Apparent Susceptibility Research Articles

The dating of petroleum fluid residence time in subsurface reservoirs. Part 1: A radiolysis-based geochemical toolbox

The radiometric dating of geological events was a crucial achievement leading to the establishment of the geological time scale. The dating of the timing of petroleum charge into, and the determination of petroleum residence times in a geological trap would also be significant, as it would remove ubiquitous speculation concerning the history of reservoir charging in any basin setting. A thorough review of prior strategies to estimate the residence time of petroleum fluids in subsurface reservoirs revealed that few if any methods currently used provide useful estimates of the residence age of fluids. This paper is focused on the age dating of petroleum residence time in reservoirs based on the compositional alterations of reservoired fluids caused by natural radiation. This preliminary paper sets out the geochemical landscape and constraints on radiation-based age dating proxies. We report results on the propagation of radiation through reservoir rocks, which indicate that gamma radiolysis is a primary route to crude oil alteration. Gamma ray radiolysis experiments on crude oils at both natural and elevated radiation doses have been completed and the changing crude oil composition observed using LC, GC-MS and NMR. Reservoir fluids are naturally immersed in radioactive subsurface media that cause systematic alteration to crude oil composition with time, but the chemical changes are small in most natural settings. The degree of radiolysis of individual petroleum compounds was found to depend on chemical class, molecular size, initial compound concentration and the nature of the oil matrix, indicating that a proxy system for dating of petroleum charge times and oil residence times in petroleum traps will likely depend on case-specific calibrations. We define the apparent gamma ray radiolysis susceptibility (kGy−1) of different compounds. Large alkanes, such as high molecular weight normal alkanes (>C22) or hopanes, have high radiolysis susceptibility and show the most rapid decrease in component concentration with increasing radiation dose. In contrast, condensed aromatic hydrocarbons and diamondoid hydrocarbons are more resistant to decomposition through radiolysis. While assessing the decrease in concentration of a compound through radiolysis is a practical objective, it is more difficult to assess the production of new, unique radiolysis products given the great diversity and low concentrations of individual compounds produced. However, monitoring the production of specific functional groups during radiolysis of crude oils, using NMR spectroscopy, was found to be a feasible proxy analytical target. Analysis of newly generated carbon-carbon double bonds in bulk crude oils may represent an optimal approach for development as a radiolysis proxy. We propose a route to assessing in-reservoir crude oil radiation dose.

Mapping of apparent susceptibility yields promising diagnostic separation of progressive supranuclear palsy from other causes of parkinsonism

There is a need for methods that distinguish Parkinson’s disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), which have similar characteristics in the early stages of the disease. In this prospective study, we evaluate mapping of apparent susceptibility based on susceptibility weighted imaging (SWI) for differential diagnosis. We included 134 patients with PD, 11 with PSP, 10 with MSA and 44 healthy controls. SWI data were processed into maps of apparent susceptibility. In PSP, apparent susceptibility was increased in the red nucleus compared to all other groups, and in globus pallidus, putamen, substantia nigra and the dentate nucleus compared to PD and controls. In MSA, putaminal susceptibility was increased compared to PD and controls. Including all studied regions and using discriminant analysis between PSP and PD, 100% sensitivity and 97% specificity was achieved, and 91% sensitivity and 90% specificity in separating PSP from MSA. Correlations between putaminal susceptibility and disease severity in PD could warrant further research into using susceptibility mapping for monitoring disease progression and in clinical trials. Our study indicates that susceptibility in deep nuclei could play a role in the diagnosis of atypical parkinsonism, especially in PSP.

