Iowa State University
  • Ames, IA, United States
Recent publications
Parallel (multi-site) testing tests multiple chips simultaneously, increasing throughput and reducing test costs per chip. As the number of test sites is increased (to further maximize throughput), pronounced variations are often observed in the measurements from site to site, plaguing test accuracy. This paper presents a survey of recent research on detecting and correcting site-to-site variation in analog multi-site testing.
  • Eliska Kloberdanz
    Eliska Kloberdanz
  • Wei Le
    Wei Le
Residual Networks (ResNets) can be interpreted as dynamic systems, which are systems whose state changes over time and can be described with ordinary differential equations (ODEs) [13, 28]. Specifically, the dynamic systems interpretation views individual residual blocks as ODEs. Numerical techniques for solving ODEs result in an approximation; and therefore contain an error term. If an ODE is stiff it is likely that this error is amplified and becomes dominating in the solution calculations, which negatively affects the accuracy of the approximated solution [4]. Therefore, stiff ODEs are often numerically unstable. In this paper we leverage the dynamic systems interpretation to perform a novel theoretical analysis of ResNets by leveraging findings and tools from numerical analysis of ODEs. Specifically, we perform block level stiffness analysis of ResNets. We find that residual blocks towards the end of ResNet models exhibit increased stiffness and that there is a statistically significant correlation between stiffness and model accuracy and loss. Based on these findings, we propose that ResNets behave as stiff numerically unstable ODEs.
Herein, nanostructured Gd-doped ZnFe 2 O 4 (GZFO) has been synthesized via the sol-gel route and its CNT-reinforced nanohybrid was formed via an advanced ultrasonication method. The as-synthesized, hybrid electroactive materials have been supported on aluminum foil (AF) to design a flexible electrode for hybrid capacitor (HC) applications. Nanostructured material synthesis, Gd-doping, and CNT reinforcement approaches have been adopted to develop a rationally designed electrode with a high surface area, boosted electrical conductivity, and enhanced specific capacitance. Electrochemical impedance spectroscopy, galvanostatic charge/discharge, and cyclic voltammetry processes have been used to measure the electrochemical performance of the prepared ferrite material-based working electrodes in a 3M KOH solution. A nanohybrid-based working electrode (GZFO/C@AF) shows superior rate capacitive and electrochemical aptitude (specific capacitance, rate performance, and cyclic activity) than its counterpart working electrodes (ZFO@AF and GZFO@AF). The hybrid working electrode (GZFO/C@AF electrode) shows a high specific capacitance of 887 F g −1 and good retention of 94.5% for 7000 cycles (at 15 Ag −1). The maximum energy density and power density values for the GZFO/C@AF electrode are 40.025 Wh Kg −1 and 279.78 W Kg −1 , respectively. Based on the findings of the electrochemical experiments, GZFO/C@AF shows promise as an electrode material for hybrid capacitors that provide energy to wearable electronic devices.
  • Xinglin Jia
    Xinglin Jia
  • Gregory J. Phillips
    Gregory J. Phillips
  • Joshua M. Lyte
    Joshua M. Lyte
Avian pathogenic Escherichia coli found in the avian intestinal tract can cause systemic disease in birds and act as a foodborne zoonotic pathogen associated with human disease. Here, we report the complete genome sequence of E. coli strain H1998 isolated from a chicken with colisepticemia.
  • Tristan Sanderson
    Tristan Sanderson
  • Brent M. Phares
    Brent M. Phares
  • Katelyn S. Freeseman
    Katelyn S. Freeseman
  • Zhengyu Liu
    Zhengyu Liu
Earth pressure on concrete box culverts is a key component of design and load-rating decisions. The American Association of State Highway and Transportation Officials has revised the design guidelines over the years to impose greater design/rating earth pressures for buried structures. Currently, the Iowa Department of Transportation uses the maximum and minimum lateral earth pressure of 36/18 lb/ft3 specified for load factor design (LFD) and allowable stress design (ASD) and 60/30 lb/ft3 for load and resistance factor design (LRFD). The objective of this research is to monitor and evaluate the real earth pressures acting on deep-buried culvert structures. To achieve this objective, two concrete box culverts–one in Ida County and the other in Crawford County–were monitored for more than 2.5 years and 1 year, respectively, to identify the realistic design soil pressure. The captured pressure, strain, and temperature data were analyzed to find the relation between the temperature and earth pressure experienced by the culverts. The measured vertical and lateral pressures were compared with the specified design pressure loading. The monitoring results from both culverts led to the consistent conclusion that the earth pressure experienced by the culverts was two to six times that of the design values with the LRFD and LFD/ASD methods. This paper revealed that the earth pressure acting on the deeply embedded culvert could be higher than the design-specified value. Further research was recommended to investigate the relation between the soil weight and culvert vertical/lateral pressure for Iowa design specifications.
