196 research outputs found
15 years of VLT/UVES OH intensities and temperatures in comparison with TIMED/SABER data
The high-resolution echelle spectrograph UVES of the Very Large Telescope at
Cerro Paranal in Chile has been regularly operated since April 2000. Thus, UVES
archival data originally taken for astronomical projects but also including sky
emission can be used to study airglow variations on a time scale longer than a
solar cycle. Focusing on OH emission and observations until March 2015, we
considered about 3,000 high-quality spectra from two instrumental set-ups
centred on 760 and 860 nm, which cover about 380 nm each. These data allowed us
to measure line intensities for several OH bands in order to derive band
intensities and rotational temperatures for different upper vibrational levels
as a function of solar activity and observing date. The results were compared
with those derived from emission and temperature profile data of the radiometer
SABER on the TIMED satellite taken in the Cerro Paranal area between 2002 and
2015. In agreement with the SABER data, the long-term variations in OH
intensity and temperature derived from the UVES data are dominated by the solar
cycle, whereas secular trends appear to be negligible. Combining the UVES and
SABER results, the solar cycle effects for the OH intensity and temperature are
about 12 to 17% and 4 to 5 K per 100 sfu and do not significantly depend on the
selected OH band. The data also reveal that variations of the effective OH
emission layer height and air density can cause significant changes in the OH
rotational temperatures due to a varying ratio of OH thermalising collisions by
air molecules and OH radiation, deactivation, and destruction processes which
impede the rotational relaxation. However, this effect appears to be of minor
importance for the explanation of the rotational temperature variations related
to the solar activity cycle, which causes only small changes in the OH emission
profile.Comment: preprint with 22 pages and 11 figures, accepted for publication in
JAST
Out With the Old, In With the New: Are Western Commodity Producers Ready for Buyouts?
Agricultural and Food Policy,
Risk Management for Ag Families: An Extension Model for Improving Family Business Success
A risky business environment for agricultural producers coupled with human risk elements unique to family businesses, points to the need for extension programs that integrate traditional risk management concepts into curriculums focused on the potentially unique educational needs of family farm management teams. Results in this paper indicate that a multi-state, grant funded program entitled "Risk Management for Ag Families" had impact and provides a model that traditional risk management education programs could benefit from.Risk and Uncertainty, Teaching/Communication/Extension/Profession,
Walking dynamics are symmetric (enough)
Many biological phenomena such as locomotion, circadian cycles, and breathing
are rhythmic in nature and can be modeled as rhythmic dynamical systems.
Dynamical systems modeling often involves neglecting certain characteristics of
a physical system as a modeling convenience. For example, human locomotion is
frequently treated as symmetric about the sagittal plane. In this work, we test
this assumption by examining human walking dynamics around the steady-state
(limit-cycle). Here we adapt statistical cross validation in order to examine
whether there are statistically significant asymmetries, and even if so, test
the consequences of assuming bilateral symmetry anyway. Indeed, we identify
significant asymmetries in the dynamics of human walking, but nevertheless show
that ignoring these asymmetries results in a more consistent and predictive
model. In general, neglecting evident characteristics of a system can be more
than a modeling convenience---it can produce a better model.Comment: Draft submitted to Journal of the Royal Society Interfac
Is Agricultural Policy Decoupling against Human Nature? Experimental Evidence of Fairness Expectations’ Contributions to Payment Incidence
The objective of this research is to measure individuals’ fairness expectations and relate them to their market behavior in a private-negotiation institution. By doing this, we may inform model parameterization of field data and increase understanding of payment incidence causation. We hypothesize agents will change both their market and UG behavior when the tenant/proposer receives a subsidy following a successful negotiation. We also hypothesize that agents’ market behavior does relate to their fairness expectations in the UG. Two economic experiments were developed to test our hypotheses, a market and an ultimatum bargaining game experiment. We recruited 106 undergraduate students and conducted the experiments in an experimental laboratory using a computer based market mechanism. Our findings suggest fairness expectations need to be considered as a possible constraint on agents’ profit maximization behavior in land markets. The experimental evidence indicates market sellers or landlords demand higher land rental prices when tenants receive per-unit subsidies. Their ability to obtain a higher price appears to be more formidable in markets with limited matching opportunities. We conclude fairness expectations may constrain individuals’ profit-maximization behavior in the land market and, in turn, affect payment incidence in this market.Agricultural and Food Policy,