Neanderthal Eustachian tube morphology lowered population‐wide fitness and contributed to extinction

Among modern humans, otitis media (benign otitis media with effusion and acute otitis media, AOM) is the second most common pediatric clinical conditions. Acute otitis media is a fatal disease that can result in meningitis and pneumonia if untreated. Osteological signs of this disease may be found in erosion patterns on the middle ear ossicles, ossification of the tympanic membrane, and a lack of mastoid pneumatization. Recent studies report that nearly all known Neanderthal ossicles exhibit erosion patterns consistent with chronic AOM. To account for the anatomical basis of this apparent disease susceptibility, we assessed the morphological configuration of the cartilaginous Eustachian tube (CET) and dilator tubae (DT) musculature among a modern human growth series ranging from newborns to adults (n=442) and a sample of Neanderthals (La Chapelle aux Saints 1, La Ferrassie 1, Forbes Quarry 1, Saccopastore 1, Guattari 1) and mid‐Pleistocene pre‐Neanderthals (Atapuerca 5 and Steinheim 1). We performed morphometric analysis of the bony upper respiratory tract boundaries. A total of 31 bilateral and midline 3D landmarks were used and coordinate data were subjected to Procrustes‐fitting for geometric morphometric analysis and calculation of univariate measures.Neanderthals exhibited tall narrow choanae and greater overall robusticity. La Ferrassie 1 and Forbes Quarry 1 possessed extremely infant‐like CET orientation relative to the Frankfurt Horizontal Plane while other specimens had adult‐like or intermediate orientation. Choanal orientation among all Neanderthals was horizontal as among human infants. This trait occurred alongside a relatively adult‐like elongation and vertical orientation of the DT whereas the pre‐Neanderthals were distinguished primarily by an extremely short DT relative to Neanderthals and modern humans.The morphological configuration of Neanderthals was unlike any modern human population or growth stage. Differences between these groups appear to be species‐level with Neanderthals retaining infant‐like horizontal orientation of both the choanae and (among some) CET into adulthood. Neanderthal children were probably susceptible to AOM for longer periods of development. While modern human children experience steep reduction in disease occurrence at approximately six years of age with changes in both CET length and orientation, Neanderthal children would have remained susceptible as there was no such growth change in CET orientation. This could have impacted population‐wide fitness when sympatric modern humans invaded Neanderthal habitats and competed for limited resources. AOM should thus be considered among the many potential factors involved in the extinction of the Neanderthals.Support or Funding InformationNational Science Foundation, Grant number 1128901This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria

Abstract The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.

Tensile and Fracture Behaviors of Austenitic High-Manganese Steels Subject to Different Hydrogen Embrittlement Test Methods

The hydrogen embrittlement susceptibility of austenitic high-manganese steels according to different hydrogen charging test methods was discussed in terms of hydrogen embrittlement process and fracture mechanism. Ex-situ electrochemical and high-pressure thermal hydrogen charging methods exhibited a difference in hydrogen embrittlement susceptibility because they affect the permeability and diffusivity of hydrogen. Moreover, the in-situ high-pressure gaseous hydrogen charging method showed the most apparent hydrogen embrittlement susceptibility because higher triaxial stress in the necked region caused by plastic instability accelerates hydrogen charging in the specimen during tensile testing in hydrogen environment, thus leading to intergranular fracture at all regions of the specimens.

CCR4-dependent reduction in the number and suppressor function of CD4+Foxp3+ cells augments IFN-\u03b3-mediated pulmonary inflammation and aggravates tuberculosis pathogenesis