  • Forrest F. Williams
    Forrest F. Williams
  • Peter L. Moore
    Peter L. Moore
  • Jade V. Allen
    Jade V. Allen
  • [...]
  • Keith Schilling
    Keith Schilling
In this study, a new remote sensing tool was used in conjunction with sampling of river bank sediments to map channel migration patterns and estimate the net contribution of bank erosion to the sediment and phosphorus (P) budget of the Nishnabotna River in southwestern Iowa. Between the years 2009 and 2018, we found that at least 1.81 ± 0.57 × 10 ⁷ Mg of sediment and 8.26 ± 2.5 × 10 ³ Mg of P entered the Nishnabotna River due to channel migration. This equates to 0.87 Mg of sediment per meter of channel per year and 0.40 kg of P per meter of channel per year. Barring additional deposition elsewhere in the river corridor, these values represent as much as 77% of annual suspended sediment and 46% of the annual P export from the watershed. Our results also indicate that the contribution of net sediment and P volume loss by stream order increases sharply from third to sixth order, even though the total channel length is much smaller in the higher orders. These results suggest that bank erosion is an important source of sediment and P within the watershed and that future attempts to decrease riparian exports of sediment and P should focus on high‐order reaches.
The nonlinear behavior of reinforced concrete beams is complex due to their heterogenic properties and crack formations. Thus, a more accurate estimation through experimental testing and nonlinear finite element modeling is necessary to understand better such behavior. Experimental testing of a reinforced concrete beam subjected to monotonic loading was conducted in laboratory. The test specimen along with seven specimens from various literature were then modeled and analyzed using VecTor2 software to investigate the capability of the software in predicting the load-displacement curves and crack patterns of the specimens. The analysis results show that the finite element model used in VecTor2 software is able to predict well the load-displacement curves and crack patterns of the specimens failing in flexure and shear mechanisms.
Climate change is causing an increase in drought in many soil ecosystems and a loss of soil organic carbon. Calcareous soils may partially mitigate these losses via carbon capture and storage. Here, we aimed to determine how irrigation-supplied soil moisture and perennial plants impact biotic and abiotic soil properties that underpin deep soil carbon chemistry in an unfertilized calcareous soil. Soil was sampled up to 1 m in depth from irrigated and planted field treatments and was analyzed using a suite of omics and chemical analyses. The soil microbial community composition was impacted more by irrigation and plant cover treatments than by soil depth. By contrast, metabolomes, lipidomes, and proteomes differed more with soil depth than treatments. Deep soil (>50 cm) had higher soil pH and calcium concentrations and higher levels of organic acids, bicarbonate, and triacylglycerides. By contrast, surface soil (0–5 cm) had higher concentrations of soil organic matter, organic carbon, oxidizable carbon, and total nitrogen. Surface soils also had higher amounts of sugars, sugar alcohols, phosphocholines, and proteins that reflect osmotic and oxidative stress responses. The lipidome was more responsive to perennial tall wheatgrass treatments compared to the metabolome or proteome, with a striking change in diacylglyceride composition. Permanganate oxidizable carbon was more consistently correlated to metabolites and proteins than soil organic and inorganic carbon and soil organic matter. This study reveals specific compounds that reflect differences in organic, inorganic, and oxidizable soil carbon fractions that are impacted by interactions between irrigation-supplied moisture and plant cover in calcareous soil profiles. IMPORTANCE Carbon is cycled through the air, plants, and belowground environment. Understanding soil carbon cycling in deep soil profiles will be important to mitigate climate change. Soil carbon cycling is impacted by water, plants, and soil microorganisms, in addition to soil mineralogy. Measuring biotic and abiotic soil properties provides a perspective of how soil microorganisms interact with the surrounding chemical environment. This study emphasizes the importance of considering biotic interactions with inorganic and oxidizable soil carbon in addition to total organic carbon in carbonate-containing soils for better informing soil carbon management decisions.
