Biological Control Methods for Damping-off of Tomato Seedlings Caused by \u3cem\u3ePythium myriotylum\u3c/em\u3e

Pythium damping-off has the potential to cause severe loss in greenhouse and field grown tomatoes. Species of Pythium are found in soils from all climates, and capable of surviving for long periods without a host. Infectious structures of Pythium species are motile, and therefore able to travel through irrigation water and runoff. Pythium myriotylum thrives in warm, humid environments such as that of the Southeastern United States, and was thus chosen for this study. Currently, no tomato varieties with resistance to damping-off are available. In addition, the agriculture industry is striving for sustainable and biological methods of control of plant pests and pathogens. Therefore, biological controls that are capable of simultaneously protecting plants from pathogens and pests are needed. To that end, the first part of this investigation for biological control of tomato damping-off involves the seed application of an entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin, along with a commercial plant growth-promoting rhizobacteria formulation (BioYield) that is known to induce systemic resistance in plants to herbivores and pathogens, and a soil amendment with Monarda sp. containing essential oils that are fungicidal to many soilborne pathogens. The objectives of the first study were to determine the following: (i) if herbage of Monarda didyma used as a soil amendment is capable of suppressing damping-off of tomato seedlings; (ii) if conidia of Beauveria bassiana isolates used as seed coatings are capable of suppressing damping-off of tomato seedlings; (iii) if a commercial form of plant growth promoting rhizobacteria used as a seed drench is capable of suppressing damping-off of tomato seedlings; and (iv) if combinations of the herbage and the seed treatments are synergistic or antagonistic. Results from the first study indicated cultivar specificity with Beauveria bassiana and herbage treatments. Survival was increased in ‘Mountain Spring’ tomato seedlings treated with either B. bassiana 11-98 or BotaniGard when challenged with the pathogen, but no similar effects were observed in ‘Celebrity’ seedlings. There was also an increase in stem diameter in Beauveria-treated ‘Mountain Spring’ that was not seen in ‘Celebrity.’ When ‘Celebrity’ seedlings were grown in media amended with ‘Puerto Purification,’ there was a significant decrease in disease index when challenged with the pathogen. This effect was not observed in ‘Mountain Spring.’ ‘Violet Queen’ had negative effects on ‘Celebrity’ seedling growth, seen as a decrease of survival and increase in disease index. Treatment with PGPR had no significant effects in either cultivar. The second part of this research investigated dried, ground leaves (herbage) from 16 Monarda varieties as amendments for biological control against Pythium damping-off in tomato. The objectives of this study were to determine the following: (i) if Monarda essential oil constituents could inhibit growth of P. myriotylum in vitro; (ii) if herbage amendments could suppress Pythium damping-off; (iii) if herbage amendments had any adverse or beneficial effects on tomato seedling growth. When essential oil constituents of Monarda were tested for toxicity against P. myriotylum, thymol and carvacrol inhibited mycelial growth at low and high concentrations (5 and 50 µl, respectively). GC-MS analysis of the herbage used in this study showed concentration of thymol and carvacrol to be variable among varieties. ‘Croftway Pink’ was high in thymol; ‘Sioux’ was approximately equal in thymol, carvacrol, and the sesquiterpene thymoquinone. ‘Mohawk’ had a high concentration of thymoquinone and Rose Geranium had no detectible amounts of thymol, carvacrol, or thymoquinone. Treatments with four of sixteen Monarda varieties were successful in decreasing disease index and increasing survival of ‘Mountain Spring’ seedlings when challenged with the pathogen. ‘Croftway Pink’ dominated the varieties with significantly increased shoot height, stem diameter, and survival, as well as decreased disease index in tomato seedlings. Three other amendments, ‘Sioux’, ‘Mohawk’, and Rose Geranium, had no negative effects on seedling growth and increased seedling survival

Social Differences of Adolescents with High-Functioning Autism and Asperger\u27s Syndrome

