apply this model in the process of prioritizing areas for whitebark pine restoration

Evaluation of gait symmetry in poliomyelitis subjects : Comparison of a conventional knee ankle foot orthosis (KAFO) and a new powered KAFO.

Background: Compared to able-bodied subjects, subjects with post polio syndrome and poliomyelitis demonstrate a preference for weight-bearing on the non-paretic limb, causing gait asymmetry. Objectives: The purpose of this study was to evaluate the gait symmetry of the poliomyelitis subjects when ambulating with either a drop- locked knee ankle foot orthosis (KAFO) or a newly developed powered KAFO. Methods: Seven subjects with poliomyelitis who routinely wore conventional KAFOs participated in this study, and received training to enable them to ambulate with the powered KAFO on level ground, prior to gait analysis. Results: There were no significant differences in the gait symmetry index (SI) of step length (P=0.085), stance time (P=0.082), double limb support time (P=0.929) or speed of walking (p=0.325) between the two test conditions. However, using the new powered KAFO improved the SI in step width (P=0.037), swing time (P=0.014), stance phase percentage (P=0.008) and knee flexion during swing phase (p≤0.001) compared to wearing the dropped locked KAFO. Conclusion: The use of a powered KAFO for ambulation by poliomyelitis subjects affects gait symmetry in the base of support, swing time, stance phase percentage and knee flexion during swing phase

Underrepresentation of Elderly People in Randomised Controlled Trials. The Example of Trials of 4 Widely Prescribed Drugs

BACKGROUND: We aimed to determine the representation of elderly people in published reports of randomized controlled trials (RCTs). We focused on trials of 4 medications--pioglitazone, rosuvastatin, risedronate, and valsartan-frequently used by elderly patients with chronic medical conditions. METHODS AND FINDINGS: We selected all reports of RCTs indexed in PubMed from 1966 to April 2008 evaluating one of the 4 medications of interest. Estimates of the community-based "on-treatment" population were from a national health insurance database (SNIIR-AM) covering approximately 86% of the population in France. From this database, we evaluated data claims from January 2006 to December 2007 for 1,958,716 patients who received one of the medications of interest for more than 6 months. Of the 155 RCT reports selected, only 3 studies were exclusively of elderly patients (2 assessing valsartan; 1 risedronate). In only 4 of 37 reports (10.8%) for pioglitazone, 4 of 22 (18.2%) for risedronate, 3 of 29 (10.3%) for rosuvastatine and 9 of 67 (13.4%) for valsartan, the proportion of patients aged 65 or older was within or above that treated in clinical practice. In 62.2% of the reports for pioglitazone, 40.9% for risedronate, 37.9% for rosuvastatine, and 70.2% for valsartan, the proportion of patients aged 65 or older was lower than half that in the treated population. The representation of elderly people did not differ by publication date or sample size. CONCLUSIONS: Elderly patients are poorly represented in RCTs of drugs they are likely to receive

Health burden and economic impact of measles-related hospitalizations in Italy in 2002–2003

Background: A large measles outbreak occurred in Italy in 2002 - 2003. This study evaluates the health burden and economic impact of measles- related hospitalizations in Italy during the specified period. Methods: Hospital discharge abstract data for measles hospitalizations in Italy during 2002 - 2003 were analysed to obtain information regarding number and rates of measles hospitalizations by geographical area and age group, length of hospital stay, and complications. Hospitalization costs were estimated on the basis of Diagnosis- Related Groups. Results: A total of 5,154 hospitalizations were identified, 3,478 ( 67%) of which occurred in children < 15 years of age. Most hospitalizations occurred in southern Italy ( 71 %) and children below 1 year of age presented the greatest hospitalization rates ( 46.2/ 100,000 and 19.0/ 100,000, respectively in 2002 and 2003). Pneumonia was diagnosed in 594 cases ( 11.5%) and encephalitis in 138 cases ( 2.7%). Total hospital charges were approximately (sic) 8.8 million. Conclusion: The nationwide health burden associated with measles during the 2002 - 2003 outbreak was substantial and a high cost was incurred by the Italian National Health Service for the thousands of measles- related hospitalizations which occurred. By assuming that hospital costs represent 40 - 50% of the direct costs of measles cases, direct costs of measles for the two years combined were estimated to be between (sic)17.6 - 22.0 million, which equates to the vaccination of 1.5 - 1.9 million children ( 3 - 4 birth cohorts) with one dose of MMR. The high cost of measles and the severity of its complications fully justify the commitment required to reach measles elimination