Chronic pulmonary inflammation marked predominantly by CD4+IFN-γ+ cells is the hallmark of tuberculosis pathogenesis in immunocompetent adults, who are substantially affected by this disease. Moreover, CD4+Foxp3+ cell-mediated suppression contributes to infection susceptibility. We addressed the role of CD4+Foxp3+ cells in tuberculosis pathogenesis, because this aspect has not been addressed during chronic infection. We targeted CCR4, which induces the influx of CD4+Foxp3+ cells into the lungs. CCR4−/− mice exhibited a lower frequency of CD4+Foxp3+ cells at 15, 30, and 70 days of infection than their wild-type counterparts. However, only at 70 days of infection was an exacerbated IFN-γ-mediated immune response associated with apparent tuberculosis pathogenesis and susceptibility. In addition, CCR4−/− mice exhibited a decrease in the suppressor function of CD4+Foxp3+ cells. Adoptive transfer of Foxp3+ cells into infected CCR4−/− mice restored pulmonary inflammation and bacterial load to levels observed in wild-type mice. Our findings suggest that CD4+Foxp3+ cells play a time-dependent role in tuberculosis and highlight that CCR4 plays a critical role in the balance of IFN-γ-mediated inflammation by regulating the influx and function of CD4+Foxp3+ cells. Our findings are translationally relevant, as CD4+Foxp3+ cells or CCR4 could be a target for immunotherapy, considering the heterogeneity of tuberculosis in immunocompetent adults.

An examination of the differential susceptibility pattern of the dentition to linear enamel hypoplasia

Enamel hypoplasia is a dental pathology that forms when an individual is exposed to physiological stress in early life while tooth crowns are developing. Biological anthropologists utilize these enamel defects as indicators of growth interruption and interpret them as reflective of factors pertaining to health status and cultural practices that influence health. Over decades of research, numerous studies have noted a pattern in the distribution of linear enamel hypoplasia across the dentition. It is suggested that the anterior dentition presents the highest frequency of defects, followed by the premolars, with molars most rarely exhibiting hypoplasia. This apparent differential susceptibility pattern has resulted in the preferential study of the anterior dentition in anthropology, however little research has been conducted into the validity or cause of this developmental phenomenon. Through examination of the literature, the observed higher frequency of enam2el hypoplasia in the anterior dentition substantiates the existence of this differential distribution pattern. Further investigation reveals that the cause of this varying susceptibility has not been sufficiently explored, leading to a number of inconclusive explanations. Examination of these theories – ranging from the chronology of tooth development, specifics of crown morphology, and variations in genetic control – indicate that there is no single causal variable, but that a multitude of factors are responsible. From this research it is apparent that further study is necessary to fully understand why the anterior teeth appear to be more susceptible to hypoplastic defects than their posterior counterparts.

ESTIMATION OF SOURCE PARAMETERS IN IBADAN, SOUTH – WESTERN NIGERIA USING DIGITIZED AEROMAGNETIC DATA

Airborne magnetic data covering geographical latitudes of 7000‟N to 7030‟N and longitudes of 3 30′E to 4 00′E within Ibadan area were obtained from Nigeria Geology Survey Agency. The data were ana-lyzed to map the sub surface structure and the source parameters were deduced from the quantitative and qualitative interpretation of magnetic data. The upward continuation technique was used to de-emphasize short – wavelength anomaly while the depth to magnetic sources in the area was deter-mined using local wavenumber technique, the analytic signal was also employed to obtain the depths of the magnetic basement. Analysis involving the local wavenumber, upward continuation and appar-ent magnetic susceptibility techniques significantly improves the interpretation of magnetic data in terms of delineating the geological structure, source parameter and magnetic susceptibility within Iba-dan area.. These depth ranges from 0.607km to 2.48km. The apparent susceptibility map at the cut-off wavelength of 50 m ranges from -0.00012 to 0.00079 which agree with the susceptibility value of some rock types; granite gneiss, migmatite biotite gneiss, biotite muscovite granite, hornblende granite, quartz and schists. The result of the local wavenumber suggests variation along the profiles in the surface of magnetic basement across the study area.

