Temperature Effects on Development in \u3ci\u3eAphelinus Albipodus\u3c/i\u3e (Hymenoptera: Aphelinidae) From Two Geographic Regions

Aphelinus albipodus Hayat & Fatima was imported to the United States for classical biological control of the Russian wheat aphid, Diuraphis noxia (Mordvilko). Temperature effects on development of A. albipodus from two geographic regions (hereafter referred to as strains) were measured using the Russian wheat aphid as host. Temperature thresholds for egg to mummy, mummy to adult, and egg to adult development were 8.9,10.9, and 9.7°C for A. albipodus collected near Pingluo, China, and were and 8.5, 10.3, and 9.6°C for A. albipodus collected near Urumqi, China. The time required to develop from egg to adult did not differ among strains. However, when total immature development was partitioned into egg to mummy and mummy to adult, the time required for development through these two periods differed among strains. The Urumqi strain developed faster than the Pingluo strain from egg to mummy, while the Pingluo strain developed faster from mummy to adult. Degree-day requirements for egg to mummy development were 135 and 104 for the Pingluo and Urumqi strains, respectively. Corresponding requirements for mummy to adult development were 70 and 101 degree-days. The ability to vary immature development rate in response to climate or other factors could have adaptive significance because it would permit the parasitoid to exploit environments over a broad geographic range

Intrinsic and Cosmological Signatures in Gamma-Ray Burst Time Profiles: Time Dilation

The time profiles of many gamma-ray bursts consist of distinct pulses, which offers the possibility of characterizing the temporal structure of these bursts using a relatively small set of pulse shape parameters. We have used a pulse decomposition procedure to analyze the Time-to-Spill (TTS) data for all bursts observed by BATSE up through trigger number 2000, in all energy channels for which TTS data is available. We obtain amplitude, rise and decay timescales, a pulse shape parameter, and the fluences of individual pulses in all of the bursts. We investigate the correlations between brightness measures (amplitude and fluence) and timescale measures (pulse width and separation) which may result from cosmological time dilation of bursts, or from intrinsic properties of burst sources or from selection effects. The effects of selection biases are evaluated through simulations. The correlations between these parameters among pulses within individual bursts give a measure of the intrinsic effects while the correlations among bursts could result both from intrinsic and cosmological effects. We find that timescales tend to be shorter in bursts with higher peak fluxes, as expected from cosmological time dilation effects, but also find that there are non-cosmological effects contributing to this inverse correlation. We find that timescales tend to be longer in bursts with higher total fluences, contrary to what is expected from cosmological effects. We also find that peak fluxes and total fluences of bursts are uncorrelated, indicating that they cannot both be good distance indicators for bursts.Comment: 39 pages, 17 figures composed of 30 EPS files. Submitted to Astrophysical Journal. PostScript and PDF with un-bitmapped figures available at http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8365.html . Accompanies astro-ph/000221

Properties of Gamma-Ray Burst Time Profiles Using Pulse Decomposition Analysis

The time profiles of many gamma-ray bursts consist of distinct pulses, which offers the possibility of characterizing the temporal structure of these bursts using a relatively small set of pulse shape parameters. This pulse decomposition analysis has previously been performed on a small sample of bright long bursts using binned data from BATSE, which comes in several data types, and on a sample of short bursts using the BATSE Time-Tagged Event (TTE) data type. We have developed an interactive pulse-fitting program using the phenomenological pulse model of Norris, et al. and a maximum-likelihood fitting routine. We have used this program to analyze the Time-to-Spill (TTS) data for all bursts observed by BATSE up through trigger number 2000, in all energy channels for which TTS data is available. We present statistical information on the attributes of pulses comprising these bursts, including relations between pulse characteristics in different energy channels and the evolution of pulse characteristics through the course of a burst. We carry out simulations to determine the biases that our procedures may introduce. We find that pulses tend to have shorter rise times than decay times, and tend to be narrower and peak earlier at higher energies. We also find that pulse brightness, pulse width, and pulse hardness ratios do not evolve monotonically within bursts, but that the ratios of pulse rise times to decay times tend to decrease with time within bursts.Comment: 40 pages, 19 figures. Submitted to Astrophysical Journal. PostScript and PDF with un-bitmapped figures available at http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8364.html . Accompanying paper astro-ph/0002218 available at http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8365.htm

