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

Low Energy Electron Point Projection Microscopy of Suspended Graphene, the Ultimate "Microscope Slide"

Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the covalent radius of sp^2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 +/- 0.6 Angstroms for the electron emitter. It is demonstrated that graphene can be used as both anode and substrate in PPM in order to avoid distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography

The Admissions Process in Occupational Therapy Education: Investigating Academic and Non-academic Metrics in the Applicant Selection Process

The overall goal for any admissions process is to analyze criteria and identify the prospective students that have the highest potential for success in the program’s curriculum and in the field as a practicing clinician. The purpose of this study was to examine common academic and non-academic criteria utilized in occupational therapy (OT) admission processes and determine what criteria are used by programs with 100% student pass ratings on their National Board for Certification in Occupational Therapy (NBCOT) exam following completion of an OT program. Admissions criteria components and NBCOT pass rates were collected from the top 107 OT programs, as reported by US News and World Report, using publicly available websites for each program and the NBCOT webpage. Descriptive statistics were recorded regarding the frequency of utilizing various admissions criteria. Chi-square tests were utilized to examine the relationship between each admissions criteria component and the NBCOT pass rate. Admissions criteria frequently utilized by the top OT programs included a bachelor’s degree prior to matriculation (90.99% programs), minimum undergraduate GPA (55.86%), personal statement (90.09%), letters of recommendation (97.30%), observation hours (74.77%), and an interview (61.26%). Few programs required applicants to submit a minimum math/science GPA (11.71%) or a writing sample (40.54%). Results did not reveal a statistically significant difference between analyzed criteria groups. It is likely that NBCOT pass rates are impacted by other factors that were not publicly available or included in this study

Ion measurements during Pioneer Venus reentry: Implications for solar cycle variation of ion composition and dynamics

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95616/1/grl7044.pd

Steps to Growing Up Healthy: a Pediatric Primary Care Based Obesity Prevention Program for Young Children

Background Leading medical organizations have called on primary care pediatricians to take a central role in the prevention of childhood obesity. Weight counseling typically has not been incorporated into routine pediatric practice due to time and training constraints. Brief interventions with simple behavior change messages are needed to reach high-risk children, particularly Latino and Black children who are disproportionately affected by obesity and related comorbidities. Steps to Growing Up Healthy (Added Value) is a randomized controlled trial testing the efficacy of brief motivational counseling (BMC) delivered by primary care clinicians and the added value of supplementing BMC with monthly contact by community health workers (CHW) in the prevention/reversal of obesity in Latino and Black children ages 2-4 years old. Methods/Design Mother-child dyads (targeted n=150) are recruited for this 12-month randomized trial at an inner-city pediatric primary care clinic and randomized to: 1) BMC delivered by clinicians and nurses at well, sick, and WIC visits with the goal of reducing obesogenic behaviors (BMC); 2) BMC plus monthly phone calls by a CHW (BMC+Phone); or 3) BMC plus monthly home visits by a CHW (BMC+Home). During BMC, the medical team facilitates the selection of a specific goal (i.e., reduce sugar sweetened beverage consumption) that is meaningful to the mother and teaches the mother simple behavioral strategies. Monthly contacts with CHWs are designed to identify and overcome barriers to goal progress. Dyads are assessed at baseline and 12 months and the primary outcome is change in the child’s BMI percentile. We hypothesize that BMC+Phone and BMC+Home will produce greater reductions in BMI percentiles than BMC alone and that BMC+Home will produce greater reductions in BMI percentiles than BMC+Phone. Discussion Steps to Growing Up Healthy will provide important information about whether a brief primary care-based intervention that utilizes a motivational interviewing and goal setting approach can be incorporated into routine care and is sufficient to prevent/reverse obesity in young children. The study will also explore whether monthly contact with a community health worker bridges the gap between the clinic and the community and is an effective strategy for promoting obesity prevention in high-risk families

Nanoscale structuring of tungsten tip yields most coherent electron point-source

This report demonstrates the most spatially-coherent electron source ever reported. A coherence angle of 14.3 +/- 0.5 degrees was measured, indicating a virtual source size of 1.7 +/-0.6 Angstrom using an extraction voltage of 89.5 V. The nanotips under study were crafted using a spatially-confined, field-assisted nitrogen etch which removes material from the periphery of the tip apex resulting in a sharp, tungsten-nitride stabilized, high-aspect ratio source. The coherence properties are deduced from holographic measurements in a low-energy electron point source microscope with a carbon nanotube bundle as sample. Using the virtual source size and emission current the brightness normalized to 100 kV is found to be 7.9x10^8 A/sr cm^2

Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit

The bright M dwarf K2-18 at 34 pc is known to host a transiting super-Earth-sized planet orbiting within the star's habitable zone; K2-18b. Given the superlative nature of this system for studying an exoplanetary atmosphere receiving similar levels of insolation as the Earth, we aim to characterize the planet's mass which is required to interpret atmospheric properties and infer the planet's bulk composition. We obtain precision radial velocity measurements with the HARPS spectrograph and couple those measurements with the K2 photometry to jointly model the observed radial velocity variation with planetary signals and a radial velocity jitter model based on Gaussian process regression. We measure the mass of K2-18b to be $8.0 \pm 1.9$ M$_{\oplus}$ with a bulk density of $3.7 \pm 0.9$ g/cm$^3$ which may correspond to a predominantly rocky planet with a significant gaseous envelope or an ocean planet with a water mass fraction $\gtrsim 50$%. We also find strong evidence for a second, warm super-Earth K2-18c at $\sim 9$ days with a semi-major axis 2.4 times smaller than the transiting K2-18b. After re-analyzing the available light curves of K2-18 we conclude that K2-18c is not detected in transit and therefore likely has an orbit that is non-coplanar with K2-18b. A suite of dynamical integrations with varying simulated orbital eccentricities of the two planets are used to further constrain each planet's eccentricity posterior from which we measure $e_b < 0.43$ and $e_c < 0.47$ at 99% confidence. The discovery of the inner planet K2-18c further emphasizes the prevalence of multi-planet systems around M dwarfs. The characterization of the density of K2-18b reveals that the planet likely has a thick gaseous envelope which along with its proximity to the Solar system makes the K2-18 planetary system an interesting target for the atmospheric study of an exoplanet receiving Earth-like insolation.Comment: 13 pages, 8 figures including 4 interactive figures best viewed in Adobe Acrobat. Submitted to Astronomy & Astrophysics. Comments welcom

Social influence and moment-to-moment changes in young adults’ mood and psychotic symptoms

Background: • Social situations can have a significant impact on young people’s mood and mental experiences. • More specifically, we want to know how someone’s perceived social influence in social situations relates to their mood and psychotic symptoms. • Past studies have found connections between lower perceived social status (rank, comparison, and related concepts) and psychotic symptoms anxiety, depression, and other mood related psychopathology. • We use experience sampling methods to capture moment-to-moment changes in mood and psychotic symptoms in a variety of social settings

Low inbreeding and high pollen dispersal distances in populations of two Amazonian Forest tree species.

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