Temporal Cycling Research Articles

Safety of cyclists interacting with autonomous vehicles: A combined microscopic simulation and SSAM analysis

The aim of this paper is to investigate the safety of cyclists while interacting with autonomous vehicles (AVs) in an uncontrolled T-intersection using PTV Vissim microsimulation combined with the Surrogate Safety Assessment Model (SSAM). For the microsimulation, three cycling behaviours were constructed (cautious, normal, and aggressive), and two AV behaviours (cautious and normal) were adopted. 87 h of microsimulation resulted in 230 conflicts. The type and nature of these conflicts, as well as two temporal indicators and four speed-related indicators were analysed. Nearly 96% of the conflicts were rear-end collisions, and almost 70% were conflicts where the cyclist was the first to arrive at the conflict point. Interestingly, the least involved cycling behaviour in conflicts was aggressive and the most involved was cautious. A significant relationship was found between severity clusters of temporal indicators and cycling behaviour. It is also concluded that an important future research direction would be the construction of a two-dimensional conflict diagram with severity thresholds specifically for bicycle-vehicle interactions.

Artificial consortium demonstrates emergent properties of enhanced cellulosic-sugar degradation and biofuel synthesis

Planktonic cultures, of a rationally designed consortium, demonstrated emergent properties that exceeded the sums of monoculture properties, including a >200% increase in cellobiose catabolism, a >100% increase in glycerol catabolism, a >800% increase in ethanol production, and a >120% increase in biomass productivity. The consortium was designed to have a primary and secondary-resource specialist that used crossfeeding with a positive feedback mechanism, division of labor, and nutrient and energy transfer via necromass catabolism. The primary resource specialist was Clostridium phytofermentans (a.k.a. Lachnoclostridium phytofermentans), a cellulolytic, obligate anaerobe. The secondary-resource specialist was Escherichia coli, a versatile, facultative anaerobe, which can ferment glycerol and byproducts of cellobiose catabolism. The consortium also demonstrated emergent properties of enhanced biomass accumulation when grown as biofilms, which created high cell density communities with gradients of species along the vertical axis. Consortium biofilms were robust to oxic perturbations with E. coli consuming O2, creating an anoxic environment for C. phytofermentans. Anoxic/oxic cycling further enhanced biomass productivity of the biofilm consortium, increasing biomass accumulation ~250% over the sum of the monoculture biofilms. Consortium emergent properties were credited to several synergistic mechanisms. E. coli consumed inhibitory byproducts from cellobiose catabolism, driving higher C. phytofermentans growth and higher cellulolytic enzyme production, which in turn provided more substrate for E. coli. E. coli necromass enhanced C. phytofermentans growth while C. phytofermentans necromass aided E. coli growth via the release of peptides and amino acids, respectively. In aggregate, temporal cycling of necromass constituents increased flux of cellulose-derived resources through the consortium. The study establishes a consortia-based, bioprocessing strategy built on naturally occurring interactions for improved conversion of cellulose-derived sugars into bioproducts.

Loss of Endogenously Cycling Adult Cardiomyocytes Worsens Myocardial Function.

Endogenously cycling adult cardiomyocytes increase after myocardial infarction (MI) but remain scarce and are generally thought not to contribute to myocardial function. However, this broadly held assumption has not been tested, mainly because of the lack of transgenic reporters that restrict Cre expression to adult cardiomyocytes that reenter the cell cycle. We created and validated a new transgenic mouse, αMHC (alpha myosin heavy chain)-MerDreMer-Ki67p-RoxedCre (denoted αDKRC [cardiomyocyte-specific αMHC-MerDreMer-Ki67p-RoxedCre]) that restricts Cre expression to cycling adult cardiomyocytes and uniquely integrates spatial and temporal adult cardiomyocyte cycling events based on the DNA specificities of orthologous Dre and Cre recombinases. We then created αDKRC::DTA mice that expressed an inducible diphtheria toxin in adult cycling cardiomyocytes and examined the effects of ablating these endogenously cycling cardiomyocytes on myocardial function after ischemic-reperfusion (I/R) MI. A tandem αDKRC transgene was designed, validated in cultured cells, and used to make transgenic mice. The αDKRC transgene integrated between MYH6 and MYH7 and did not disrupt expression of the surrounding genes. Compared with controls, αDKRC::RLTG (Rox-Lox-tdTomato-eGFP) mice treated with Tamoxifen expressed tdTomato+ in cardiomyocytes with rare Bromodeoxyuridine+, eGFP+ cardiomyocytes, consistent with reentry of the cell cycle. We then pretreated αDKRC::RLTG mice with Tamoxifen to activate the reporter before sham or reperfusion (I/R) MI surgeries. Compared with Sham surgery, the I/R MI group had increased single and paired eGFP+ (enhanced green fluorescent protein)+ cardiomyocytes predominantly in the border zones (5.8±0.5 versus 3.3±0.3 cardiomyocytes per 10-micron section, N=8-9 mice per group, n=16-24 sections per mouse), indicative of cycled cardiomyocytes. The single to paired eGFP+ cardiomyocyte ratio was ≈9 to 1 (5.2±0.4 single versus 0.6±0.2 paired cardiomyocytes) in the I/R MI group after MI, suggesting that cycling cardiomyocytes were more likely to undergo polyploidy than replication. The ablation of endogenously cycling adult cardiomyocytes in αDKRC::DTA (diphtheria) mice caused progressive worsening left ventricular chamber size and function after I/R MI, compared with controls. Although scarce, endogenously cycling adult cardiomyocytes contribute to myocardial function after injury, suggesting that these cells may be physiologically relevant.