The purpose of our study was to determine whether the application of quinone outside inhibitor (QoI) and pyrazole-carboxamide fungicides as a tank mix would impact the endophyte community of soybean seed. Field trials during 2018 in Iowa, South Dakota, and Wisconsin, USA, investigated the impact of a single combination fungicide spray at early pod set in soybeans. The composition of culturable endophytic fungi in mature soybean seed was assessed on three cultivars per state, with maturity groups (MG) ranging from 1.1 to 4.7. An unusually wet 2018 season delayed harvest, leading to a high level of fungal growth in grain. The survey included 1,080 asymptomatic seeds that were disinfested and individually placed on 5-cm-diameter Petri plates of acidified water agar. The survey yielded 721 fungal isolates belonging to 24 putative species in seven genera; taxa were grouped into genera based on a combination of morphological and molecular evidence. The dominant genera encountered in the survey were Alternaria, Diaporthe, and Fusarium. The study showed that the fungicide treatment reduced the incidence of Fusarium in Wisconsin seed, increased the incidence of Diaporthe in seed from all states, and had no impact on the incidence of Alternaria. This is one of the first attempts to characterize the diversity of seed endophytes in soybean, and the first to characterize the impacts of fungicide spraying on these endophyte communities across three states. Our study provides evidence that the impact of a fungicide spray on soybean seed endophyte communities may be influenced by site, weather, and cultivar maturity group.
Malignant peripheral nerve sheath tumours (MPNST) of a plexus nerve or nerve root cause significant morbidity and present a treatment challenge. The surgical approach can be complex and information is lacking on outcomes. The objective of this study was to describe surgical complication rates and oncologic outcomes for canine MPNST of the brachial or lumbosacral plexus. Dogs treated for a naïve MPNST with amputation/hemipelvectomy with or without a laminectomy were retrospectively analysed. Oncologic outcomes were disease free interval (DFI), overall survival (OS), and 1‐ and 2‐year survival rates. Thirty dogs were included. The surgery performed was amputation alone in 17 cases (57%), and amputation/hemipelvectomy with laminectomy in 13 cases (43%). Four dogs (13%) had an intraoperative complication, while 11 dogs (37%) had postoperative complications. Histologic margins were reported as R0 in 12 dogs (40%), R1 in 12 dogs (40%), and R2 in five dogs (17%). No association was found between histologic grade and margin nor extent of surgical approach and margin. Thirteen dogs (46%) had recurrence. The median DFI was 511 days (95% CI: 140–882 days). The median disease specific OST was 570 days (95% CI: 467–673 days) with 1‐ and 2‐year survival rates of 82% and 22% respectively. No variables were significantly associated with recurrence, DFI, or disease specific OST. These data show surgical treatment of plexus MPNST was associated with a high intra‐ and postoperative complication rate but relatively good disease outcomes. This information can guide clinicians in surgical risk management and owner communication regarding realistic outcomes and complications.
