Irrigation in pine nurseries

This review provides information and opinions about irrigation practices in pine nurseries. Even when nurseries receive more than 15 mm of rainfall week-1, managers irrigate seedbeds to increase germination, increase seed efficiency, and increase root growth. In the southern United States, a 7-month old pine seedling in an outdoor nursery typically receives 2 to 6 kg of water supplied from either sprinklers (39 nurseries) or center-pivot irrigation (12 nurseries). Most nursery managers do not intentionally subject the crop to moisture stress, since most reforestation sites receive adequate rainfall, and many studies show that reducing root mass does not increase seedling performance. In fact, nursery profits can be reduced by more than $13,000 ha-1 when deficit irrigation reduces average seedling diameter by 1 mm. Although some researchers believe that failure to properly drought stress pine seedlings might increase outplanting mortality by up to 75%, research over the past 40 years does not support that myth. When pine seedlings average 5 mm (at the root-collar), water stress is not a reliable method of increasing tolerance to an October freeze event. In several greenhouse trials, researchers grew and tested seedlings that nursery managers would classify as culls (i.e., dry root mass < 0.5 g). Unfortunately, it is common for researchers to make irrigation recommendations without first developing a water-production function curve

Essays in Optimizing Social Policy for Different Populations: Education, Targeting, and Impact Evaluation

In the first chapter of this dissertation, I look at the relationship between preference sets among students in similar majors, compared with different majors, in Peru. I find that students within majors share preference sets that differ from students in other majors. I further find that students from households without a formal labor market participant have made decisions that are more consistent with predicted professional opportunities compared with students with a formal labor market participant. These differences are systematic and not related to the general industrialization level of the city where the student lives. This research suggests that the difference between students and workers from households with formal labor-market familiarity and those from households without formal labor-market familiarity are not accidental or due to lack of familiarity. In the second chapter, I evaluate whether proxy-means testing as a method of targeting for Mexico's Conditional Cash Transfer program caused spending distortions among (potential) recipients. The income and wealth effect of participating in Progresa complicate a simple comparison of members of the control and treatment group in the acquisition of assets. To resolve this, I look at reduced asset acquisition just above the cutoff point. Because an imperfect implementation of the eligibility evaluation may have reduced treatment villagers’ perceived benefit of distorting, I also look for evidence of increased spending in non-assets and of increasing the number of eligible-aged children in the home to increase the size of the transfer. I do not find evidence of lack of investment in assets along the eligibility cutoff, but I do find evidence of increased spending as a percentage of income on items not included in the PMT, as well as evidence of increases in eligible-aged children among the poorest families in treatment villages. In the final chapter, which is joint with Lant Pritchett, we propose that many development programs, projects and policies are characterized by a high dimensional design space with a rugged fitness function over that space. In nearly any project/program/policy there are many design elements, and each design element has a number of possible choices, and the combination produces a high dimensionality design space. If different program designs produce large changes to outcomes/impact, this implies that the "fitness function" or "response surface," the mapping from program design to outcomes/impact, is rugged. We motivate this investigation using as an example a skill-set signaling program for new entrants to the labor market in Peru. We present a simulation model which compares two alternative learning strategies: "crawling the design space" (CDS) and a standard randomized control trial (RCT) approach. In this artificial world, we demonstrate that with even modest dimensionality of the design space and even modest degrees of ruggedness, the CDS learning strategy substantially outperforms the RCT learning strategy. Moreover, we show that the greater the ruggedness of the fitness function, the higher the variance of the RCT results relative to CDS and hence the lower the reliability of RCT results even with "external validity" across contexts. We suggest that RCT results to date are consistent with a world in which social programs exist in a high dimensional design space with rugged fitness functions and hence in which the standard RCT approach has limited direct practical application.Public Polic

Investigating Gaze of Children with ASD in Naturalistic Settings.

