1,938 research outputs found
Can children resist making interpretations when uncertain?
In two experiments we examined young children’s ability to delay a response to ambiguous input. In Experiment 1 5- and 6- year olds performed as poorly when they had to choose between basing an interpretation on ambiguous input and delaying an interpretation as when making explicit evaluations of knowledge. Seven- and 8- year olds’ found the former task easy. In Experiment 2 5- and 6- year olds performed well on a task that required delaying a response but removed the need to decide between strategies.
We discuss children’s difficulty with ambiguity in terms of the decision making demands made by different procedures. These demands appear to cause particular problems for
young children
The effect of a shallow low viscosity zone on mantle convection and its expression at the surface of the earth
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 1987Many features of the oceanic plates cannot be explained
by conductive cooling with age. A number of these anomalies
require additional convective thermal sources at depths
below the plate: mid-plate swells, the evolution of fracture
zones, the mean depth and heat flow relationships with age
and the observation of small scale (150-250 km) geoid and
topography anomalies in the Central Pacific and Indian
oceans. Convective models are presented of the formation
and evolution of these features. In particular, the effect
of a shallow low viscosity layer in the uppermost mantle on
mantle flow and its geoid, topography, gravity and heat flow
expression is explored. A simple numerical model is
employed of convection in a fluid which has a low viscosity
layer lying between a rigid bed and a constant viscosity
region. Finite element calculations have been used to
determine the effects of (1) the viscosity contrast between
the two fluid layers, (2) the thickness of the low viscosity
zone, (3) the thickness of the conducting lid, and (4) the
Rayleigh number of the fluid based on the viscosity of the
lower layer.
A model simple for mid-plate swells is that they are
the surface expression of a convection cell driven by a heat
flux from below. The low viscosity zone causes the top
boundary layer of the convection cell to thin and, at high
viscosity contrasts and Rayleigh numbers, it can cause the
boundary layer to go unstable. The low viscosity zone also
mitigates the transmission of normal stress to the
conducting lid so that the topography and geoid anomalies
decrease. The geoid anomaly decreases faster than the
topography anomaly, however, so that the depth of
compensation can appear to be well within the conducting
lid. Because the boundary layer is thinned, the elastic
plate thickness also decreases and, since the low viscosity
allows the fluid to flow faster in the top layer, the uplift
time decreases. as well. We have compared the results of
this modeling to data at the Hawaii, Bermuda, Cape Verde and
Marquesas swells, and have found that it can reproduce their
observed anomalies. The viscosity contrasts that are
required range from 0.2-0.01, which are in agreement with
other estimates of shallow viscosity variation in the upper
mantle. Also, the estimated viscosity contrast decreases as
the age of the swell increases. This trend is consistent
with theoretical estimates of the variation of such a low
viscosity zone with age.
Fracture zones juxtapose segments of the oceanic plates
of different ages and thermal structures. The flow induced
by the horizontal temperature gradient at the fracture zone
initially downwells immediately adjacent to the fracture
zone on the older side, generating cells on either side of
the plume. The time scale and characteristic wavelength of
this flow depends initially on the viscosity near the
largest temperature gradient in the fluid which, in our
model, is the viscosity of the low viscosity layer. They
therefore depend on .both the Rayleigh number and the
viscosity contrast between the layers. Eventually the flow
extends throughout the box, and the time scales and the
characteristic wavelengths of the flow depend on the
thickness and viscosity of both layers. When the Rayleigh
number based on the viscosity of the top later, and the
depth of both fluid layers, is less than 106 , the geoid
anomalies of these flows are dominated by the convective
signal. When this Rayleigh number exceeds 106, the geoid
anomalies retain a step across the fracture zone out to
large ages. We have compared our results to geoid anomalies
over the Udintsev fracture zone, and have found that the
predicted geoid anomalies, with high effective Rayleigh
numbers, agree at longer wavelengths with the observed
anomalies and can produce the observed geoid slope-age
behaviour. We have also compared the calculated topographic
steps to those predicted by the average depth-age
relationships observed in the oceans. We have found that
only with a low viscosity zone will the flow due to fracture
zones not disturb the average depth versus age
relationships.