Filarial nematode infections are a major health concern in several countries. Lymphatic filariasis is caused by Wuchereria bancrofti and Brugia spp. affecting over 120 million people. Heavy infections can lead to elephantiasis, which has serious effects on individuals’ lives. Although current anthelmintics are effective at killing microfilariae in the bloodstream, they have little to no effect against adult parasites found in the lymphatic system. The anthelmintic diethylcarbamazine is one of the central pillars of lymphatic filariasis control. Recent studies have reported that diethylcarbamazine can open transient receptor potential (TRP) channels in the muscles of adult female Brugia malayi, leading to contraction and paralysis. Diethylcarbamazine has synergistic effects in combination with emodepside on Brugia, inhibiting motility: emodepside is an anthelmintic that has effects on filarial nematodes and is under trial for the treatment of river blindness. Here, we have studied the effects of diethylcarbamazine on single Brugia muscle cells by measuring the change in Ca ²⁺ fluorescence in the muscle using Ca ²⁺ -imaging techniques. Diethylcarbamazine interacts with the transient receptor potential channel, C classification (TRPC) ortholog receptor TRP-2 to promote Ca ²⁺ entry into the Brugia muscle cells, which can activate Slopoke (SLO-1) Ca ²⁺ -activated K ⁺ channels, the putative target of emodepside. A combination of diethylcarbamazine and emodepside leads to a bigger Ca ²⁺ signal than when either compound is applied alone. Our study shows that diethylcarbamazine targets TRP channels to promote Ca ²⁺ entry that is increased by emodepside activation of SLO-1 K ⁺ channels.
This paper presents a range of novel reinforcement learning algorithms derived from the actor–critic approach. These modified algorithms effectively utilize the available information to enhance performance. Our proposed framework introduces several key components to the traditional actor–critic model, including an underlying model learner, selector, tuner, and estimator. The estimator employs an approximate value function and the learned underlying model to estimate the values of all actions at the next state. The selector approximates the optimal action at the next state, which is then utilized by the actor to optimize its policy. In contrast to the conventional actor–critic algorithm where the actor focuses solely on policy optimization and the critic performs value-function approximation and policy evaluation, our selector–actor–critic algorithm employs a selector to approximate the optimal action at the current state, thereby influencing the actor’s policy updates. Furthermore, our tuner–actor–critic algorithm incorporates a critic and a model-learner to approximate the action-value function and the dynamics of the underlying environment, respectively. The tuner then utilizes this information to adjust the value of the current state–action pair. In the estimator–selector–actor–critic algorithm, we develop intelligent agents based on the concepts of lookahead and intuition. Lookahead is utilized in estimating the values of available actions at the next state, while intuition guides the maximization of the probability of selecting the approximate optimal action. Through simulation experiments, we evaluate the performance of these algorithms, and the results demonstrate the superiority of the estimator–selector–actor–critic approach over other existing algorithms.
Information leakage is usually defined as the logarithmic increment in the adversary’s probability of correctly guessing the legitimate user’s private data or some arbitrary function of the private data when presented with the legitimate user’s publicly disclosed information. However, this definition of information leakage implicitly assumes that both the privacy mechanism and the prior probability of the original data are entirely known to the attacker. In reality, the assumption of complete knowledge of the privacy mechanism for an attacker is often impractical. The attacker can usually have access to only an approximate version of the correct privacy mechanism, computed from a limited set of the disclosed data, for which they can access the corresponding un-distorted data. In this scenario, the conventional definition of leakage no longer has an operational meaning. To address this problem, in this paper, we propose novel meaningful information-theoretic metrics for information leakage when the attacker has incomplete information about the privacy mechanism – we call them average subjective leakage , average confidence boost , and average objective leakage , respectively. For the simplest, binary scenario, we demonstrate how to find an optimized privacy mechanism that minimizes the worst-case value of either of these leakages.
Scalable quantum algorithms for the simulation of quantum many-body systems in thermal equilibrium are important for predicting properties of quantum matter at finite temperatures. Here we describe and benchmark a quantum computing version of the minimally entangled typical thermal states (METTS) algorithm for which we adopt an adaptive variational approach to perform the required quantum imaginary time evolution. The algorithm, which we name AVQMETTS, dynamically generates compact and problem-specific quantum circuits, which are suitable for noisy intermediate-scale quantum (NISQ) hardware. We benchmark AVQMETTS on statevector simulators and perform thermal energy calculations of integrable and nonintegrable quantum spin models in one and two dimensions and demonstrate an approximately linear system-size scaling of the circuit complexity. We further map out the finite-temperature phase transition line of the two-dimensional transverse field Ising model. Finally, we study the impact of noise on AVQMETTS calculations using a phenomenological noise model.