Shifting back and forth: How does the temporal cycling between exploratory and exploitative R&D influence firm performance?

Research on ambidexterity has established that many firms engage in temporal cycling between exploratory and exploitative activities, but it has not examined how quickly firms engage in temporal cycling and how this decision affects their performance. We enhance understanding of this phenomenon by examining how the speed at which innovative firms choose to cycle between exploratory and exploitative R&D influences their performance. We also examine contingencies that affect this relationship. Our longitudinal multi-level analysis of 32,527 observations shows that high-speed temporal cycling decreases firm performance by increasing time compression diseconomies in learning. However, we also show that this relationship is firm- and context-specific. Although high-speed cycling harms firms with large-scale R&D operations, it benefits firms that operate in technologically dynamic industries. Our study shifts the discussion from how much firms invest in exploration and exploitation to how quickly they change their focus from one activity to the other.

Inhibition of IRS-1 Alters Retinal Circadian Clock

Background and Hypothesis: Life on Earth has adapted to a 24-hour cycle of light and darkness. Circadian physiology coordinates temporal metabolism, hormone cycling, and sleep using clock genes. It is documented that dysregulation of clock gene expression is a key factor in the pathogenesis of diabetic retinopathy. Our goal was to explore the relationship between clock genes and the retina in diabetic milieu, and we hypothesized that disrupting downstream insulin signaling in a manner similar to diabetes in the retina would also affect the circadian clock. 
 Experimental Design or Project Methods: In this mouse study, we used a Per2::Luc fusion protein to perform real-time bioluminescent recording of circadian rhythms. We used SecinH3 to inhibit Insulin Receptor Signaling (IRS-1). In isolated retinas, we modulated IRS-1 to mimic the diabetic condition of impaired insulin signaling; this allowed us to directly quantify circadian rhythms in the retina. Results: Our results show that IRS-1 inhibition by SecinH3 altered the gene expression of Per2, a clock regulatory gene, over the controls. There was an increase in the period and an apparent phase shift in the presence of 100uM SecinH3. 
 Conclusion and Potential Impact: Our findings can help us understand the role of insulin signaling on circadian rhythms of the retina and provide another temporal dimension to view diabetic retinopathy disease progression. Ultimately, further studies and a closer understanding of the roles of molecular clocks and insulin signaling may help to develop novel therapeutics for treating some of the harmful effects of diabetes.

Not all Ways Lead to Rome: Different Approaches to Ambidexterity in Acquisition Sequences

While ambidexterity, in general, is argued to be performance enhancing, researchers have found that in the context of acquisitions the added complexity tends to reduce performance. We expand the scope of the analysis from individual acquisitions within a single year to acquisition sequences and examine the performance implications of three different ways to achieve ambidexterity. Based on a panel study of 153 active acquirers from 1991 to 2016, we corroborate the findings of prior research that combining exploration and exploitation in individual acquisitions is not performance enhancing. On the other hand, separating exploration and exploitation to different acquisitions is positively related to acquirer performance and temporal cycling between exploration and exploitation is related to acquirer performance in a U-shaped manner. Our findings contribute to an improved understanding of how to achieve ambidexterity through acquisition sequences.