Decoupled Programs, Payment Incidence, and Factor Markets: Evidence from Market Experiments
We use laboratory market experiments to assess the impact of asymmetric knowledge of a per-unit subsidy and the effect of a decoupled annual income subsidy on factor market outcomes. Results indicate that when the subsidy is tied to the factor as a per-unit subsidy, regardless of full or asymmetric knowledge for market participants, subsidized factor buyers distribute nearly 22 percent of the subsidy to factor sellers. When the subsidy is fully decoupled from the factor, as is the case with the annual payment, payment incidence is mitigated and prices are not statistically different from the no-policy treatment.laboratory market experiments, agricultural subsidies, subsidy incidence, land market, ex ante policy analysis, Agricultural and Food Policy, Institutional and Behavioral Economics, Q18, D03, C92,
Risk Management for Ag Families: Evaluation of an Integrated Educational Program for Producers on the Northern Plains
This article analyzes the impact of a series of educational programs focusing on risk management for agricultural families structured as a series of short educational sessions coupled with hands-on learning activities. Responses of program participants to pre- and post-workshop questionnaires, series questionnaires, and a follow-up mail survey are analyzed using non-parametric statistics. Results indicate that this integrated format, focusing on areas of risk affecting agricultural family businesses, had a positive impact on knowledge levels and behavior. Overall, these results suggest this type of educational format may have merit as compared to more didactic approaches for delivering risk management education
Ranchers Diverse in Their Drought Management Strategies
Farm Management, Livestock Production/Industries,
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Increasing Motor Noise Impairs Reinforcement Learning in Healthy Individuals.
Motor variability from exploration is crucial for reinforcement learning as it allows the nervous system to find new task solutions. However, motor variability from noise can be detrimental to learning and may underlie slowed reinforcement learning performance observed in individuals with cerebellar damage. Here we examine whether artificially increasing noise in healthy individuals slows reinforcement learning in a manner similar to that seen in patients with cerebellar damage. Participants used binary reinforcement to learn to rotate their reach angle in a series of directions. By comparing task performance between conditions with different levels of added noise, we show that adding a high level of noise-matched to a group of patients with cerebellar damage-slows learning. In additional experiments, we show that the detrimental effect of noise may lie in reinforcing incorrect behavior, rather than not reinforcing correct behavior. By comparing performance between healthy participants with added noise and a group of patients with cerebellar damage, we found that added noise does not slow the learning of the control group to the same degree observed in the patient group. Using a mechanistic model, we show that added noise in the present study matched patients' motor noise and total learning. However, increased exploration in the control group relative to the group with cerebellar damage supports faster learning. Our results suggest that motor noise slows reinforcement learning by impairing the mapping of reward to the correct action and that this may underlie deficits induced by cerebellar damage
Micro-and macro-plastics in marine species from Nordic waters
This report summarises the knowledge on plastics in Nordic marine species. Nordic biota interacts with plastic pollution, through entanglement and ingestion. Ingestion has been found in many seabirds and also in stranded mammals. Ingestion of plastics has been documented in 14 fish species, which many of them are of ecology and commercially importance. Microplastics have also been found in blue mussels and preliminary studies found synthetic fibres in marine worms. Comparability between and within studies of plastic ingestion by biota from the Nordic environment and other regions are difficult as there are: few studies and different methods are used. It is important that research is directed towards the knowledge gaps highlighted in this report, to get a better understanding on plastic ingestion and impact on biota from the Nordic marine environment
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