Roots-eye view: using microdialysis and microCT to non-destructively map root nutrient depletion and accumulation zones

Improvement in fertiliser use efficiency is a key aspect for achieving sustainable agriculture in order to minimise costs, greenhouse gas emissions and pollution from nutrient runoff. To optimise root architecture for nutrient uptake and efficiency we need to understand what the roots encounter in their environment. Traditional methods of nutrient sampling such as salt extractions can only be done at the end of an experiment, are impractical for sampling locations precisely and give total nutrient values which can overestimate the nutrients available to the roots. In contrast, microdialysis provides a non-invasive, continuous method for sampling available nutrients in the soil. Here for the first time we have used microCT imaging to position microdialysis probes at known distances from the roots and then measured the available nitrate and ammonium. We found that nitrate accumulated close to roots while ammonium was depleted demonstrating that this combination of complementary techniques provides a unique ability to measure root-available nutrients non-destructively and in almost real-time

Vasopressin-dependent flank marking in golden hamsters is suppressed by drugs used in the treatment of obsessive-compulsive disorder

BACKGROUND: Alterations in arginine vasopressin regulation and secretion have been proposed as one possible biochemical abnormality in patients with obsessive-compulsive disorder. In golden hamsters, arginine vasopressin microinjections into the anterior hypothalamus trigger robust grooming and flank marking, a stereotyped scent marking behaviors. The intensity and repetition of the behaviors induced by arginine vasopressin is somewhat reminiscent of Obsessive Compulsive Disorder in humans. The present experiments were carried out to test whether pharmacological agents used to alleviate obsessive compulsive disorder could inhibit arginine vasopressin-induced flank marking and grooming. RESULTS: Male golden hamsters were treated daily for two weeks with either vehicle, fluoxetine, clomipramine, or desipramine (an ineffective drug), before being tested for arginine vasopressin-induced flank marking and grooming. Flank marking was significantly inhibited in animals treated with fluoxetine or clomipramine but unaffected by treatment with desipramine. Grooming behavior was not affected by any treatment. CONCLUSION: These data suggest that arginine vasopressin-induced flank marking may serve as an animal model for screening drugs used in the control of Obsessive Compulsive Disorder

Signature of Obliquity and Eccentricity in Soil Chronosequences

Periodic shifts in Earth\u27s orbit alter incoming solar radiation and drive Quaternary climate cycles. However, unambiguous detection of these orbitally driven climatic changes in records of terrestrial sedimentation and pedogenesis remains poorly defined, limiting our understanding of climate change‐landscape feedbacks, impairing our interpretation of terrestrial paleoclimate proxies, and limiting linkages among pedogenesis, sedimentation, and paleoclimatic change. Using a meta‐analysis, we show that Quaternary soil ages preserved in the modern record have periodicities of 41 and 98 kyr, consistent with orbital cycles. Further, soil ages predominantly date to periods of low rates of climatic change following rapid climate shifts associated with glacial‐to‐interglacial transitions. Soil age appears linked to orbital cycles via climate‐modulated sediment deposition, which may largely constrain soil formation to distinct climate periods. These data demonstrate a record of widespread orbital cyclicity in sediment deposition and subsequent pedogenesis, providing a key insight into soil‐landscape evolution and terrestrial paleo‐environment changes

A Program for Education in Certification and Accreditation

Large complex systems need to be analyzed prior to operation so that those depending upon them for the protection of their information have a well defined understanding of the measures that have been taken to achieve security and the residual risk the system owner assumes during its operation. The U.S. military calls this analysis and vetting process certification and accreditation. Today there is a large, unsatisfied need for personnel qualified to conduct system certifications. An educational program to address those needs is described. Large complex systems need to be analyzed prior to operation so that those depending upon them for the protection of their information have a well defined understanding of the measures that have been taken to achieve security and the residual risk the system owner assumes during its operation. The U.S. military calls this analysis and vetting process certification and accreditation. Today there is a large, unsatisfied need for personnel qualified to conduct system certifications. An educational program to address those needs is described.Approved for public release; distribution is unlimited

MA (Applied Mathematics) Annual Departmental Awards

2013 Department of Applied Mathematics Faculty AwardsThis year’s recipients are hereby appointed as the committee in charge of the departmental awards for the next cycle with Prof. Rasmussen (the most senior member) as committee chair.2013 Department of Applied Mathematics Faculty Annual Department Awards were awarded in three areas: instruction, research and service. Following custom, this yearﾒs recipients will constitute the 2014 Award Committee. This committee will be chaired by Professor Beny Neta, in honor of his seniority among this yearﾒs recipients

