Empirical Evidence on Growth and Volatility

This paper empirically investigates the relationship between long-run economic growth and output volatility. There is an emerging theoretical literature on the topic which is inconclusive on the size and direction of the relationship. We analyze this relationship empirically for the time series experience of 21 OECD countries between the years 1961 and 2005. After applying a pooled OLS estimator and a series of robustness checks we conclude that there is strong empirical evidence for a positive relationship between output variability and economic growth.Growth, Volatility, Cycles, Innovation

Neither a Multi-Ingredient Pre-Workout Supplement nor Caffeine Were Effective at Improving Markers of Blood Flow or Upper-Body Resistance Exercise Performance

International Journal of Exercise Science 13(2): 167-182, 2020. Few studies have measured the effects of multi-ingredient pre-workout supplements on blood flow or heart rate variability or have compared a multi-ingredient pre-workout supplement to a matched single ingredient. This study examined the effects of a multi-ingredient pre-workout supplement, an equivalent amount of caffeine, and placebo on markers of resistance training performance, blood flow, blood pressure, and heart rate variability. The study utilized a randomized, placebo-controlled, repeated-measures, crossover design. Twelve resistance-trained males (22.75 ± 4.51 yrs; 183.4 ± 7.37 cm; 91.05 ± 17.77 kg) completed the study. Resistance exercise performance was defined as total work performed during elbow flexion and extension on an isokinetic dynamometer. Blood flow was calculated using time-averaged mean velocity and blood vessel diameter of the right brachial artery, which were measured via Doppler ultrasound. Heart rate was recorded using an electrocardiogram. Neither a multi-ingredient pre-workout supplement nor caffeine alone improved upper-body resistance exercise performance or markers of blood flow relative to placebo. No differences in heart rate variability were observed across treatments. A multi-ingredient pre-workout supplement was not effective at improving performance or blood flow and did not alter autonomic nervous system function

Cytotoxic T Lymphocyte Trafficking and Survival in an Augmented Fibrin Matrix Carrier

Cell-based therapies have intriguing potential for the treatment of a variety of neurological disorders. One such example is genetically engineered cytotoxic T lymphocytes (CTLs) that are being investigated in brain tumor clinical trials. The development of methods for CTL delivery is critical to their use in the laboratory and clinical setting. In our study, we determined whether CTLs can migrate through fibrin matrices and if their migration, survival, and function could be modulated by adding chemokines to the matrix. Our results indicated that CTLs can freely migrate through fibrin matrices. As expected, the addition of the monocyte chemotactic protein-1 (MCP-1), also known as chemokine C-C motif ligand 2 (CCL2), to the surrounding media increased egress of the CTLs out of the fibrin clot. Interleukin (IL) -2 and/or IL-15 embedded in the matrix enhanced T cell survival and further promoted T cell migration. The interleukin-13 receptor alpha 2 specific (IL-13R alpha2) T cells that traveled out of the fibrin clot retained the capacity to kill U251 glioma cells. In summary, CTLs can survive and migrate robustly in fibrin matrices. These processes can be influenced by modification of matrix constituents. We conclude that fibrin matrices may be suitable T cell carriers and can be used to facilitate understanding of T cell interaction with the surrounding microenvironment

A Large-Scale Rheumatoid Arthritis Genetic Study Identifies Association at Chromosome 9q33.2

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease affecting both joints and extra-articular tissues. Although some genetic risk factors for RA are well-established, most notably HLA-DRB1 and PTPN22, these markers do not fully account for the observed heritability. To identify additional susceptibility loci, we carried out a multi-tiered, case-control association study, genotyping 25,966 putative functional SNPs in 475 white North American RA patients and 475 matched controls. Significant markers were genotyped in two additional, independent, white case-control sample sets (661 cases/1322 controls from North America and 596 cases/705 controls from The Netherlands) identifying a SNP, rs1953126, on chromosome 9q33.2 that was significantly associated with RA (ORcommon = 1.28, trend Pcomb = 1.45E-06). Through a comprehensive fine-scale-mapping SNP-selection procedure, 137 additional SNPs in a 668 kb region from MEGF9 to STOM on 9q33.2 were chosen for follow-up genotyping in a staged-approach. Significant single marker results (Pcomb<0.01) spanned a large 525 kb region from FBXW2 to GSN. However, a variety of analyses identified SNPs in a 70 kb region extending from the third intron of PHF19 across TRAF1 into the TRAF1-C5 intergenic region, but excluding the C5 coding region, as the most interesting (trend Pcomb: 1.45E-06 → 5.41E-09). The observed association patterns for these SNPs had heightened statistical significance and a higher degree of consistency across sample sets. In addition, the allele frequencies for these SNPs displayed reduced variability between control groups when compared to other SNPs. Lastly, in combination with the other two known genetic risk factors, HLA-DRB1 and PTPN22, the variants reported here generate more than a 45-fold RA-risk differential

Love thy neighbor? Reciprocal impacts between plant community structure and insect herbivory in co-occurring Asteraceae