Influences of aging conditions on the rheological properties of asphalt binders

ABSTRACTReliable assessment of asphalt binder aging is important for material selection and the prediction of asphalt property changes in field pavements. The apparent property changes of asphalt binder with aging, however, are affected by aging conditions. In this study, three aging treatment methods were applied to five types of asphalt binders, and the longest aging treatment period lasted for 1.5 years. Asphalt binder samples obtained during the aging treatment processes were systematically tested for dynamic rheological properties. The apparent aging susceptibility of asphalt binders was found to be affected by aging conditions. Thin-film aging under a more ‘natural’ condition appears to be quite effective in accelerating the aging process. The changes of the coefficients in the Christensen-Anderson model and the Williams–Landel–Ferry equation in the tests suggest that binders’ dynamic rheological properties during the long-term aging process may be reliably predicted through laboratory tests. This is conditioned on the binders having been artificially aged to pass the ‘spurt’ reaction stage and data points being collected from the ‘steady’ reaction stage under more ‘natural’ aging conditions. To predict asphalt binder aging in field pavements, additional research is needed to consider the influences of asphalt mixtures.

Invited review: Low milk somatic cell count and susceptibility to mastitis

An enduring controversy exists about low milk cell counts and susceptibility to mastitis. The concentration of milk leukocytes, or somatic cell count (SCC), is a well-established direct indicator of mammary gland inflammation that is highly correlated with the presence of a mammary infection. The SCC is also used as a trait for the selection of dairy ruminants less prone to mastitis. As selection programs favor animals with less SCC, and as milk cells contribute to the defense of the mammary gland, the idea that susceptibility to mastitis could possibly be increased in the long term has been put forward and is still widely debated. Epidemiological and experimental studies aimed at relating SCC to susceptibility to mastitis have yielded results that seem contradictory at first sight. Nevertheless, by taking into account the immunobiology of milk and mammary tissue cells and their role in the defense against infection, along with recent studies on SCC-based divergent selection of animals, the issue can be settled. Apparent SCC-linked susceptibility to mastitis is a phenotypic trait that may be linked to immunomodulation but not to selection.

Multi-frequency Electromagnetic Induction Survey for Archaeological Prospection: Approach and Results in Han Hangu Pass and Xishan Yang in China

This study presents the potential of multi-frequency electromagnetic induction (EMI) in archaeology. EMI is currently less employed for archaeological prospection with respect to other geophysical techniques. It is capable of identifying shallow subsurface relics by simultaneously measuring the apparent electrical conductivity (ECa) and apparent magnetic susceptibility (MSa). Moreover, frequency sounding is able to quantify the depths and vertical shapes of buried structures. In this study, EMI surveys with five frequencies were performed at two heritage sites with different geological conditions: Han Hangu Pass characterized by cinnamon soil and Xishan Yang by sandy loams. In the first site, high ECa values were observed with variations in depth correlated to archaeological remains. Moreover, electromagnetic anomalies related to an ancient road and five kiln caves were identified. In the second site, an ancient tomb, indicating extremely low ECa and high MSa, was discovered. Its electromagnetic properties are attributed to the cavity and ferroferric oxides.

Quantification of liver iron concentration using the apparent susceptibility of hepatic vessels.

The quantification of liver iron concentration (LIC) is important for the monitoring of the body iron level in patients with iron overload. Conventionally, LIC is quantified through R2 or R2* mapping using MRI. In this paper, we demonstrate an alternative approach for LIC quantification through measuring the apparent susceptibility of hepatic vessels using quantitative susceptibility mapping (QSM). QSM was performed in the liver region with the iterative susceptibility weighted imaging and mapping (iSWIM) algorithm, using the geometry of the vessels extracted from magnitude images as constraints. The susceptibilities of liver tissue were estimated from the apparent susceptibility of the hepatic veins and then converted to LIC. The accuracy of the proposed method was first validated using simulations, and then confirmed using in vivo data collected on 8 healthy controls and 11 patients at 3T. The effects of data acquisition parameters were studied using simulations, and the LICs estimated using QSM were compared with those estimated using R2* mapping. Simulation results showed that the use of a 3D data acquisition protocol with higher image resolution led to improved accuracy in LIC quantification using QSM. Both simulations and in vivo data results demonstrated that the LICs estimated using the proposed QSM method agreed well with those estimated using R2* mapping. With the shortest echo time being 2.5ms in the multi-echo gradient echo sequence, simulations results showed that LIC up to 12.45 mg iron/g dry tissue can be quantified using the proposed QSM method. For the in vivo data, the highest LIC measured was 11.32 mg iron/g dry tissue. The proposed method offers a reliable and flexible way to quantify LIC and has the potential to extend the range of LIC that can be accurately measured using R2* and QSM.

