Prospects for detecting the Rossiter-McLaughlin effect of Earth-like planets: the test case of TRAPPIST-1b and c

The Rossiter-McLaughlin effect is the principal method of determining the sky-projected spin--orbit angle ($\beta$) of transiting planets. Taking the example of the recently discovered TRAPPIST-1 system, we explore how ultracool dwarfs facilitate the measurement of the spin--orbit angle for Earth-sized planets by creating an effect that can be an order of magnitude more ample than the Doppler reflex motion caused by the planet if the star is undergoing rapid rotation. In TRAPPIST-1's case we expect the semi-amplitudes of the Rossiter-McLaughlin effect to be $40-50$ m/s for the known transiting planets. Accounting for stellar jitter expected for ultracool dwarfs, instrumental noise, and assuming radial velocity precisions both demonstrated and anticipated for upcoming near-infrared spectrographs, we quantify the observational effort required to measure the planets' masses and spin--orbit angles. We conclude that if the planetary system is well-aligned then $\beta$ can be measured to a precision of $\lesssim 10^{\circ}$ if the spectrograph is stable at the level of 2 m/s. We also investigate the measure of $\Delta \beta$, the mutual inclination, when multiple transiting planets are present in the system. Lastly, we note that the rapid rotation rate of many late M-dwarfs will amplify the Rossiter-McLaughlin signal to the point where variations in the chromatic Rossiter-McLaughlin effect from atmospheric absorbers should be detectable.Comment: 11 pages, 4 figures. Accepted to MNRAS. Comments welcom

Requirement for Slit-1 and Robo-2 in zonal segregation of olfactory sensory neuron axons in the main olfactory bulb

The formation of precise stereotypic connections in sensory systems is critical for the ability to detect and process signals from the environment. In the olfactory system, olfactory sensory neurons (OSNs) project axons to spatially defined glomeruli within the olfactory bulb (OB). A spatial relationship exists between the location of OSNs within the olfactory epithelium (OE) and their glomerular targets along the dorsoventral axis in the OB. The molecular mechanisms underlying the zonal segregation of OSN axons along the dorsoventral axis of the OB are poorly understood. Using robo-2/ (roundabout) and slit-1/ mice, we examined the role of the Slit family of axon guidance cues in the targeting of OSN axons during development. We show that a subset of OSN axons that normally project to the dorsal region of the OB mistarget and form glomeruli in the ventral region in robo-2/ and slit-1/ mice. In addition, we show that the Slit receptor, Robo-2, is expressed in OSNs in a high dorsomedial to low ventrolateral gradient across the OE and that Slit-1 and Slit-3 are expressed in the ventral region of the OB. These results indicate that the dorsal-to-ventral segregation of OSN axons are not solely defined by the location of OSNs within the OE but also relies on axon guidance cues

Dose-related sex differences in the establishment of conditioned disgust (anticipatory nausea), and the effect of peripubertal and adult immune system stimulation with the endotoxin lipopolysaccharide (LPS) on learning and memory in the rat

This thesis examined sex differences in the establishment of lithium chloride (LiCl) – induced conditioned disgust behavior (anticipatory nausea) to a distinct context, as well as, the establishment of conditioned place avoidance (CPA) using rodent models. Also examined were potential sex differences in response to treatment with the bacterial endotoxin, lipopolysaccharide (LPS), and its effect on learning and memory. In Chapter 2, male and female naïve Long-Evans rats were injected (intraperitoneally; i.p.) with either 200 µg/kg LPS or 0.9% (NaCl), 90 minutes prior to i.p. injections of either 128 mg/kg LiCl or 0.9% NaCl, and immediately placed into a distinctive context for 30 minutes (repeated over 4 conditioning days, spaced 72 h apart). 72 h following the final conditioning day, each subject was re-exposed to the context on a drug-free test day where orofacial and somatic behaviors were recorded. Results showed that LiCl-treated females conditioned stronger disgust reactions, relative to LiCl-treated males, as evidenced by significantly higher frequencies of conditioned “gaping” behavior and forelimb flailing in females. Pre-treatment with LPS during conditioning led to strong inhibition of conditioned disgust behavior, to levels that did not significantly differ from controls. Although there was no apparent sex difference in the degree of inhibition produced by LPS in this context-based rodent disgust model, males did exhibit significantly greater 24 h body weight losses following LPS injections on the first two conditioning days, relative to females. In Chapter 3, the sex difference in conditioned gaping behavior found in Chapter 2 was explored further by examining potential dose-related effects. Once again, females displayed significantly higher frequencies of conditioned “gaping” behavior relative to males, in a dose-dependent manner. The results from Chapters 2 and 3 provide strong support for a sex difference in the onset and severity of nausea-related symptoms which is also observed among the human population. This provides a preclinical tool for testing the efficacy of anti-nausea treatments and noxious drug side-effects. In Chapter 4, the effects of LPS pretreatment on the establishment of conditioned place avoidance (CPA) were examined. Female rats were also injected with LPS or saline during the peripubertal phase of development (6 weeks of age) and later pretreated with LPS again or saline in the classic two-chamber CPA paradigm. Results showed that while peripubertal LPS had no long-term effect on establishing CPA, it did interfere with the ability of a second LPS challenge in adulthood to block CPA, as was shown in subjects pretreated with LPS in adulthood only. The results of this study provide support for previous findings that suggest that stressors and/or immune challenges during this sensitive period of development can lead to long-lasting alterations in behavior