BACKGROUND: Visual behavior is known to be atypical in Autism Spectrum Disorders (ASD). Monitor-based eye-tracking studies have measured several of these atypicalities in individuals with Autism. While atypical behaviors are known to be accentuated during natural interactions, few studies have been made on gaze behavior in natural interactions. In this study we focused on i) whether the findings done in laboratory settings are also visible in a naturalistic interaction; ii) whether new atypical elements appear when studying visual behavior across the whole field of view. METHODOLOGY/PRINCIPAL FINDINGS: Ten children with ASD and ten typically developing children participated in a dyadic interaction with an experimenter administering items from the Early Social Communication Scale (ESCS). The children wore a novel head-mounted eye-tracker, measuring gaze direction and presence of faces across the child's field of view. The analysis of gaze episodes to faces revealed that children with ASD looked significantly less and for shorter lapses of time at the experimenter. The analysis of gaze patterns across the child's field of view revealed that children with ASD looked downwards and made more extensive use of their lateral field of view when exploring the environment. CONCLUSIONS/SIGNIFICANCE: The data gathered in naturalistic settings confirm findings previously obtained only in monitor-based studies. Moreover, the study allowed to observe a generalized strategy of lateral gaze in children with ASD when they were looking at the objects in their environment

Sulfur and lime affect soil pH and nutrients in a sandy Pinus taeda nursery

Two pH experiments were conducted at a sandy, bareroot loblolly pine (Pinus taeda L.) nursery in Texas. A sulfur trial (0, 813, 1626, 2439 kg ha-1 of elemental sulfur) was installed to determine if lowering soil pH would result in nutrient toxicity symptoms and affect seedling morphology. Although soil acidity in the sulfur study ranged from pH 3.9 to pH 5.0, none of the treatments resulted in micronutrient toxicity and none affected height growth, root-collar diameter, root mass, shoot mass or the root-mass ratio (root dry mass/total dry mass). Acidifying soil with sulfur increased leaching of calcium, potassium, magnesium, manganese and zinc but there was no effect on seedling morphology. The objective of the liming trial (0, 813, 1626, 3252 kg ha-1 of dolomitic lime) was to determine if increasing alkalinity would result in an iron deficiency and reduce seedling growth. As expected, applying lime increased the calcium and magnesium levels but had no effect on soil levels of iron, phosphorus, potassium, sulfur, zinc and sodium. However, the root-mass ratio was reduced by applications of dolomitic lime (pH ranged from 5.3 to 6.0). Differences in soil properties (i.e. plot location) had a greater effect on seedling morphology than lime applications. Foliage levels of manganese and boron were reduced by the highest rate of lime and sulfur, respectively

Natural killer cells and innate lymphoid cells but not NKT cells are mature in their cytokine production at birth.

Early life is a time of increased susceptibility to infectious diseases and development of allergy. Innate lymphocytes are crucial components of the initiation and regulation of immune responses at mucosal surfaces, but functional differences in innate lymphocytes early in life are not fully described. We aimed to characterise the abundance and function of different innate lymphocyte cell populations in cord blood in comparison to that of adults. Blood was collected from adult donors and umbilical vessels at birth. Multicolour flow cytometry panels were used to identify and characterise lymphocyte populations and their capacity to produce hallmark cytokines. Lymphocytes were more abundant in cord blood compared to adults, however, mucosal-associated invariant T (MAIT) cells and Natural Killer T (NKT)-like cells, were far less abundant. The capacity of NKT-like cells to produce cytokines and their expression of the cytotoxic granule protein granzyme B and the marker of terminal differentiation CD57 were much lower in cord blood than in adults. In contrast, Natural Killer (NK) cells were as abundant in cord blood as in adults, they could produce IFNγ, and their expression of granzyme B was not significantly different to that of adult NK cells, although CD57 expression was lower. All innate lymphoid cell (ILC) subsets were more abundant in cord blood, and ILC1 and ILC2 were capable of production of IFNγ and IL-13, respectively. In conclusion, different innate lymphoid cells differ in both abundance and function in peripheral blood at birth and with important implications for immunity in early life

Building Robota, a Mini-Humanoid Robot for the Rehabilitation of Children with Autism

The Robota project constructs a series of multiple degrees of freedom doll-shaped humanoid robots, whose physical features resemble those of a human baby. The Robota robots have been applied as assistive technologies in behavioral studies with low-functioning children with autism. These studies investigate the potential of using an imitator robot to assess children’s imitation ability and to teach children simple coordinated behaviors. In this paper, we review the recent technological developments that have made the Robota robots suitable for use with children with autism. We critically appraise the main outcomes of two sets of behavioral studies conducted with Robota and discuss how these results inform future development of the Robota robots and generally, robots for the rehabilitation of children with complex developmental disabilities