Iron-Binding Ligands in the Southern California Current System: Mechanistic Studies

The distributions of dissolved iron and organic iron-binding ligands were examined in water column profiles and deckboard incubation experiments in the southern California Current System (sCCS) along a transition from coastal to semi-oligotrophic waters. Analysis of the iron-binding ligand pool by competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) using multiple analytical windows (MAWs) revealed three classes of iron-binding ligands present throughout the water column (L1-L3), whose distributions closely matched those of dissolved iron and nitrate. Despite significant biogeochemical gradients, ligand profiles were similar between stations, with surface minima in strong ligands (L1 and L2), and relatively constant concentrations of weaker ligands (L3) down to 500 m. A phytoplankton grow-out incubation, initiated from an iron-limited water mass, showed dynamic temporal cycling of iron-binding ligands. A biological iron model was able to capture the patterns of the strong ligands in the grow-out incubation relatively well with only the microbial community as a biological source. An experiment focused on remineralization of particulate organic matter showed production of both strong and weak iron-binding ligands by the heterotrophic community, supporting a mechanism for in-situ production of both strong and weak iron-binding ligands in the subsurface water column. Photochemical experiments showed a variable influence of sunlight on the degradation of natural iron-binding ligands, providing some evidence to explain differences in surface ligand concentrations between stations. Patterns in ligand distributions between profiles and in the incubation experiments were primarily related to macronutrient concentrations, suggesting microbial remineralization processes might dominate on longer time-scales over short-term changes associated with photochemistry or phytoplankton growth.

Deciphering principles of morphogenesis from temporal and spatial patterns on the integument.

How tissue patterns form in development and regeneration is a fundamental issue remaining to be fully understood. The integument often forms repetitive units in space (periodic patterning) and time (cyclic renewal), such as feathers and hairs. Integument patterns are visible and experimentally manipulatable, helping us reveal pattern formative processes. Variability is seen in regional phenotypic specificities and temporal cycling at different physiological stages. Here we show some cellular/molecular bases revealed by analyzing integument patterns. (1) Localized cellular activity (proliferation, rearrangement, apoptosis, differentiation) transforms prototypic organ primordia into specific shapes. Combinatorial positioning of different localized activity zones generates diverse and complex organ forms. (2) Competitive equilibrium between activators and inhibitors regulates stem cells through cyclic quiescence and activation. Dynamic interactions between stem cells and their adjacent niche regulate regenerative behavior, modulated by multi-layers of macro-environmental factors (dermis, body hormone status, and external environment). Genomics studies may reveal how positional information of localized cellular activity is stored. In vivo skin imaging and lineage tracing unveils new insights into stem cell plasticity. Principles of self-assembly obtained from the integumentary organ model can be applied to help restore damaged patterns during regenerative wound healing and for tissue engineering to rebuild tissues. Developmental Dynamics 244:905-920, 2015. © 2015 Wiley Periodicals, Inc.

Flood-related contamination in catchments affected by historical metal mining: An unexpected and emerging hazard of climate change

Floods in catchments affected by historical metal mining result in the remobilisation of large quantities of contaminated sediment from floodplain soils and old mine workings. This poses a significant threat to agricultural production and is preventing many European river catchments achieving a ‘good chemical and ecological status’, as demanded by the Water Framework Directive. Analysis of overbank sediment following widespread flooding in west Wales in June 2012 showed that flood sediments were contaminated above guideline pollution thresholds, in some samples by a factor of 82. Most significantly, silage produced from flood affected fields was found to contain up to 1900mgkg−1 of sediment associated Pb, which caused cattle poisoning and mortality. As a consequence of climate related increases in flooding this problem is likely to continue and intensify. Management of contaminated catchments requires a geomorphological approach to understand the spatial and temporal cycling of metals through the fluvial system.

Simultaneous Pursuit of Innovation and Efficiency in Complex Engineering Projects—A Study of the Antecedents and Impacts of Ambidexterity in Project Teams

Projects, as the common unit of organizing complex tasks, often feature unique challenges that require both radical innovation and incremental improvements to processes and solutions in order to deliver the project within constraints. Both exploration and exploitation are likely to be needed for complex engineering projects to succeed. This study, through an in-depth case study of a complex infrastructure project facing unique challenges and tight budget and schedule, investigates the antecedents of ambidexterity and the effect of ambidexterity on project performance. The main contributions of this research include finding: (1) ambidexterity at the project team level to be a significant contributor to project performance; (2) the effects of temporal separation and project context on project performance are mediated by the project team's degree of ambidexterity; and (3) contrary to the prediction from organizational literature, structural separation has not contributed to the case project team's ambidexterity. The authors believe that among the three antecedents for ambidexterity at the project level as predicted by organizational literature, structural separation is rendered ineffective by the natural cycling between exploration and exploitation in the project environment and by the need to integrate the two under time pressure and resource constraints. The development of an effective project context can facilitate the temporal cycling between exploration and exploitation by creating awareness that overcomes the inertia in transitioning between the two by setting performance expectations and appropriate social context. Implications for theory development and practice are discussed.