This study evaluated the social skills of adolescents with high-functioning autism (HFA), Asperger\u27s syndrome (AS), and neurotypical development (NT). Currently, it is unknown whether there are significant differences in the social skills of individuals in these three groups, especially in the adolescent population. This study employed a group comparative design with 5-10 subjects in each respective group. The Social Language Development Test-Adolescent (SLDT-A) yielded standard scores for quantitative analysis that were analyzed using appropriate inferential statistics. This study found that adolescents with AS performed somewhat better on a standardized measure of social skills than those with HFA. As predicted, neither group with autism spectrum disorders performed as well as subjects with NT development. Therefore, the social skills of adolescents with AS and those with HFA are impaired and in need of remediation. No one area of social skill development was more impaired than another. The results of this project will contribute to our understanding of social skills and behavior of individuals with autism spectrum disorders, and how best to evaluate the social aspect of HFA and AS

Chronic Stress in Relation to Locus of Control

Stress is prominent in everyone’s lives, and if the right precautions are not taken, stress can become chronic and harmful to an individual’s health (Schmitz, Neumann, & Oppermann, 2000). To prevent chronic stress, researchers seek to find out important factors that lead to chronic stress. One of the most prominent factors leading to chronic stress is locus of control (LOC), or how much control people feel they have over situations (Cummins, 1988). People can endorse an internal locus of control which means individual attributes events occurring in their life to their own behavior, or an external, which one would consider an outside force responsible for an event that occurred in their life (Bollini, Walker, Hamann, & Kestler, 2004). There are mixed results in the literature regarding different forms of stress and locus of control. Some results indicate that external locus of control is related to higher stress levels (Schmitz et al. 2000), some results indicate that a more internal locus of control is related to higher stress (Cummins, 1988), while others found no significant relationship (Bollini et al. 2004). For this experiment, researchers wanted to examine the relationship between type of locus of control and amount of chronic stress. It was predicted that greater external locus of control would be associated with increased chronic stress. In the present study, UMSL students (n=81) completed the Life Stressors Checklist to measure amount of stress exposure, as well as the Locus of Control Scale to measure if participants had more internal or external locus of control. We found that LOC was not correlated with levels of chronic stress (F(1,79)=0.049, p\u3e0.05). Although a significant relationship was not found, it is still important that individuals learn to manage stress, because stress presents itself similarly, no matter which perception of control an individual possesses (Bollini et al. 2004)

Local solutions for a hyperbolic equation

Let $\Omega$ be an open bounded set of $\mathbb{R}^n$ with its boundary $\Gamma$ constituted of two disjoint parts $\Gamma_0$ and $\Gamma_1$ with $\overline{\Gamma}_0 \cap \overline{\Gamma}_1=\emptyset.$ This paper deals with the existence of local solutions to the nonlinear hyperbolic problem \begin{equation} \left| \begin{aligned} &u'' - \triangle u + |u|^\rho=f &\quad& \mbox{in} \ \Omega \times (0, T_0), \\ &u=0 &\quad&\mbox{on} \ \Gamma_0 \times (0, T_0), \\ & \displaystyle\frac{\partial u}{\partial \nu} + h(\cdot,u')=0 &\quad&\mbox{on} \ \Gamma_1 \times (0, T_0), \end{aligned} \right. \tag{$\ast$} \end{equation} where $\rho >1$ is a real number, $\nu(x)$ is the exterior unit normal at $x\in \Gamma_1$ and $h(x,s)$ (for $x \in \Gamma_1$ and $s \in \mathbb{R}$) is a continuous function and strongly monotone in $s$. We obtain existence results to problem ($\ast$) by applying the Galerkin method with a special basis, Strauss' approximations of continuous functions and trace theorems for non-smooth functions. As usual, restrictions on $\rho$ are considered in order to have the continuous embedding of Sobolev spaces