We have also applied the model to a numerical study of
the effect of a low viscosity zone in the uppermost mantle
on the onset and surface expression of convective
instabilities in the cooling oceanic plates. We find that
the onset and magnitude of the geoid, topography and heat
flow anomalies produced by these instabilities are very
sensitive to the viscosity contrast and the Rayleigh number,
and that the thickness of the low viscosity zone is
constrained by the wavelength of the observables. If the
Rayleigh number of the low viscosity zone exceeds a critical
value then the convection will be confined to the low
viscosity zone for a period which depends on the viscosity
contrast and the Rayleigh number. The small scale
convection will eventually decay into longer wavelength
convection which extends throughout the upper mantle, so
that the small scale convective signal will eventually be
succeeded by a longer wavelength signal. We compare our
model to the small scale geoid and topography anomalies
observed in the Southeast Pacific. The magnitude (0.50-0.80
m in geoid and 250 m in topography), early onset time (5-10
m.y.) and lifetime (over 40 m.y.) of these anomalies suggest
a large viscosity contrast of greater than two orders of
magnitude. The trend to longer wavelengths also suggests a
high Rayleigh number of near or over 10 and their original
150-250 km wavelength indicates a low viscosity zone of 75-125
km thickness. We have found that the presence of such
small scale convection does not disturb the slope of the
depth-age curve but elevates it by up to 250 m, and it is
not until the onset of long wavelength convection that the
depth-age curves radically depart from a cooling halfspace
model. In the Pacific, the depth-age curve is slightly
elevated in the region where small scale convection is
observed and it does not depart from a halfspace cooling
model until an age of 70 m.y.. Models that produce the
small scale anomalies predict a departure time between 55
and 65 m.y.. These calculations also predict an asymptotic
heat flow on old ocean floor which is higher than the plate
model and between 50 and 55 mW/m2. This value agrees with
measurements of heat flow on old seafloor in the Atlantic.
In conclusion, we prefer an approximate model for the
viscosity structure of the upper mantle which initially has
a 125 km thick low viscosity zone that represents a
viscosity contrast of two orders of magnitude. The
viscosity contrast decreases as the plate ages to one order
of magnitude or less by 130 m.y., and the. low viscosity zone
may also thicken with age. Finally, the Rayleigh number of
the upper mantle is at least 105 and may be as large as 107.
With this model, the evolution of the surface plates would
initially involve small scale convection which is driven by
shear coupling to instabilities downstream and to small
scale convection associated with fracture zones. This
convective flow would begin at close to 5 m.y. and remain
confined to the low viscosity zone until nearly 40 m.y.. As
this convective flow cools the upper mantle beneath the low
viscosity zone, longer wavelength convection begins
throughout the upper (or whole) mantle, and the heat
transport from the longer wavelength convection flattens the
depth-age curve and may form swells
The Contribution of Parent Psychosocial Functioning to Parental Monitoring, Youth Adherence, and Glycemic Control during Adolescence
Objective: Type 1 diabetes is one of the most common pediatric chronic illnesses. Adolescents are at risk for poorer adherence and in turn, poorer glycemic control; however, youth whose parents remain involved in diabetes care are in better control. A parent’s level of involvement is dependent in part upon his or her own social and emotional functioning. Much is known about the link between separate aspects of parent psychosocial functioning (e.g., depressive symptoms, parental stress) and parent involvement in diabetes care, adherence, and glycemic control. However, no study to our knowledge has examined these constructs simultaneously as they interrelate to one another and to youth diabetes status. Given the complexity of human behavior, use of multiple indicators of parent psychosocial status should provide a comprehensive portrayal of precursors to parental monitoring. Methods: The current study used structural equation modeling (SEM) in a sample of 257 parent-youth (aged 11-14) dyads (91% mothers) to examine comprehensive parent psychosocial functioning including parental distress, authoritative parenting, and parental self-efficacy for diabetes management as related to parental monitoring, youth adherence and glycemic control. Results: The SEM model fit the data well [χ2 (121) = 209.24, p \u3c .001, CFI = .93, TLI = .91, RMSEA = .06, SRMR = .08]. Overall, the model accounted for 30% of the variance in parental monitoring, 27% of the variance in adherence, and 22% of the variance in glycemic control. Specifically, lower levels of parental distress (i.e., depressive symptoms, parenting stress, and hypoglycemic fear) related to higher parental self-efficacy for diabetes management and more authoritative parenting, each of which in turn related to more parental monitoring. Further, higher parental self-efficacy related directly to better youth adherence. Conclusions: The current study shows interrelated paths of parent psychosocial functioning associated with parental monitoring of youth diabetes care and ultimately, youth adherence and glycemic control. Interventions that target diabetes adherence in adolescents with T1D should consider screening for and treatment of parental distress