The Effective Use of Coal Combustion Products (CCPs) in Ashphalt Pavements

Hot-Mix Asphalt (HMA) is one of the most widely used construction materials. The National Asphalt Paving Association (NAPA) estimated that there are over 2.6 million miles of roadway surfaces paved in the United States and 94% of these roads are paved with asphalt. NAPA also estimates that approximately 550 million tons of asphalt worth over $30 billion a year is produced in the United States. At such a huge production rate, innovative solutions need to be developed so that asphalt pavements last longer and can also reduce the production and maintenance costs. Producing sustainable asphalt materials can provide for improved infrastructure which is required for the operational needs of society. Coal Combustion Products (CCPs), such as fly ash materials, are by-products of the coal combustion process. Fly ash is one of the most commonly used by-product pozzolan. These materials are unique in that they have a spherical shape and the small spherical particles can improve the workability and reduce the porosity when mixed with other binding materials. In 2006, the American Coal Ash Association (ACAA) reported that there has been 72.4 million tons of coal ash produced in which only about 52,608 tons of fly ash was used as mineral fillers in asphalt applications. Since 2006, there has been no data on the use of fly ash in asphalt applications. Researchers have found beneficial uses of fly ash in asphalt mastics and asphalt pavements. However, this research has been limited to older testing procedures and only few researchers have reported on the effects of CCPs in asphalt using Superpave® protocol. By further systematic investigation of the effect of CCPs in asphalt, better conclusions can be made regarding the potential favorable effects of CCPs in asphalt. This research investigated the effects of CCPs in asphalt mixtures in terms of asphalt film thickness, workability, aging resistance, moisture damage resistance, intermediate-temperature fatigue cracking resistance, and low-temperature thermal cracking resistance. Control mixtures (5.5% binder content) were compared to ASHphalt mixtures with a 10% (by mass) binder replacement with CCP. The CCPs used were a WE05 (Class C), TA11 (Class F), LG14 (Class F), and SF15 (SDA – Spray Dryer Absorber material). For the Control and ASHphalt mixtures, it was verified that no major differences were observed or recorded for aggregate coating quality or mixing performance. Compaction efforts were reduced for ASHphalt mixtures (compacted at 145oC) as compared to the Control mixtures (compacted at 140oC). The minor increase in compaction temperature was negligible but was necessary to reduce the material viscosity so that compaction efforts were more comparable to the Control mixtures. The addition of CCPs resulted in an enhanced aging resistance for mixtures with LG14 (F) and SF15 (SDA). Indirect Tensile Testing (IDT) proved that the ASHphalt mixtures developed higher strengths than the Control mixtures, especially for WE05 (C) and TA11 (F) mixtures. Moisture damage resistance was evaluating using Tensile Strength Ratio (TSR) and it was discovered that all ASHphalt samples, especially LG14 (F), developed a better TSR than the Control samples. Fatigue testing was performed at intermediate temperatures (20 ± 1oC) to evaluate the number of cycles each sample could withstand before a drop in E* (Complex Modulus). Every ASHphalt material performed better than the Control mixtures for fatigue testing, especially TA11 (F) mixtures as this material withstood 149,250 cycles before failure with a vertical deformation rate of 6.52E-06 mm/cycle. Thermal cracking resistance was evaluated at low temperatures (-18 ± 1oC) by using the Semi-Circular Bending (SCB) test. For Fracture Energy (Gf) all ASHphalt mixtures performed better than the Control mixture, specifically LG14 (F) as this mixture performed the best. For Fracture Toughness (KIC), only LG14 (F) performed better than the Control mixture. Lastly, all mixtures demonstrated lower Stiffness (S) values, especially TA11 (F), than the Control mixture and this was desirable

