Highway and runway traction studies - The problem, history, objectives, and NASA program

Review of highway and runway traction studie

An investigation of environmental factors associated with the current and proposed jetty systems at Belle Pass, Louisiana

The history of the existing jetty system at Belle Pass was investigated to determine its past effect on the littoral currents and beach erosion. Present flow patterns and erosion rates were also studied, along with the prevailing recession rates of local beaches not influenced by the jetty system. Aerial photographs and maps were used in conjunction with periodic hydraulic measurements, ground observations, and physical measurements of beach erosion. A scale model was constructed to further the study of flow patterns and velocities. It is shown that the existing jetty has not adversely affected the coastline in the area; erosive processes have been retarded by the jetty and its companion groin. Future erosion patterns are predicted, and projected effects of the proposed jetty system are given

SIK2 Restricts Autophagic Flux To Support Triple-Negative Breast Cancer Survival

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease with multiple, distinct molecular subtypes that exhibit unique transcriptional programs and clinical progression trajectories. Despite knowledge of the molecular heterogeneity of the disease, most patients are limited to generic, indiscriminate treatment options: cytotoxic chemotherapy, surgery, and radiation. To identify new intervention targets in TNBC, we used large-scale, loss-of-function screening to identify molecular vulnerabilities among different oncogenomic backgrounds. This strategy returned salt inducible kinase 2 (SIK2) as essential for TNBC survival. Genetic or pharmacological inhibition of SIK2 leads to increased autophagic flux in both normal-immortalized and tumor-derived cell lines. However, this activity causes cell death selectively in breast cancer cells and is biased toward the claudin-low subtype. Depletion of ATG5, which is essential for autophagic vesicle formation, rescued the loss of viability following SIK2 inhibition. Importantly, we find that SIK2 is essential for TNBC tumor growth in vivo . Taken together, these findings indicate that claudin-low tumor cells rely on SIK2 to restrain maladaptive autophagic activation. Inhibition of SIK2 therefore presents itself as an intervention opportunity to reactivate this tumor suppressor mechanism

High spectral resolution time-resolved optical spectroscopy of V893 Sco

We present high resolution time-resolved optical spectra of the high inclination short orbital period dwarf nova V893 Sco. We performed spectral analysis through radial velocity measurements, Doppler mapping, and ratioed Doppler maps. Our results indicate that V893 Sco's accretion disk is dissimilar to WZ Sge's accretion disk, and does not fit any of the current accretion disk models. We derive the system parameters M1 and i, and present evidence for V893 Sco as a very young cataclysmic variable and an ER UMa star. We advance the hypothesis that all ER UMa stars may be newly formed cataclysmic variables.Comment: 23 pages (total), 8 figures, accepted by Ap

Detection of orbital and superhump periods in Nova V2574 Ophiuchi (2004)

We present the results of 37 nights of CCD unfiltered photometry of nova V2574 Oph (2004) from 2004 and 2005. We find two periods of 0.14164 d (~3.40 h) and 0.14773 d (~3.55 h) in the 2005 data. The 2004 data show variability on a similar timescale, but no coherent periodicity was found. We suggest that the longer periodicity is the orbital period of the underlying binary system and that the shorter period represents a negative superhump. The 3.40 h period is about 4% shorter than the orbital period and obeys the relation between superhump period deficit and binary period. The detection of superhumps in the light curve is evidence of the presence of a precessing accretion disk in this binary system shortly after the nova outburst. From the maximum magnitude - rate of decline relation, we estimate the decay rate t_2 = 17+/-4 d and a maximum absolute visual magnitude of M_Vmax = -7.7+/-1.7 mag.Comment: 6 pages, 6 figures, 2 .sty files, AJ accepted, minor change to one of reference

Photometry of VS0329+1250: A New, Short-Period SU Ursae Majoris Star

Time-resolved CCD photometry is presented of the recently-discovered (V~15 at maximum light) eruptive variable star in Taurus, which we dub VS0329+1250. A total of ~20 hr of data obtained over six nights reveals superhumps in the light curves, confirming the star as a member of the SU UMa class of dwarf novae. The superhumps recur with a mean period of 0.053394(7) days (76.89 min), which represents the shortest superhump period known in a classical SU UMa star. A quadratic fit to the timings of superhump maxima reveals that the superhump period was increasing at a rate given by dP/dt ~ (2.1 +/- 0.8) x 10^{-5} over the course of our observations. An empirical relation between orbital period and the absolute visual magnitude of dwarf novae at maximum light, suggests that VS0329+1250 lies at a distance of ~1.2 +/- 0.2 kpc.Comment: V2 - The paper has been modified to incorporate the referee's comments, and has now been accepted for publication in the PASP. The most significant change is that we are now able to confirm that the superhump period was increasing during the course of our observation