Effect of Thermal Aging on the Intergranular Stress Corrosion Cracking Susceptibility of Type 310S Stainless Steel

The effect of thermal aging on the intergranular stress corrosion cracking (IGSCC) susceptibility of Type 310S stainless steel was investigated. Samples were solution-annealed (baseline), sensitized (short-term aging), and thermally-treated (long-term aging) to form Cr-rich M23C6 carbides and sigma (σ) phase precipitate particles, respectively, on the grain boundaries. The thermal-aging heat treatments represent two limiting exposure conditions expected in-service for a fuel cladding in the Canadian Generation IV (supercritical water-cooled reactor) design concept and were considered to better understand the risk factors associated with an in-service IGSCC damage mode. The sensitized treatment exhibited the highest relative degree of sensitization (measured by double loop electrochemical potentiokinetic reactivation testing in 2 M H2SO4 + 0.01 M KSCN) and IGSCC susceptibility (measured by slow strain rate testing [SSRT] in a hot alkaline solution). The relative susceptibility reflects the controlling role played by Cr-depleted zones, which were only observed in the sensitized (short-term aging) material. The relatively large σ phase grain boundary particles in the thermally-treated (long-term aging) material preferentially cracked during SSRT, suggesting an apparent IGSCC susceptibility at the sample surface. However, the absence of Cr-depleted zones in this material prevented IGSCC from occurring, despite preferential cracking in the σ phase grain boundary particles. The dominant fracture mode in the hot alkaline solution was transgranular mixed-mode cracking. The implications of the results are discussed within the context of risk factors associated with an in-service IGSCC susceptibility in supercritical water.

Susceptibility weighted imaging and quantitative susceptibility mapping of the cerebral vasculature using ferumoxytol.

To demonstrate the potential of imaging cerebral arteries and veins with ferumoxytol using susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM). The relationships between ferumoxytol concentration and the apparent susceptibility at 1.5T, 3T, and 7T were determined using phantom data; the ability of visualizing subvoxel vessels was evaluated using simulations; and the feasibility of using ferumoxytol to enhance the visibility of small vessels was confirmed in three healthy volunteers at 7T(with doses 1 mg/kg to 4 mg/kg). The visualization of the lenticulostriate arteries and the medullary veins was assessed by two raters and the contrast-to-noise ratios (CNRs) of these vessels were measured. The relationship between ferumoxytol concentration and susceptibility was linear with a slope 13.3 ± 0.2 ppm·mg-1 ·mL at 7T. Simulations showed that SWI data with an increased dose of ferumoxytol, higher echo time (TE), and higher imaging resolution improved the detection of smaller vessels. With 4 mg/kg ferumoxytol, voxel aspect ratio = 1:8, TE = 10 ms, the diameter of the smallest detectable artery was approximately 50μm. The rating score for arteries was improved from 1.5 ± 0.5 (precontrast) to 3.0 ± 0.0 (post-4 mg/kg) in the in vivo data and the apparent susceptibilities of the arteries (0.65 ± 0.02 ppm at 4 mg/kg) agreed well with the expected susceptibility (0.71 ± 0.05 ppm). The CNR for cerebral vessels with ferumoxytol can be enhanced using SWI, and the apparent susceptibilities of the arteries can be reliably quantified using QSM. This approach improves the imaging of the entire vascular system outside the capillaries and may be valuable for a variety of neurodegenerative diseases which involve the microvasculature. 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:621-633.