Changes in gene expression are thought to play a major role in adaptive evolution. While it is known that gene expression is highly sensitive to the environment, very few studies have determined the influence of genetic and environmental effects on adaptive gene expression differences in natural populations. Here, we utilize allele-specific expression to characterize cis and trans gene regulatory divergence in temperate and tropical house mice in two metabolic tissues under two thermal conditions. First, we show that gene expression divergence is pervasive between populations and across thermal conditions, with roughly 5 to 10% of genes exhibiting genotype-by-environment interactions. Second, we found that most expression divergence was due to cis -regulatory changes that were stable across temperatures. In contrast, patterns of expression plasticity were largely attributable to trans -effects, which showed greater sensitivity to temperature. Nonetheless, we found a small subset of temperature-dependent cis -regulatory changes, thereby identifying loci underlying expression plasticity. Finally, we performed scans for selection in wild house mice to identify genomic signatures of rapid adaptation. Genomic outliers were enriched in genes with evidence for cis -regulatory divergence. Notably, these genes were associated with phenotypes that affected body weight and metabolism, suggesting that cis- regulatory changes are a possible mechanism for adaptive body size evolution between populations. Our results show that gene expression plasticity, largely controlled in trans , may facilitate the colonization of new environments, but that evolved changes in gene expression are largely controlled in cis , illustrating the genetic and nongenetic mechanisms underlying the establishment of populations in new environments.
Premise Current methods for maceration of plant tissue use hazardous chemicals. The new method described here improves the safety of dissection and maceration of soft plant tissues for microscopic imaging by using the harmless enzyme pectinase. Methods and Results Leaf material from a variety of land plants was obtained from living plants and dried herbarium specimens. Concentrations of aqueous pectinase and soaking schedules were optimized, and tissues were manually dissected while submerged in fresh solution following a soaking period. Most leaves required 2–4 h of soaking; however, delicate leaves could be macerated after 30 min while tougher leaves required 12 h to 3 days of soaking. Staining techniques can also be used with this method, and permanent or semi‐permanent slides can be prepared. The epidermis, vascular tissue, and individual cells were imaged at magnifications of 10× to 400×. Only basic safety precautions were needed. Conclusions This pectinase method is a cost‐effective and safe way to obtain images of epidermal peels, separated tissues, or isolated cells from a wide range of plant taxa.
The implementation of livestock into cover crop integrated systems is a sustainable practice that has been shown to improve soil health and system diversity. However, the effects of pasture-raised poultry systems on broiler performance and welfare have not been well-documented. The experimental objective was to compare the performance, physiological, and economic outcomes of Freedom Ranger broilers raised in outdoor pastured versus conventional indoor settings. 176 slow-growing Freedom Ranger broilers were started in brooders for 21d, and then half were transferred to either indoor floor pens or outdoor chicken tractors for a 6 week grow-out cycle. Performance and welfare measures were recorded weekly. At d64, 40 birds per treatment were euthanized for tibia collection, and bone mineral density was analyzed by Dual-energy X-ray Absorptiometry (DXA). Under our research conditions, performance and welfare measures were not significantly affected by housing treatments, but bone mineral content and density were significantly increased by 37.9% and 15.4%, respectively, in the outdoor flock (P<0.05). Future research will investigate the impacts of pasture-raised poultry systems on bird behavior and welfare.
We take another look at intractable temporal logic specifications, where the intractability stems from self-reference, unboundedness, or the need for explicit counting. A classic example is the specification, “Every file that gets opened eventually gets closed.” In all cases, we show that we can capitalize on realistic constraints implied by the operating environment to generate Mission-time Linear Temporal Logic (MLTL) encodings with reasonably-sized memory signatures. We derive a new set of rewriting rules for MLTL, accompanied by proofs of correctness for each rule, and memory optimizations. We utilize these in creating MLTL encodings for all three patterns of “intractability,” proving correctness, time complexity, and space complexity for each type of specification encoding.
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9,951 members
Shan Jiang
  • Department of Materials Science and Engineering
Mahdi Saatchi
  • Department of Animal Science
Peter Orazem
  • Department of Economics
Kambakam Sekhar
  • Department of Genetics, Development and Cell Biology
Sorb Yesudhas
  • Department of Aerospace Engineering
Ames, IA, United States