Plant community development after twelve growing seasons in two experimental wetland basins

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It All Adds Up: Examining and Enhancing Campus Climate for Affordability at a Four-Year University

This study examined undergraduate students’ perceptions of non-academic spending in college and how they navigated these expenses. Using a mixed-methods study at a public comprehensive university in the southeastern United States, we conceptualized these perceptions as a central component of campus climate for affordability in college. Findings demonstrated that campus policies, practices, and spaces facilitated non-academic spending and exacerbated students’ perceptions that college is unaffordable. Non-academic and social costs were more expensive than students anticipated, and many students struggled to manage their money and cover these costs. Students shared a range of strategies to navigate non-academic expenses, from opting out of social activities to forgoing savings and loan payments. These findings draw attention to policies and practices in higher education that problematize institutions’ commitment to affordability

The ion environment near Europa and its role in surface energetics

This paper gives the composition, energy spectra, and time variability of energetic ions measured just upstream of Europa. From 100 keV to 100 MeV, ion intensities vary by less than a factor of ∼5 among Europa passes considered between 1997 and 2000. We use the data to estimate the radiation dose rate into Europa's surface for depths 0.01 mm – 1 m. We find that in a critical fraction of the upper layer on Europa's trailing hemisphere, energetic electrons are the principal agent for radiolysis, and their bremsstrahlung photon products, not included in previous studies, dominate the dose below about 1 m. Because ion bombardment is more uniform across Europa's surface, the radiation dose on the leading hemisphere is dominated by the proton flux. Differences exist between this calculation and published doses based on the E4 wake pass. For instance, proton doses presented here are much greater below 1 mm

Flowering-pattern and yield components at inflorescence nodes of snap bean as affected by irrigation and plant density

This paper reports the results of a 2 x 2 factorial experiment on bush snap beans `Oregon 1604'. The treatments were 2 contrasted irrigation regimes and 2 contrasted plant densities, and were applied in 1978 and repeated in 1979. Data were collected on the number of flowers and pods, and pod size, at each node of the terminal inflorescence (6-T) of the main stem, and at each node of the oldest inflorescence (2-A) at Node 2. High and low plant densities were 45 and 18 plants m-2 in 1978 and 54 and 33 plants m-2 in 1979. High temperatures, frequently above 32[deg]C, prevailed during bloom and pod development in 1978, but for the most part occurred only during the week prior to bloom in 1979. Inflorescences 6-T and 2-A usually formed 4 and 3 RN's, respectively, in 1978 and 3 and 2 RN's in 1979. The flowers at the proximal nodes of each inflorescence all opened within a few days of one another (duration of flowering at proximal nodes between 3 and 5 days); the flowering-periods of adjacent nodes overlapped, and the flowering period increased acropetally within the inflorescence (duration of flowering at distal nodes between 7 and 13 days). In general, number of flowers, pods formed, pods harvested and percent set decreased acropetally within each inflorescence. The rate of acropetal decline was lessened by high irrigation or low plant density. In both years, high irrigation increased the percent set of all RN's of the 2-A inflorescences, but few other consistent effects between years were observed. The 2 most proximal RN's together produced 93% or more of the yield of each inflorescence. High irrigation significantly increased the total number of pods harvested from these RN's of inflorescences 6-T and 2-A, and low density had a similar effect on 2-A.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24846/1/0000272.pd

Can we use verbal estimation to dissect the internal clock? Differentiating the effects of pacemaker rate, switch latencies, and judgment processes

Behavioural timing is frequently assumed to be based on the accumulation of pulses from a pacemaker. In humans, verbal estimation is often used to determine whether the effect of factors which influence subjective time become more pronounced at longer durations - that is, if they affect the slope of the judgment function, consistent with a change in the rate of the pacemaker. Here, participants judged blank intervals marked by two squares which either did or did not differ in size. In Experiment 1, a small change in marker size produced shorter temporal judgments than a large change. This effect was independent of objective duration and indicates that the slope changes seen in previous work are not an inevitable artefact of the verbal estimation procedure. However, Experiments 2 and 3 included conditions where the markers did not change size and established (a) that the effect of marker size depends on the other stimuli presented during the experiment, and (b) that slope effects occur even when they cannot possibly be due to a change in the rate of the pacemaker. Taken together, these results urge some caution in the use of verbal estimation as a methodology for deconstructing the putative internal clock

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Abstract On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (\u3e2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased \u3e90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Key Points Substorm dynamics are important for highly relativistic electron energization Cold plasma preconditioning is significant for rapid relativistic energization Relativistic / highly relativistic electron energization can occur in \u3c 5 hrs

Science Objectives and Rationale for the Radiation Belt Storm Probes Mission

The NASA Radiation Belt Storm Probes (RBSP) mission addresses how populationsof high energy charged particles are created, vary, and evolve in space environments,and specifically within Earths magnetically trapped radiation belts. RBSP, with a nominallaunch date of August 2012, comprises two spacecraft making in situ measurements for atleast 2 years in nearly the same highly elliptical, low inclination orbits (1.1 5.8 RE, 10).The orbits are slightly different so that 1 spacecraft laps the other spacecraft about every2.5 months, allowing separation of spatial from temporal effects over spatial scales rangingfrom 0.1 to 5 RE. The uniquely comprehensive suite of instruments, identical on the twospacecraft, measures all of the particle (electrons, ions, ion composition), fields (E and B),and wave distributions (dE and dB) that are needed to resolve the most critical science questions.Here we summarize the high level science objectives for the RBSP mission, providehistorical background on studies of Earth and planetary radiation belts, present examples ofthe most compelling scientific mysteries of the radiation belts, present the mission design ofthe RBSP mission that targets these mysteries and objectives, present the observation andmeasurement requirements for the mission, and introduce the instrumentation that will deliverthese measurements. This paper references and is followed by a number of companionpapers that describe the details of the RBSP mission, spacecraft, and instruments