Mechanical Differences Between Sexes During A Jump Landing

Jump landings are a frequent occurrence in both male and female sports. However, aberrant landing mechanics, such as landing with smaller knee flexion angles (KFA), can increase the likelihood of knee joint injury. Previous research suggests males and females demonstrate different landing mechanics, which could explain the higher incidence of knee injuries in females, such as anterior cruciate ligament (ACL) injury. PURPOSE: The purpose of this study was to compare lower extremity landing biomechanics associated with ACL injury between males and females. We hypothesized that females would land with smaller KFA and greater knee abduction angles (KAA) compared to males. METHODS: Landing biomechanics were assessed in 15 males (23.46±2.75 yrs, 1.77±0.06 m, 77.81±14.01kg) and 15 females (21.24±1.99 yrs, 1.63±0.06 m, 63.15±12.19kg) during a jump landing task. All participants had experience playing sports that required jumping and landing. Separate independent samples t-tests were used to compare KFA at initial contact, knee abduction angle (KAA) at initial contact, peak KFA, and peak KAA between males and females. RESULTS: Males demonstrated larger KFA at initial contact compared to females (16.52±4.55o vs 12.85±4.91o, p=0.04), but smaller KAA at initial contact (3.13±2.07o vs 0.93±052o, po vs 91.88±10.71o, p=0.03) and smaller peak KAA (-2.97±2.0o vs -6.49±4.11o, p=0.004). CONCLUSION: The landing mechanics demonstrated by females may be problematic, as smaller KFA when landing have been associated with higher forces being absorbed, increasing the odds of ACL injury. Furthermore, females also demonstrated greater KAA, which have also been linked with traumatic knee injury. Therefore, females participating in sports involving landing from a jump could benefit from interventions that aim to improve landing kinematics

Resonant gravity-wave drag enhancement in linear stratified flow over mountains

High-drag states produced in stratified flow over a 2D ridge and an axisymmetric mountain are investigated using a linear, hydrostatic, analytical model. A wind profile is assumed where the background velocity is constant up to a height z1 and then decreases linearly, and the internal gravity-wave solutions are calculated exactly. In flow over a 2D ridge, the normalized surface drag is given by a closed-form analytical expression, while in flow over an axisymmetric mountain it is given by an expression involving a simple 1D integral. The drag is found to depend on two dimensionless parameters: a dimensionless height formed with z_1, and the Richardson number, Ri, in the shear layer. The drag oscillates as z_1 increases, with a period of half the hydrostatic vertical wavelength of the gravity waves. The amplitude of this modulation increases as Ri decreases. This behaviour is due to wave reflection at z_1. Drag maxima correspond to constructive interference of the upward- and downward-propagating waves in the region z < z_1, while drag minima correspond to destructive interference. The reflection coefficient at the interface z = z_1 increases as Ri decreases. The critical level, z_c, plays no role in the drag amplification. A preliminary numerical treatment of nonlinear effects is presented, where z_c appears to become more relevant, and flow over a 2D ridge qualitatively changes its character. But these effects, and their connection with linear theory, still need to be better understood

The Effects Of A Heel Lift On Squat Biomechanics

The barbell squat is an effective exercise for improving lower extremity function. During the descent of a squat, the hip and knee joints flex while the ankle joint dorsiflexes. The hip and knee joints then extend and the ankle joint plantarflexes when standing up. During the squat, some athletes use shoes with an elevated heel or other means of heel elevation to achieve lower squat depth. Research has suggested that use of heel elevation may improve range of motion (ROM) of the lower extremity joints and improve stability of the movement during deep squats, especially with an external load. PURPOSE: The purpose of this study was to compare lower extremity biomechanics during the back squat exercise in a heel-lift (HL) vs non-heel lift (NHL) condition. We hypothesized that the HL condition would result in greater peak knee flexion angles (KFA) and greater net knee joint moments (NJM). METHODS: 25 healthy participants (13 male, 12 female, 23.6±3.14 yrs., 1.70±0.08 m, 72.24±12.86kg) who had back squatted at least once per week for the last three months were recruited for data collection. 2 visits were required from each participant with the first visit involving back squat one-repetition-maximum (1RM) testing (101.62±41.40kg). During the second visit, participants underwent 3-D biomechanical analyses for the back squat with and without heel lift. Participants performed three repetitions at 75% 1RM for each condition in a randomized order, with a five-minute rest period. Squat velocity was controlled for by using a metronome set to 20 beats per minute. The 2nd of the three repetitions was used for analysis. Paired samples T-tests were used to compare peak knee NJM and peak KFA between the HL and NHL conditions. RESULTS: No differences were found between HL and NHL for knee NJM (2.79±0.96 Nm/kg-1vs 2.7±0.79 Nm/kg-1, p=0.72) or peak KFA (126.03±15.73o vs 125.8±15.39o, p=0.83) CONCLUSION: Results contradict our hypothesis, as the HL did not increase the participants KFA or knee NJM. These results suggest that shoe type used during the back squat exercise may be left up to user preference as to what is comfortable for them. Future studies may aim to see if adding a HL influences lower extremity biomechanics when the load is closer to 1RM, or in other squat variations