Patterns of herbivory may vary with fine?scale plant community structure: the degree of damage plants experience may depend on their neighbors (i.e., associational resistance or susceptibility). Differential herbivory, in turn, may facilitate a shift in plant community structure. We investigated these reciprocal effects of plant community structure and insect herbivory in a field mesocosm experiment with closely related, native Asteraceae that co?occur in early?successional habitats (old fields). After one year of establishment, we excluded or augmented insect herbivores for two years in equal?density communities of three types: goldenrod?dominated (Solidago spp.) or aster?dominated (Symphyotrichum spp.) congeneric communities and mixtures of the two genera. In manipulated outbreaks, overall and species?specific patterns of herbivory by the main herbivore, the leaf beetle Trirhabda virgata, varied dramatically with community composition. In both years, the preferred goldenrods suffered 25?70% higher defoliation in mixtures with the less?preferred asters (i.e., associational susceptibility), compared to when growing with congeners; in contrast, asters experienced lower damage in mixtures (i.e., associational resistance). Insect herbivory consistently reduced overall plant productivity, and promoted colonization by other old?field species. Importantly, herbivory also initiated a shift in the structure of the plant communities, and this effect depended on the starting community composition, implying potential reciprocal effects. For instance, only in mixtures did elevated herbivory reduce the proportional abundance of the preferred host, and the old?field dominant, Solidago altissima. Our findings underscore the importance of plant community composition for variation in and impacts of herbivory and suggest the possibility of feedbacks between herbivory and local community structure as one of the mechanisms contributing to the maintenance of vegetation heterogeneity.Funding was provided by Cornell's Biogeochemistry and Environmental Biocomplexity Small Grant (DGE 0221658), Andrew W. Mellon Student Research Grant, and NSF?DEB 1118783 (A. A. Agrawal). M. Stastny was supported by the Postgraduate Scholarship from the National Science and Engineering Research Council (NSERC) of Canada during the course of this study

Ecological Consequences Of Relatedness: The Role Of Competition And Herbivory In The Community Structure Of Co-Occurring Asteraceae

Species interactions, such as competition and herbivory, are believed to be important structuring forces in plant communities. As a proxy for species similarity, the degree of relatedness among species may influence the intensity and outcomes of these interactions. In my dissertation research, I examined whether relatedness influenced the relative importance of plant competition and insect herbivory, and their feedbacks, in structuring the local community of closely related Asteraceae. Focusing on seven common, co-occurring, old-field species (genus Solidago, Symphyotrichum, and Euthamia), I tested the long-standing hypothesis that competition between close relatives is stronger than among more distantly related taxa. I also examined the effects of plant community structure on herbivory by a specialist outbreaking herbivore (Trirhabda virgata), and, in turn, the impacts of herbivory on plant competitive dynamics and community structure. Relatedness was not a reliable predictor of the intensity of competition among the focal species. Outcomes of pairwise competition between close and more distant relatives did not differ in a shortterm greenhouse experiment. Over three years, community productivity and growth of individual species were comparable in field mesocosms containing closely related species or mixtures of more distantly related taxa, in spite of clear differences in competitive abilities among species. However, communities of close relatives experienced greater invasion by other old-field species, highlighting the role of relatedness and competition in broader plant community structure. Community relatedness also determined the extent of damage by Trirhabda, which reflected the insect's host preference hierarchy. Specifically, the preferred genus (Solidago) suffered greater herbivory when growing in mixtures with the less preferred genus (Symphyotrichum) than when growing alone; the opposite pattern was observed for Symphyotrichum. In spite of differential damage, herbivory did not lead to a shift in the competitive abilities or community structure of the focal species compared to communities protected from herbivores; however, insect herbivores promoted invasion of the communities by other old-field species. In summary, my research reveals the consequences of species relatedness in trophic interactions between plants and herbivores, but not directly in plant competition, and underscores the potential feedbacks between plant community structure and herbivory over longer time scales

Empirical Evidence on Growth and Volatility

This paper empirically investigates the relationship between long-run economic growth and output volatility. There is an emerging theoretical literature on the topic which is inconclusive on the size and direction of the relationship. We analyze this relationship empirically for the time series experience of 21 OECD countries between the years 1961 and 2005. After applying a pooled OLS estimator and a series of robustness checks we conclude that there is strong empirical evidence for a positive relationship between output variability and economic growth

Data from: Evidence for rapid evolutionary change in an invasive plant in response to biological control

We present evidence that populations of an invasive plant species that have become re-associated with a specialist herbivore in the exotic range through biological control have rapidly evolved increased anti-herbivore defences compared to populations not exposed to biocontrol. We grew half-sib families of the invasive plant Lythrum salicaria sourced from 17 populations near Ottawa, Canada, that differed in their history of exposure to a biocontrol agent, the specialist beetle Neogalerucella calmariensis. In a greenhouse experiment, we manipulated larval and adult herbivory to examine whether a population's history of biocontrol influenced plant defence and growth. Plants sourced from populations with a history of biocontrol suffered lower defoliation than naïve, previously unexposed populations, strongly suggesting they had evolved higher resistance. Plants from biocontrol-exposed populations were also larger and produced more branches in response to herbivory, regrew faster even in the absence of herbivory, and were better at compensating for the impacts of herbivory on growth (i.e., they exhibited increased tolerance). Furthermore, resistance and tolerance were positively correlated among genotypes with a history of biocontrol but not among naïve genotypes. Our findings suggest that biocontrol can rapidly select for increased defences in an invasive plant, and may favour a mixed defence strategy of resistance and tolerance without an obvious cost to plant vigour. While rarely studied, such evolutionary responses in the target species have important implications for the long-term efficacy of biocontrol programmes