Sink or swim time? Social mobility and the 2021 Budget

Lee Elliot Major assesses the prospects for social mobility and economic recovery in Rishi Sunak’s 2021 Budget

Utilizing Criticality Stacks for Dynamic Voltage and Frequency Scaling

Thread imbalance is inevitable for multithreaded applications due to the necessity of synchronization primitives to coordinate access to memory and system resources. This imbalance leads to a bounding of application performance, but, more importantly for mobile devices, this imbalance also leads to energy inefficiencies. Recent works have begun to quantify this imbalance and look to leverage it not only for performance improvements, but for energy savings as well. All these works, though, test the theory through the use of simulators and power estimation tools. These results may show that the theory is sound, but the complexities of how a real machine handles synchronization may lead to diminished results by either having too large of a performance impact, or too little energy savings. In this work, we implement one such algorithm, PCSLB, and improve upon it in order to see if the results shown for this technique are feasible for use in real machines. With the improved algorithm, PCSLB-Max, and the CritScale Linux kernel module, we show that, in fact, there are energy saving available to us while mitigating the performance

Killing The Messenger: Exploring Novel Triggers For Messenger Rna Decay In Eukaryotes

The lifecycle of messenger RNAs is regulated by multiple layers beyond their primary sequence. In addition to carrying the information for protein synthesis, mRNAs are decorated with RNA binding proteins, marked with covalent chemical modifications, and fold into intricate secondary structures. However, the full set of information encoded by these “epitranscriptomic” layers is only partially understood, and is often only characterized for select transcripts. Thus, it is crucial to develop and apply transcriptome-wide analytical tools to probe the location and functional relevance of epitranscriptome features. In this dissertation, I focus on applying such methods toward better understanding determinants of mRNA stability, through using 1) High Throughput Annotation of Modified Nucleotides, 2) nuclease-mediated probing of RNA secondary structure, and 3) detection of partial mRNA degradation from RNA sequencing. I observe that chemical modifications tend to mark uncapped and small RNA fragments derived from mRNAs in plants and humans, suggesting a link between modifications and mRNA stability. I then show this link is direct through showing differential stability at Arabidopsis transcripts that change modification status during long-term salt stress. By probing secondary structure, I show a link between structure, smRNA production, and co-translational RNA decay. Finally, I develop a new in silico method to detect partial RNA degradation in mouse oocytes, and identify sequence elements that appear to block complete exonucleolytic transcript cleavage during meiosis. I then identify putative RNA binding proteins that might mediate this partial decay. In summary, I apply transcriptome-wide sequencing-based methods to survey the effects of covalent modifications, secondary structure, and RNA binding proteins on mRNA stability

A Bayesian localised conditional auto-regressive model for estimating the health effects of air pollution

Estimation of the long-term health effects of air pollution is a challenging task, especially when modeling spatial small-area disease incidence data in an ecological study design. The challenge comes from the unobserved underlying spatial autocorrelation structure in these data, which is accounted for using random effects modeled by a globally smooth conditional autoregressive model. These smooth random effects confound the effects of air pollution, which are also globally smooth. To avoid this collinearity a Bayesian localized conditional autoregressive model is developed for the random effects. This localized model is flexible spatially, in the sense that it is not only able to model areas of spatial smoothness, but also it is able to capture step changes in the random effects surface. This methodological development allows us to improve the estimation performance of the covariate effects, compared to using traditional conditional auto-regressive models. These results are established using a simulation study, and are then illustrated with our motivating study on air pollution and respiratory ill health in Greater Glasgow, Scotland in 2011. The model shows substantial health effects of particulate matter air pollution and nitrogen dioxide, whose effects have been consistently attenuated by the currently available globally smooth models