Temporal and diel cycling of nutrients in a barrier–lagoon complex: Implications for phytoplankton abundance and composition

The cycling of nutrients (silicate, nitrate, ammonium and phosphate) in a quasi-pristine barrier–lagoon complex (Louro Lagoon, NW Iberian Peninsula) was studied both in a diel and temporal timescale covering different seasonal conditions. Hydrographical and meteorological conditions exert a major control on the nutrient cycling in the lagoon. From late autumn to early spring the lagoon is characterized by oxic conditions due to significant freshwater inputs and sporadic communication with the sea. In summer, elevated primary production coupled with water stagnancy leads to bottom waters hypoxia and marked diel variation of pH, oxygen and redox potentials. Diel variation of nutrients was only evident when mixing of surface and bottom waters during the night was observed.Temporal changes in nutrients concentrations and their relative abundance were found to induce a clear shift in the phytoplankton composition. In winter, during silicate and nitrate abundance and low phosphate, diatoms predominate. In summer, under hypoxic conditions, sediments take control on the supply of nutrients leading to increased phosphate availability relative to nitrate/ammonium or silicate. Diatoms are then replaced during the summer blooms – linked to low atomic N:P ratios (typically <2) – by flagellates and green algae with minor contributions of cyanophytes and dinoflagellates.

Rapid Cycling Associated With Menstrual Periods in an Adolescent: Electrophysiological Underpinnings for Bipolarity

Rapid Cycling Associated With Menstrual Periods in an Adolescent: Electrophysiological Underpinnings for Bipolarity

Roles of Dopamine in Circadian Rhythmicity and Extreme Light Sensitivity of Circadian Entrainment

Light has profound behavioral effects on almost all animals, and nocturnal animals show sensitivity to extremely low light levels [1-4]. Crepuscular, i.e., dawn/dusk-active animals such as Drosophila melanogaster are thought to show far less sensitivity to light [5-8]. Here we report that Drosophila respond to extremely low levels of monochromatic blue light. Light levels three to four orders of magnitude lower than previously believed impact circadian entrainment and the light-induced stimulation of locomotion known as positive behavioral masking. We use GAL4;UAS-mediated rescue of tyrosine hydroxylase (DTH) mutant (ple) flies to study the roles of dopamine in these processes. We present evidence for two roles of dopamine in circadian behaviors. First, rescue with either a wild-type DTH or a DTH mutant lacking neural expression leads to weak circadian rhythmicity, indicating a role for strictly regulated DTH and dopamine in robust circadian rhythmicity. Second, the DTH rescue strain deficient in neural dopamine selectively shows a defect in circadian entrainment to low light, whereas another response to light, positive masking, has normal light sensitivity. These findings imply separable pathways from light input to the behavioral outputs of masking versus circadian entrainment, with only the latter dependent on dopamine.

Thermocapillary actuation of liquid plugs using a heater array

With the aim toward realizing polymerase chain reaction (PCR) of deoxyribonucleic acid (DNA) in plug-based capillary platforms, this paper reports the theoretical and experimental results of thermocapillary actuation for temperature cycling with an arbitrary ramping function. Two concepts were investigated: (a) actuation and spatial temperature cycling with three heaters and (b) actuation and temporal cycling with two heaters. The paper first describes the analytical models of both concepts. The model considers the spatio-temporal heat transfer effects, which is coupled with the surface tension driven movement of the plug. In the experiments, both temperature field and plug motion were measured and evaluated. The temperature field was captured by an infrared thermal tracer camera. The position of the plugs was automatically captured and evaluated with a CCD camera. Finally, analytical and experimental results are compared and discussed.