Evidence for Shared Cognitive Processing of Pitch in Music and Language

Language and music epitomize the complex representational and computational capacities of the human mind. Strikingly similar in their structural and expressive features, a longstanding question is whether the perceptual and cognitive mechanisms underlying these abilities are shared or distinct – either from each other or from other mental processes. One prominent feature shared between language and music is signal encoding using pitch, conveying pragmatics and semantics in language and melody in music. We investigated how pitch processing is shared between language and music by measuring consistency in individual differences in pitch perception across language, music, and three control conditions intended to assess basic sensory and domain-general cognitive processes. Individuals’ pitch perception abilities in language and music were most strongly related, even after accounting for performance in all control conditions. These results provide behavioral evidence, based on patterns of individual differences, that is consistent with the hypothesis that cognitive mechanisms for pitch processing may be shared between language and music.National Science Foundation (U.S.). Graduate Research Fellowship ProgramEunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.) (Grant 5K99HD057522

Knowledge systems, health care teams, and clinical practice: a study of successful change

Clinical teams are of growing importance to healthcare delivery, but little is known about how teams learn and change their clinical practice. We examined how teams in three US hospitals succeeded in making significant practice improvements in the area of antimicrobial resistance. This was a qualitative cross-case study employing Soft Knowledge Systems as a conceptual framework. The purpose was to describe how teams produced, obtained, and used knowledge and information to bring about successful change. A purposeful sampling strategy was used to maximize variation between cases. Data were collected through interviews, archival document review, and direct observation. Individual case data were analyzed through a two-phase coding process followed by the cross-case analysis. Project teams varied in size and were multidisciplinary. Each project had more than one champion, only some of whom were physicians. Team members obtained relevant knowledge and information from multiple sources including the scientific literature, experts, external organizations, and their own experience. The success of these projects hinged on the teams' ability to blend scientific evidence, practical knowledge, and clinical data. Practice change was a longitudinal, iterative learning process during which teams continued to acquire, produce, and synthesize relevant knowledge and information and test different strategies until they found a workable solution to their problem. This study adds to our understanding of how teams learn and change, showing that innovation can take the form of an iterative, ongoing process in which bits of K&I are assembled from multiple sources into potential solutions that are then tested. It suggests that existing approaches to assessing the impact of continuing education activities may overlook significant contributions and more attention should be given to the role that practical knowledge plays in the change process in addition to scientific knowledge

A Model of Collective Interpretation

We propose a cognitively plausible formal model of collective interpretation. The model represents how members of a collective interact to interpret their environment. Current theories of collective interpretation focus on how heedful communication among members of a collective (i.e., how much individuals pay attention to others' interpretations) improves interpretive performance; their general assumption is that heed tends to be uniformly beneficial. By unpacking the micromechanisms that underlie such performance, our model reveals a more complex story. Heedfulness can benefit interpretive performance. It can help collectives properly interpret situations that are especially ambiguous, unknown, or novel. Conversely, heedfulness also generates conformity pressures that induce agents to give too much weight to others' interpretations, even if erroneous, thereby potentially degrading interpretive performance. These two effects join into a nonmonotonic trajectory that represents how heed relates to interpretive performance: due to its beneficial properties, performance increases with heed until it peaks before degrading due to conformity pressures. The form of this nonmonotonic relationship is contingent on the nature of the task: ambiguous situations make collectives vulnerable to too much heed: ambiguity ignites conformism; novel situations make collectives dependent on heed: novelty requires multiple eyes to be seen. In addition to these results, our model offers a flexible platform that future work can use to explore collective interpretation in a variety of organizational and supraorganizational contexts.We propose a cognitively plausible formal model of collective interpretation. The model represents how members of a collective interact to interpret their environment. Current theories of collective interpretation focus on how heedful communication among members of a collective (i.e., how much individuals pay attention to others' interpretations) improves interpretive performance; their general assumption is that heed tends to be uniformly beneficial. By unpacking the micromechanisms that underlie such performance, our model reveals a more complex story. Heedfulness can benefit interpretive performance. It can help collectives properly interpret situations that are especially ambiguous, unknown, or novel. Conversely, heedfulness also generates conformity pressures that induce agents to give too much weight to others' interpretations, even if erroneous, thereby potentially degrading interpretive performance. These two effects join into a nonmonotonic trajectory that represents how heed relates to interpretive performance: due to its beneficial properties, performance increases with heed until it peaks before degrading due to conformity pressures. The form of this nonmonotonic relationship is contingent on the nature of the task: ambiguous situations make collectives vulnerable to too much heed: ambiguity ignites conformism; novel situations make collectives dependent on heed: novelty requires multiple eyes to be seen. In addition to these results, our model offers a flexible platform that future work can use to explore collective interpretation in a variety of organizational and supraorganizational contexts