What Our Hands Say: Exploring Gesture Use in Subgroups of Children With Language Delay

Purpose The aim of this study was to investigate whether children with receptive-expressive language delay (R/ELD) and expressive-only language delay (ELD) differ in their use of gesture; to examine relationships between their use of gesture, symbolic comprehension, and language; to consider implications for assessment and for the nature of problems underlying different profiles of early language delay. Method Twelve children with ELD (8 boys, 4 girls) and 10 children with R/ELD (8 boys, 2 girls), aged 2–3 years, were assessed on measures of gesture use and symbolic comprehension. Results Performance of the R/ELD group was significantly poorer than performance of the ELD group on measures of gesture and symbolic comprehension. Gesture use and symbolic comprehension were significantly associated with receptive language, but associations with expressive language were not significant. Conclusions Findings of this study support previous research pointing to links between gesture and language development, and more specifically, between delays in gesture, symbolic understanding, and receptive rather than expressive language. Given potentially important implications for the nature of problems underlying ELD and R/ELD, and for assessment of children with language delay, this preliminary study invites further investigation comparing the use of different gesture types in samples of children matched on age and nonverbal IQ

Development and Validation of the Microbiology for Health Sciences Concept Inventory

Identifying misconceptions in student learning is a valuable practice for evaluating student learning gains and directing educational interventions. By accurately identifying students’ knowledge and misconceptions about microbiology concepts, instructors can design effective classroom practices centered on student understanding. Following the development of ASM’s Curriculum Guidelines in 2012, we developed a concept inventory, the Microbiology for Health Sciences Concept Inventory (MHSCI), that measures learning gains and identifies student misconceptions in health sciences microbiology classrooms. The 23-question MHSCI was delivered to a wide variety of students at multiple institution types. Psychometric analysis identified that the MHSCI instrument is both discriminatory and reliable in measuring student learning gains. The MHSCI results correlated with course outcomes, showing the value of using the instrument alongside course level assessments to measure student learning. The MHSCI is a reliable and efficient way to measure student learning in microbiology and can be used both as a faculty development tool and an effective student assessment tool

Differential cell responses to nanoparticle docetaxel and small molecule docetaxel at a sub-therapeutic dose range

Current preclinical evaluations of nanoparticle taxanes have focused on the effect of nanoparticle size and shape on the efficacy and toxicity. It is generally assumed that nanoparticle therapeutics have the same cellular response on tumor and normal cells as their small molecule counterparts. Here, we show that nanoparticle taxanes can mediate cellular effects distinct from that of small molecule taxanes at the sub-therapeutic dose range. Cells that are exposed to two polymeric nanoparticle formulations of docetaxel were found to undergo a different cell cycle and cell fate than that of cells that were exposed to small molecule docetaxel. Our results suggest that nanoparticle formulation of therapeutics can affect the therapeutic effect of its cargo

Timing Analysis of the Light Curve of the Dipping-Bursting X-ray Binary X1916-053

We present the timing analysis results for our observations of the x-ray dip source X1916-053 conducted with RXTE between February and October of 1996. Our goal was to finally measure the binary period - as either the x-ray dip period or ~1% longer optical modulation period, thereby establishing if the binary has a precessing disk (SU UMa model) or a third star (triple model). Combined with historical data (1979-96), the x-ray dip period is measured to be 3000.6508 $\pm$ 0.0009 sec with a 2$\sigma$ upper limit $|\dot P| \leq 2.06 \times 10^{-11}$. From our quasi-simultaneous optical observations (May 14-23, 1996) and historical data (1987-96), we measure the optical modulation period to be 3027.5510 $\pm$ 0.0052 sec with a 2$\sigma$ upper limit $|\dot P| \leq 2.28 \times 10^{-10}$. The two periods are therefore each stable (over all recorded data) and require a $3.9087 \pm 0.0008$d beat period. This beat period, and several of its harmonics is also observed as variations in the dip shape. Phase modulation of x-ray dips, observed in a 10 consecutive day observation, is highly correlated with the $\sim$3.9d dip shape modulation. The 1987-1996 optical observations show that the optical phase fluctuations are a factor of 3 larger than those in the x-ray. We discuss SU UMa vs. triple models to describe the X1916-053 light curve behavior and conclude that the x-ray dip period, with smaller phase jitter, is probably the binary period so that the required precession is most likely similar to that observed in SU UMa and x-ray nova systems. However the ``precession'' period stability and especially the fact that the times of x-ray bursts may partially cluster to occur just after x-ray dips, continue to suggest that this system may be a hierarchical triple.Comment: 33 pages, 13 figures, accepted by Ap