The effects of oil on blue crab and periwinkle snail interactions: A mesocosm study
We examined the sub-lethal effect of Macondo oil from the Deepwater Horizon oil spill on predator-prey interactions using blue crabs (Callinectes sapidus) and periwinkle snails (Littoraria irrorata). A 2 x 2 factorial mesocosm design determined the effect of oil (no oil vs. oil) and blue crabs (no blue crab predator vs. one blue crab predator) on periwinkle snail climbing and survival. Sixteen mesocosm tanks were used in the experiment, which were replicated three times. Each tank contained water, sand, and Spartina marsh stems. The sixteen tanks were divided between two, temperature-controlled chambers to separate oil treatments (no oil vs. oil). Oil was buried in the sand to prevent direct coating of mesocosm organisms. Half of the tanks contained only snails, while the other half contained snails and (one) blue crab in each chamber. Snail climbing behavior and survival were documented every 12 h over 96 h. Snails exposed to oil without a blue crab predator survived as well as snails not exposed to oil and no blue crab predator. Oil reduced snail survival in the presence of a blue crab predator. The increase in snail mortality can be attributed to changes in snail climbing behavior. Oil significantly reduced snail climbing height in the presence and absence of a blue crab predator. This change in behavior and subsequent decrease in snail survival could be beneficial for Spartina during recovery after an oil spill. A decrease in snail populations would reduce grazing stress on Spartina. However, field research immediately after an oil spill would be more useful in determining predator-prey interactions and further food web effects
Effects of Black Mangrove (Avicennia germinans) Expansion on Saltmarsh (Spartina alterniflora) Benthic Communities of the South Texas Coast
This study examined the effects of mangrove expansion on benthic communities. This was accomplished by examining plant composition, benthic community composition, and belowground root biomass. Two sites were examined: Corpus Christi Pass, Corpus Christi, TX where mangroves have become more common in the last decade and the Lower Laguna Madre, South Padre Island, TX where mangroves are well established. This research seeks to provide preliminary results to provide direction for future studies examining the interplay of S. alterniflora and A. germinans habitat on benthic communities. We hypothesize that the more established site of South Padre Island will have greater numbers of species than the newer communities of Corpus Christi, and that A. germinans habitats will have lower diversity of infaunal organisms than S. alterniflora habitats
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The impact of buffer zone size and management on illegal extraction, park protection and enforcement
Many protected areas or parks in developing countries have buffer zones at their boundaries to achieve the dual goals of protecting park resources and providing resource benefits to neighbouring people. Despite the prevalence of these zoning policies, few behavioural models of people’s buffer zone use inform the sizing and management of those zones. This paper uses a spatially explicit resource extraction model to examine the impact of buffer zone size and management on extraction by local people, both legal and illegal, and the impact of that extraction on forest quality in the park’s core and buffer zone. The results demonstrate trade-offs between the level of enforcement, the size of a buffer zone, and the amount of illegal extraction in the park; and describe implications for “enrichment” of buffer zones and evaluating
patterns of forest degradation
Paving Pathways: shaping the Public Health workforce through tertiary education
Public health educational pathways in Australia have traditionally been the province of Universities, with the Master of Public Health (MPH) recognised as the flagship professional entry program. Public health education also occurs within the fellowship training of the Faculty of Public Health Medicine, but within Australia this remains confined to medical graduates. In recent years, however, we have seen a proliferation of undergraduate degrees as well as an increasing public health presence in the Vocational Education and Training (VET) sector.