Joint Inversion of Apparent Conductivity and Magnetic Susceptibility to Characterize Buried Targets

A good knowledge of the underground space is needed in urban planning. The main objects found buried are water and sewage pipes, cables, and contaminants storage tanks. Through the inversion of inductive electromagnetic data, we can obtain parameters like depth, position, and radius of these targets. Here, we show a joint inversion approach of apparent conductivity and magnetic susceptibility using data collected at the IAG/USP test site. The model employed assumes three coils (transmitter, receiver, and target/conductor) and relates the electromotive force, through the mutual inductance that occurs between the pairs of transmitter–receiver and conductor–receiver coils, to the acquired conductivity and susceptibility data. The achieved adjustment between field and calculated data indicates that, despite the simplicity of the model, it is a good representation of the conductors, increasing the results of the inversion process. The inversion algorithm is based on the controlled random search algorithm, which presented to be quite stable with electromagnetic data. The main advantage of the proposed approach is the relatively fast inversion process that showed better results than the traditional qualitative interpretation usually applied to this kind of investigation, being promising for noninvasive target characterization and having application in geotechnical studies.

The role of genetic polymorphism of β3-adrenergic receptor in the susceptibility to diabetes and its related disorders: a case–control study on Egyptian population

Background The β3-adrenergic receptor (β3-AR) is mainly expressed in adipose tissue and plays an important role in lipid metabolism and metabolic rate by mediating lipolysis and thermogenesis. It has been suggested that the Trp64Arg (T→C) polymorphism in the β3-AR gene affects fat accumulation and/or impairment of lipid and carbohydrate metabolism. Objective The aim of this study was to investigate whether common polymorphism (Trp64Arg) of β3-AR gene has a role in the apparent susceptibility to type 2 diabetes mellitus (DM) and its related disorders in the Egyptian population. Patients and methods One hundred and thirty five healthy controls and 123 individuals with type 2 DM were enrolled in the study. The β3-AR Trp64Arg polymorphism was identified using restriction fragment length polymorphism PCR of peripheral blood DNA samples. Analysis of data was performed using SPSS program 11. Results Allele frequency for C was 23.2% in the diabetic group compared with 12.2% in the control group. The carriers of XC genotype (TC and CC) were at high risk of developing type 2 DM (odds ratio=2.8; 95% confidence interval=1.6–4.9) when compared with the carrier of TT genotype. Furthermore, they were at much higher risk of developing its related disorders such as central obesity, dyslipidemia, and hypertension (odds ratio=2.8; 1.8, 1.5, 2.2, and 2.7 for BMI, waist–hip ratio, triglycerides, high-density lipoprotein, and hypertension, respectively). Conclusion The prevalence of Arg64 allele of the Trp64Arg polymorphism in the β3-AR gene is a risk factor for type 2 DM and its related disorders in the Egyptian population.

Continuous hydrogen production from enzymatic hydrolysate of Agave tequilana bagasse: Effect of the organic loading rate and reactor configuration

Lignocellulosic biomass is a promising alternative energy source, which after pretreatment can be efficiently used as feedstock for biological production of second generation biofuels. Hydrogen is considered an ideal biofuel and its production through dark fermentation has been recognized as a sustainable process. However, more studies with continuous systems are needed for its application at industrial scale. In this study, enzymatic hydrolysate of Agave tequilana bagasse was used for long-term continuous hydrogen production in both, a continuous stirred tank reactor (CSTR) and a trickling bed reactor (TBR), which were operated up to 87days under different organic loading rates (OLR) ranging from 17 to 60gCOD/L-d. Volumetric hydrogen production rate (VHPR) and hydrogen molar yield (HMY) in CSTR displayed an inverse correlation with maximum values of 2.53LH2/L-d and 1.35molH2/mol substrate, attained at OLR 52.2 and 40.2gCOD/L-d, respectively. In contrast, increasing OLR up to 52.9gCOD/L-d simultaneously enhanced VHPR and HMY in TBR, attaining values of 3.45LH2/L-d and 1.53molH2/molsubstrate, respectively. Acetate and butyrate were the main metabolites in both reactors, while lactate and propionate were detected in minor concentrations. Metabolites distribution, electron balances and hydrogen production trends obtained from both reactors suggest that CSTR may be more susceptible to inhibition by hydrogen accumulation than TBR. Apparent hydrogen consumption and susceptibility to high solids load were found to limit further OLR increments in CSTR and TBR, respectively.