Changes in agonistic, courtship and parental displays of the male brook stickleback, Culaea inconstans, across the breeding cycle

Although the individual elements of stickleback behaviour are well known, to date a robust investigation of the temporal cycling of aggressive, courtship and parental behaviour during the breeding cycle has been undertaken in only one species, the threespine stickleback, Gasterosteus aculeatus. In order to understand the evolution of behaviour in this fascinating group of fishes, comparative studies conducted upon other members of the Gasterosteidae are necessary. We thus documented the cyclic changes and structure of sixteen agonistic, parental and courtship displays across the breeding cycle for a population of brook sticklebacks, Culaea inconstans, from Nebraska and compared it to the temporal cycling of reproductive behaviour in the threespine. Our results indicate that in the brook stickleback: (1) aggressive behaviour varies temporally in response to a male, but not a female, intruder. (2) During those phases wherein the young are nest bound, aggressive and parental elements are negatively correlated. (3) The location of the focal fish within the tank during the trial is an accurate indicator of his primary motivation and (4), a sex specific differential response to intruding fish is apparent only during the courtship interval.The temporal structure of reproductive behaviour in the brook stickleback mirrors that of the threespine stickleback in three respects: (1) aggressive motivation across the breeding cycle exhibits a U-shaped distribution, with peak levels of aggression occurring in the nest-building stage and final days of parental care. (2) During the courtship phase sexual motivation supercedes aggression in response to the presence of a nuptially coloured female and (3), the pattern of parental fanning shows an inverted U-shaped distribution with peak frequencies coinciding with the hatching of the eggs.

The relative influences of sexual and natural selection upon the evolution of male nuptial colouration in the brook stickleback, Culaea inconstans

(1) Previous research suggests that the temporal cycling of nuptial colour in a population of brook stickleback, Culaea inconstans, from the Atlantic lineage mirrors that described for its close relative, the three-spine stickleback, Gasterosteus aculeatus.(2) We report an alternative cycling of nuptial colour in a population of brook sticklebacks from Nebraska corresponding to the Mississippian lineage. Males in this population do not assume characteristic black nuptial dress during courtship activities but do become highly melanic during the final days of fry guarding.(3) We also report the first evidence of the plesiomorphic nuptial barring pattern in female brook sticklebacks.(4) The loss of the nuptial signal during courtship and its maximal expression during parental care likely reflects fluctuating relative influences of sexual and natural selection vectors and suggests that at least two pathways of colour evolution are operating within the stickleback family.(5) Geographic variability in the nuptial colour signal of the brook stickleback may have significant implications for mate recognition, should allopatric divergent populations be brought back into contact.

Biogeochemical cycles during the species succession from Skeletonema costatum to Alexandrium tamarense in northern Hiroshima Bay

Temporal variations, budgets and cycling patterns of major biophilic elements [phosphorus (P), nitrogen (N) and silicon (Si)] in northern Hiroshima Bay during species succession from Skeletonema costatum to Alexandrium tamarense were documented using data collected on a weekly basis in 1996 and 1997. The budget calculations using a box model were made from the perspective of both particulate formation and decomposition of particulate matter. Thus, the overall circulation patterns of these three elements and their differences were examined in the present study. The turnover time of P was longer than that of N, indicating that the utilization efficiency of P by organisms is low. Along with this, absolute concentrations of dissolved inorganic phosphorus in this season and elemental ratios calculated from various forms of biophilic elements support the idea that DIP is too low for phytoplankton to utilize it. However, the utilization efficiency of P was higher in 1997 than in 1996, when A. tamarense formed a more intensive bloom, suggesting that these organisms could retain elements. When the bloom of A. tamarense formed in 1997, the residence time of water was extremely long, indicating that stagnation of water is a primary factor for bloom formation. In contrast to the large fluctuation in the residence time of water, residence times of biophilic elements were almost constant, indicating the importance of biological processes occurring in the system. On the other hand, in 1996, the residence times of biophilic elements were usually longer compared to that of water. This suggests that the particulate formation process by phytoplankton acts as a “nutrient trap” in combination with estuarine circulation.

The legacy of biosphere 2 for the study of biospherics and closed ecological systems