Following the 2007 Australian Federal election, the new Labour government brought with it a refreshing commitment to a more inclusive and strategic style of government. An important example of this was the 2020 visioning process that identified key issues of public health concern, including an acknowledgment that it was unacceptable to allocate less than 2% of the health budget towards disease prevention. This led to the recommendation for the establishment of a national preventive health agency (Australia: the healthiest country by 2020 National Preventative Health Strategy, Prepared by the Preventative Health Taskforce 2009).
The focus on disease prevention places a spotlight on the workforce that will be required to deliver the new investment in health prevention, and also on the role of public health education in developing and upskilling the workforce. It is therefore timely to reflect on trends, challenges and opportunities from a tertiary sector perspective. Is it more desirable to focus education efforts on selected lead issues such as the "obesity epidemic", climate change, Indigenous health and so on, or on the underlying theory and skills that build a flexible workforce capable of responding to a range of health challenges? Or should we aspire to both?
This paper presents some of the key discussion points from 2008 - 2009 of the Public Health Educational Pathways workshops and working group of the Australian Network of Public Health Institutions. We highlight some of the competing tensions in public health tertiary education, their impact on public health training programs, and the educational pathways that are needed to grow, shape and prepare the public health workforce for future challenges
ASSESSING PARENTAL INVOLVEMENT IN TYPE 1 DIABETES MANAGEMENT DURING ADOLESCENCE
Type 1 diabetes is one of the most common pediatric chronic illnesses. Adolescents are at risk for poorer glycemic control; however, youth whose parents remain involved in diabetes care are in better control. The current study examined parental involvement (PI) using a multi-method, multi-source approach in a sample of 255 youth (Age M = 12.83). The Diabetes Family Responsibility Questionnaire, Parental Monitoring of Diabetes Care Scale, and 24-Hour Diabetes Interview assessed two types of PI, parental responsibility and parental monitoring. Global and specific assessment served to cross-corroborate indicators of PI related to HbA1c. Higher levels of monitoring related to lower HbA1c for both parent- and youth-report; however, the effect decreased after controlling for socioeconomic status (SES). Additionally, monitoring mediated the relation between age and HbA1c. Controlling for SES, youth whose parents demonstrated higher levels of monitoring were in better glycemic control. Both research and clinical implications are discussed
Paving Pathways: shaping the Public Health workforce through tertiary education
Public health educational pathways in Australia have traditionally been the province of Universities, with the Master of Public Health (MPH) recognised as the flagship professional entry program. Public health education also occurs within the fellowship training of the Faculty of Public Health Medicine, but within Australia this remains confined to medical graduates. In recent years, however, we have seen a proliferation of undergraduate degrees as well as an increasing public health presence in the Vocational Education and Training (VET) sector
What children know about the source of their knowledge without reporting it as the source
We argue that, amongst 3- to 5- year-olds, failure to report the source of knowledge recently acquired in answer to “How do you know…?” is due to a specific failure to make a causal inference, in line with source monitoring theory but not fuzzy trace theory. In three Experiments, children (N = 37; 30; 59) identified a hidden toy by seeing, feeling, or by being told, having had two modes of access on each trial, one informative (e.g. seeing a toy identified by colour) and the other uninformative (e.g. being told the toy’s colour by the Experimenter who had only felt it). Children who answered the know question wrongly nevertheless reported accurately who saw and who felt the toy, and what the well-informed player had said. They also realised when
the Experimenter’s uninformative access implied their own knowledge was unreliable, suggesting precocious working understanding of knowledge sources
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