Temperature-dependent hysteresis effects on EM induction instruments: An example of single-frequency multi-coil array instruments

Non-invasive electromagnetic (EM) induction has been used in agriculture, earth science and archaeology. This is because the apparent electrical conductivity (ECa or quadrature response – mSm−1) and the apparent magnetic susceptibility (in-phase response – ppt) which they measure are related to soil properties such as clay, soil mineralogy, salinity and soil moisture as well as buried metal objects. Although the accuracy issues of the single-coil array EM38 meter have been widely discussed, the accuracy issues of the next generation, multi-coil (perpendicular-PRP and horizontal-HCP) array DUALEM meter, particularly the instrument drift, have little been reported. In this study, the diurnal drifts of a DUALEM-421S and a DUALEM-21S were studied at single locations (for a 24h period) and along a 480-m transect (at five typical operation times). Based on the experiment results of the two DUALEM instruments, it was found that the ECa readings of the PRP arrays were more stable than those of the HCP arrays. The reverse was true for in-phase measurements. Specifically, during the diurnal cooling and heating phases, ECa measurements of the HCP arrays and in-phase PRP arrays showed different correlations with ambient temperature, which can be defined as instrument-specific and temperature-dependent hysteresis effects. In addition, the stability of ECa and in-phase measurements increased with array length and was much less compared to the theoretical values. It was suggested a similar experiment should be conducted for the DUALEM instruments before the DUALEM surveys and repeated DUALEM surveys for mapping the spatio-temporal variations in soil properties should be carried out at the similar temperature (i.e., similar ambient temperature and within the same warming or cooling phase). In addition, shading the instruments with non-conductive thermal insulation should be adopted and drift correction procedures should be applied to improve the quality of the measurements of the EM instruments.

Costs of reproduction and carry-over effects in breeding albatrosses

AbstractWe investigated the physiology of two closely related albatross species relative to their breeding strategy: black-browed albatrosses (Thalassarche melanophris) breed annually, while grey-headed albatrosses (T. chrysostoma) breed biennially. From observations of breeding fate and blood samples collected at the end of breeding in one season and feather corticosterone levels (fCort) sampled at the beginning of the next breeding season, we found that in both species some post-breeding physiological parameters differed according to breeding outcome (successful, failed, deferred). Correlations between post-breeding physiology and fCort, and links to future breeding decisions, were examined. In black-browed albatrosses, post-breeding physiology and fCort were not significantly correlated, but fCort independently predicted breeding decision the next year, which we interpret as a possible migratory carry-over effect. In grey-headed albatrosses, post-breeding triglyceride levels were negatively correlated with fCort, but only in females, which we interpret as a potential cost of reproduction. However, this potential cost did not carry-over to future breeding in the grey-headed albatrosses. None of the variables predicted future breeding decisions. We suggest that biennial breeding in the grey-headed albatrosses may have evolved as a strategy to buffer against the apparent susceptibility of females to negative physiological costs of reproduction. Future studies are needed to confirm this.

Magnetic and Gravity Gradiometry Framework for Mesoproterozoic Iron Oxide-Apatite and Iron Oxide-Copper-Gold Deposits, Southeast Missouri

High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three-dimensional models, an extensive statistical summary of density and apparent magnetic susceptibility measurements is presented that includes data on several hundred samples taken from the deposits, altered wall rocks, and unaltered country rocks.