The unprecedented challenges of creating Biosphere 2, the world's first laboratory for biospherics, the study of global ecology and long-term closed ecological system dynamics, led to breakthrough developments in many fields, and a deeper understanding of the opportunities and difficulties of material closure. This paper will review accomplishments and challenges, citing some of the key research findings and publications that have resulted from the experiments in Biosphere 2. Engineering accomplishments included development of a technique for variable volume to deal with pressure differences between the facility and outside environment, developing methods of atmospheric leak detection and sealing, while achieving new standards of closure, with an annual atmospheric leakrate of less than 10%, or less than 300 ppm per day. This degree of closure permitted detailed tracking of carbon dioxide, oxygen, and trice gases such as nitrous oxide and ethylene over the seasonal variability of two years. Full closure also necessitated developing new approaches and technologies for complete air, water, and wastewater recycle and reuse within the facility. The development of a soil-based highly productive agricultural system was a first in closed ecological systems, and much was learned about managing a wide variety of crops using non-chemical means of pest and disease control. Closed ecological systems have different temporal biogeochemical cycling and ranges of atmospheric components because of their smaller reservoirs of air, water and soil, and higher concentration of biomass, and Biosphere 2 provided detailed examination and modeling of these accelerated cycles over a period of closure which measured in years. Medical research inside Biosphere 2 included the effects on humans of lowered oxygen: the discovery that human productivity can be maintained with good health with lowered atmospheric oxygen levels could lead to major economies on the design of space stations and planetary/lunar settlements. The improved health resulting from the calorie-restricted but nutrient dense Biosphere 2 diet was the first such scientifically controlled experiment with humans. The success of Biosphere 2 in creating a diversity of terrestrial and marine environments, from rainforest to coral reef, allowed detailed studies with comprehensive measurements such that the dynamics of these complex biomic systems are now better understood. The coral reef ecosystem, the largest artificial reef ever built, catalyzed methods of study now being applied to planetary coral reef systems. Restoration ecology advanced through the creation and study of the dynamics of adaptation and self-organization of the biomes in Biosphere 2. The international interest that Biosphere 2 generated has given new impetus to the public recognition of the sciences of biospheres (biospherics), biomes and closed ecological life systems. The facility, although no longer a materially-closed ecological system, is being used as an educational facility by Columbia University as an introduction to the study of the biosphere and complex system ecology and for carbon dioxide impacts utilizing the complex ecosystems created in Biosphere '.The many lessons learned from Biosphere 2 are being used by its key team of creators in their design and operation of a laboratory-sized closed ecological system, the Laboratory Biosphere, in operation as of March 2002, and for the design of a Mars on Earth ™ prototype life support system for manned missions to Mars and Mars surface habitats. Biosphere 2 is an important foundation for future advances in biospherics and closed ecological system research.

Comparative chemical attributes of native North American hop, Humulus lupulus var. lupuloides E. Small

The genetic diversity of 159 representative genotypes of native hop ( Humulus lupulus var. lupuloides E. Small, Cannabaceae) from 34 selected populations was assessed by relative magnitudes and ranges of alpha acids (AA), beta acids (BA), and the cohumulone (CoH) component of alpha acids, with reference to temporal changes between 1989–1990 and 2001, and to the same attributes in American and European hop cultivars, principally H. lupulus var. lupulus L. Chemical profiles of these genotypes were generated by high pressure liquid chromatography (HPLC) of methanol extracts from their processed samples (cones). The alpha ratio (AR, alpha acids / alpha+beta acids) measured the degree to which alpha acids predominated in cone extracts. Synchronous ranges of AR and CoH were also selected for graphic portrayals of native hop genotypic diversity. Cones sampled and analyzed from eight populations that were accessible in both 1989 and 2001 were distinct in chemical attributes, indicating a succession of genotypes, and suggesting temporal cycling of H. lupulus var. lupuloides germplasm. The principal distinctions between the two sub-species were a markedly higher proportion of CoH (38–88% vs. 19–41%) in alpha acids of H. l. var. lupuloides, and generally higher concentrations of AA in cultivars of both American and European commercial hop cultivars, predominantly H. lupulus var. lupulus. All of the 159 native hop genotypes also contained detectable levels of xanthohumol and xanthogalenol, prenylflavonoids recently reported to have mammalian anti-cancer activity. Some native genotypes had previously exhibited natural repellence of insect and mite pests; thus H. lupulus var. lupuloides germplasm offers a diverse resource of underutilized and yet undefined biochemicals.

Feasibility study of long-term continuous field measurement of soil redox potential

An in situ and continuous redox potential measurement protocol for soils and groundwater was optimized, as part of a research that assays the redox potential changes in recharge basin soils during wastewater reclamation using the Soil Aquifer Treatment (SAT). The results show that it is possible to measure continuously and reliably the redox potential in the soil profile of the recharge basins and in the groundwater by using a combined Pt‖Ag|AgCl cell (electrode), a specialized interface, and a portable data-logger. Redox potential values measured before true local equilibration of the electrodes was reached are interpreted as “mixed-potentials” strongly biased by the presence of oxygen near the electrode. Uninterrupted and non-disturbing measurements were carried out in the field for relatively long periods (few days to few weeks) giving reliable information on the temporal cycling of the redox potential in the soil profile during wastewater recharge cycles. The method was found to be dependable, non-expensive and easy to apply.