Soil minerals mediate climatic control of soil C cycling on annual to centennial timescales

Climate and parent material both affect soil C persistence, yet the relative importance of climatic versus mineralogical controls on soil C dynamics remains unclear. To test this, we collected soil samples in 2001, 2009, and 2019 along a combined gradient of parent material (andesite, basalt, granite) and climate (mean annual temperature (MAT): 6.5 &deg;C &ldquo;cold&rdquo;, 8.6 &deg;C &ldquo;cool&rdquo;, 12.0 &deg;C &ldquo;warm&rdquo;). We measured the radiocarbon of heterotrophically respired CO2 (∆14Crespired) and bulk soil C (∆14Cbulk) as proxies for transient and persistent soil C, and characterized mineral assemblages using selective dissolution. Using linear regression, we observed that MAT was not a significant predictor of either ∆14Cbulk or ∆14Crespired, yet climate was highly significant as a categorical variable. Climate explained more variance in ∆14Cbulk and ∆14Crespired over 0&ndash;0.1 m, but parent material explained more from 0.1&ndash;0.3 m. Cool site soil C was more persistent (lower ∆14Cbulk) than cold or warm climate sites, and also more persistent on andesitic soils, followed by basaltic and then granitic soils. Poorly crystalline metal oxides (PCMs) (but not crystalline metal oxides) were significantly (p &lt; 0.1) correlated with ∆14Cbulk, ∆14Crespired, and ∆14Crespired - ∆14Cbulk, indicating their importance for soil C cycling on both short and long timescales. The change in ∆14Crespired observed over the study period was linearly related to MAT for the granite soils with the lowest PCM content, but not in the andesitic and basaltic soils with higher PCM content. This link between PCM abundance and the decoupling of MAT and soil C cycling rates suggests PCMs may attenuate the temperature sensitivity of decomposition.</p

A comparison of statistical emulation methodologies for multi-wave calibration of environmental models

Expensive computer codes, particularly those used simulating environmental or geological processes such as climate models, require calibration (sometimes called tuning). When calibrating expensive simulators using uncertainty quantification methods, it is usually necessary to use a statistical model called an emulator in place of the computer code when running the calibration algorithm. Though emulators based on Gaussian processes are typically many orders of magnitude faster to evaluate than the simulator they mimic, many applications have sought to speed up the computations by using regression-only emulators within the calculations instead, arguing that the extra sophistication brought using the Gaussian process is not worth the extra computational power. This was the case for the analysis that produced the UK climate projections in 2009. In this paper we compare the effectiveness of both emulation approaches upon a multi-wave calibration framework that is becoming popular in the climate modelling community called \history matching". We find that Gaussian processes offer significant benefits to the reduction of parametric uncertainty over regression-only approaches. We find that in a multi-wave experiment, a combination of regression-only emulators initially, followed by Gaussian process emulators for refocussing experiments can be nearly as effective as using Gaussian processes throughout for a fraction of the computational cost. We also discover a number of design and emulator-dependent features of the multi-wave history matching approach that can cause apparent, yet premature, convergence of our estimates of parametric uncertainty. We compare these approaches to calibration in idealised examples and apply it to a well-known geological reservoir mode

A two-dimensional model of the plasmasphere: refilling time constants

A two-dimensional model of the plasmasphere has been developed to study the temporal evolution of plasma density in the equatorial plane of the magnetosphere. This model includes the supply and loss of hydrogen ions due to ionosphere-magneto-sphere coupling as well as the effects of E x B convection. A parametric model describing the required coupling fluxes has been developed which utilizes empirical models of the neutral atmosphere, the ionosphere and the saturated plasmasphere. The plasmaspheric model has been used to examine the time it takes for the plasmasphere to refill after it has been depleted by a magnetic storm. The time it takes for the plasmasphere to reach 90% of its equilibrium level ranges from 3 days at L = 3 during solar minimum to as high as 100 days at L = 5 during solar maximum. Refilling is also dependent on the month of the year, with refilling requiring a longer period of time at solar maximum during June than during December for L &gt; 3.2.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31025/1/0000702.pd