The Fossil higher plants from the Canal Zone

Fossil flora described in the present report is too limited for purposes of exact correlation, which may be expected to be settled by the marine faunas present at most horizons in the Isthmian region. Accompanying table of distribution will show that from the oldest (Hohio) to the youngest (Gatun) plant-bearing formations there is no observable difference in floral facies. This so-called Oligocence series of formations does not represent any great interval of time. (39 page document

The Divergence of Human Capital Levels Across Cities

Over the past 30 years, the share of adult populations with college degrees increased more in cities with higher initial schooling levels than in initially less educated places. This tendency appears to be driven by shifts in labor demand as there is an increasing wage premium for skilled people working in skilled cities. In this paper, we present a model where the clustering of skilled people in metropolitan areas is driven by the tendency of skilled entrepreneurs to innovate in ways that employ other skilled people and by the elasticity of housing supply.

Information Processing In Anxiety And Depression: Attention Responses To Mood Congruent Stimuli

Previous research (e.g., MacLeod & Mathews, 1990) has found that anxious individuals show an attentional bias towards negative information, but evidence for such a bias in depressed individuals is equivocal. Conversely, there are fairly consistent findings that depressed individuals display a recall bias for negative information, whereas the findings for anxious individuals are mixed. However, task demands from this research may not have allowed anxious and depressed subjects to process information to the same extent. In the present study, 15 clinically depressed, 15 clinically anxious, 16 community control, 17 mildly depressed, 19 mildly anxious, and 17 nonclinical control subjects were tested on three attentional (modified dot probe, lexical decision, and negative priming) and two memory (word recall, and word completion) tasks using positive and negative words that were related to anxiety, depression, or a control condition. Clinically anxious and clinically depressed subjects both showed that some types of negative information (e.g., anxiety related) were more accessible than positive, but others were not (e.g., depression related, control). Also, clinically depressed subjects showed a tendency to disproportionately attend to negative information in general, whereas clinically anxious subjects avoided it. However, clinically depressed subjects were found to be slower to process information, and this effect could not be accounted for by motor retardation alone. It was concluded that clinically anxious and clinically depressed individuals recognize and respond to negative information in a similar fashion, except that clinically depressed individuals are slower in general to carry out these processes. The results from the two memory tasks indicated that clinically depressed subjects show a recall advantage for negative information. Clinically anxious subjects showed a similar, but less robust pattern. On all tasks, nonclinical samples showed similar, but less pervasive robust effects as their clinical counterparts. Overall, the results suggest that anxiety and depression are characterized by similar attentional biases, except that depressed individuals are slower processors. This difference may produce divergent patterns in later cognitive processes (e.g., memory) or their products

Assessing and supporting working memory in children: the role of attention and the environment

Working memory (WM) – the ability to store information over short periods of time in support of complex cognition – is implicated in a range of cognitive processes and developmental milestones. Given the importance of WM, it is vital that tools exist to rapidly but effectively assess this set of abilities. In Chapter 2 the development of computerised set of measures is described that we designed to facilitate rapid group testing in a school setting. These aims were defined by links with the Born in Bradford longitudinal cohort study. The rest of the thesis investigates how WM might be supported in children, a critical line of research considering the developmental implications of WM difficulties. In Chapter 3 the first investigation of the ability of children to prioritise serial positions within a visual sequence is presented. Children were instructed to try especially hard to remember either the first or third item in three-item sequences of shapes. Adults are consistently able to do this, resulting in superior performance for the prioritised item, at a cost to other items. Unlike adults, children did not show an ability to prioritise a particular position, when instructed to do so. Chapter 3 also includes a novel individual difference analysis that further clarifies the automaticity of recency effects in visual WM. Following the absence of prioritisation effects in Chapter 3, an alternative approach informed by embodied theories of cognition was taken in Chapter 4. Participants were presented with a WM task where the task environment was either structured pseudorandomly or in a task-relevant manner. This task-relevant organisation was consistently beneficial for children with low WM, such that they performed better than when the environment was structured. Children’s metacognitive understanding of the experimental manipulation was also investigated, highlighting the important of metacognitive factors to supporting WM in children

Cellular transduction mechanisms of adeno-associated viral vectors

Recombinant adeno-associated viral vectors (rAAV) are regarded as promising vehicles for therapeutic gene delivery. Continued development and new strategies are essential to improve the potency of AAV vectors and reduce the effective dose needed for clinical efficacy. In this regard, many studies have focused on understanding the cellular transduction mechanisms of rAAV, often with the goal of exploiting this knowledge to increase gene transfer efficiency. Here, we provide an overview of our evolving understanding of rAAV cellular trafficking pathways through the host cell, beginning with cellular entry and ending with transcription of the vector genome. Strategies to exploit this information for improving rAAV transduction are discussed

Analyses of space environment effects on active fiber optic links orbited aboard the LDEF

The results of the 'Preliminary Analysis of WL Experiment no. 701, Space Environment Effects on Operating Fiber Optic Systems,' is correlated with space simulated post retrieval terrestrial studies performed on the M0004 experiment. Temperature cycling measurements were performed on the active optical data links for the purpose of assessing link signal to noise ratio and bit error rate performance some 69 months following the experiment deployment in low Earth orbit. The early results indicate a high correlation between pre-orbit, orbit, and post-orbit functionality of the first known and longest space demonstration of operating fiber optic systems