A modified leaf disk method for rearing predaceous mites [Acarina : Phytoseiidae]

La méthode du disque foliaire coupé pour élever des phytoséiides a été modifiée en maintenant le disque foliaire sur une solution nutritive solidifiée avec de l'agar. L'acarien prédateur Amblyseius cucumeris et sa proie, le thrips Frankliniella occidentalis, ont été élevés avec succès sur ce milieu. La survie et le temps de rétention du prédateur sur agar étaient meilleurs que sur de la ouate. L'agar a prolongé la qualité du feuillage pour la survie des larves de thrips comparé à la ouate et à l'eau, tout en offrant plusieurs autres avantages par rapport à ces milieux.The detached leaf disk method for rearing phytoseiids was modified by maintaining leaf disks on a nutrient solution solidified with agar. The predaceous mite, Amblyseius cucumeris, and thrips prey, Frankliniella occidentalis, were successfully reared on cucumber leaf disks using this technique. Predator survival and retention time on agar as the leaf supporting medium were improved compared to cotton wool. Agar prolonged leaf disk quality for thrips survival compared to both cotton wool and water, while offering other significant advantages to these alternative media

A Deep Spitzer Survey of Circumstellar Disks in the Young Double Cluster, h and chi Persei

We analyze very deep IRAC and MIPS photometry of $\sim$ 12,500 members of the 14 Myr old Double Cluster, h and $\chi$ Persei, building upon on our earlier, shallower Spitzer studies (Currie et al. 2007a, 2008a). Numerous likely members show infrared (IR) excesses at 8 {\mu}m and 24 $\mu$m indicative of circumstellar dust. The frequency of stars with 8 $\mu$m excess is at least 2% for our entire sample, slightly lower (higher) for B/A stars (later type, lower-mass stars). Optical spectroscopy also identifies gas in about 2% of systems but with no clear trend between the presence of dust and gas. Spectral energy distribution (SED) modeling of 18 sources with detections at optical wavelengths through MIPS 24 $\mu m$ reveals a diverse set of disk evolutionary states, including a high fraction of transitional disks, although similar data for all disk-bearing members would provide better constraints. We combine our results with those for other young clusters to study the global evolution of dust/gas disks. For nominal cluster ages, the e-folding times ($\tau_{o}$) for the frequency of warm dust and gas are 2.75 Myr and 1.75 Myr respectively. Assuming a revised set of ages for some clusters (e.g. Bell et al. 2013), these timescales increase to 5.75 and 3.75 Myr, respectively, implying a significantly longer typical protoplanetary disk lifetime. The transitional disk duration, averaged over multiple evolutionary pathways, is $\sim$ 1 Myr. Finally, 24 $\mu$m excess frequencies for 4-6 M$_{\odot}$ stars appear lower than for 1-2.5 M$_{\odot}$ stars in other 10-30 Myr old clusters.Comment: 35 pages, 6 tables, 21 figures; Accepted for publication in The Astrophysical Journa

Guidelines for physical weed control research: flame weeding, weed harrowing and intra-row cultivation

A prerequisite for good research is the use of appropriate methodology. In order to aggregate sound research methodology, this paper presents some tentative guidelines for physical weed control research in general, and flame weeding, weed harrowing and intra-row cultivation in particular. Issues include the adjustment and use of mechanical weeders and other equipment, the recording of impact factors that affect weeding performance, methods to assess effectiveness, the layout of treatment plots, and the conceptual models underlying the experimental designs (e.g. factorial comparison, dose response). First of all, the research aims need to be clearly defined, an appropriate experimental design produced and statistical methods chosen accordingly. Suggestions on how to do this are given. For assessments, quantitative measures would be ideal, but as they require more resources, visual classification may in some cases be more feasible. The timing of assessment affects the results and their interpretation. When describing the weeds and crops, one should list the crops and the most abundantly present weed species involved, giving their density and growth stages at the time of treatment. The location of the experimental field, soil type, soil moisture and amount of fertilization should be given, as well as weather conditions at the time of treatment. The researcher should describe the weed control equipment and adjustments accurately, preferably according to the prevailing practice within the discipline. Things to record are e.g. gas pressure, burner properties, burner cover dimensions and LPG consumption in flame weeding; speed, angle of tines, number of passes and direction in weed harrowing. The authors hope this paper will increase comparability among experiments, help less experienced scientists to prevent mistakes and essential omissions, and foster the advance of knowledge on non-chemical weed management