Volume Anomalies Research Articles

Anomalous thermal properties and spin crossover of ferromagnesite (Mg,Fe) CO3

Ferromagnesite (Mg,Fe)CO3, also referred to as magnesiosiderite at high iron concentration, is a solid solution of magnesite (MgCO3) and siderite (FeCO3). Ferromagnesite is believed to enter the Earth's lower mantle via subduction and is considered a major carbon carrier in the Earth's lower mantle, playing a key role in the Earth's deep carbon cycle. Experiments have shown that ferromagnesite undergoes a pressure-induced spin crossover, accompanied by volume and elastic anomalies, in the lower-mantle pressure range. In this work, we investigate thermal properties of (Mg,Fe)CO3 using first-principles calculations. We show that nearly all thermal properties of ferromagnesite are drastically altered by iron spin crossover, including anomalous reduction of volume, anomalous softening of bulk modulus, and anomalous increases of thermal expansion, heat capacity, and Guneisen parameter. Remarkably, the anomaly of heat capacity remains prominent (up to 40%) at high temperature without smearing out, which suggests that iron spin crossover may significantly affect the thermal properties of subducting slabs and the Earth's deep carbon cycle.

Scoring system in the fetal echogenic kidneys detected during mid trimester anomaly scan

Aim: The present study aimed to evaluate the prognostic scoring system for fetal echogenic kidneys to diagnose the fetal kidney diseases in mid trimester by determining the kidney volume, laterality, bladder size, amniotic fluid and other associated anomalies. Methodology: 27 fetuses diagnosed with the “Echogenic kidneys” were enrolled in the study based on subjective assessment in sonography. The scoring was performed based on the certain parameters including renal size, laterality, bladder size, amniotic fluid and associated anomalies. The prognosis of the live births was assessed during the post natal life. Results: Out of 27 fetuses enrolled in the present study, 11 were live births, 9 were NND, IUD and miscarriage and 7 were terminations. 10 live births had the scoring of 4, 5 and 6 and 1 live birth had a scoring of 8. Conclusion: Within the limitations of the study we can conclude that the scoring system could be a good tool to identify the anomalies in the fetal kidneys during the mid-trimester. With the identification of the fetal echogenic kidneys the prognosis can be ruled out which helps in easing out the parental anxiety and renders them correct advice to opt for termination or not.

Correlations between oceanic crustal thickness, melt volume, and spreading rate from global gravity observation

Oceanic crustal accretion at mid-ocean ridges is a function of spreading rate, mantle temperature, and composition, which are intertwined in affecting melt production and oceanic crustal thickness. Sparse and irregular seismic and geochemical observations on a global scale showed no correlation between crustal thickness and spreading rate along slow to fast-spreading centers. Here, we compile a global oceanic crustal thickness model from gravity data to revisit this issue at a high resolution. Gravity-observed melt volume shows a positive correlation with spreading rate globally, implying that spreading rate is the dominant factor in melt production. However, oceanic crustal thickness is negatively correlated with spreading rate from slow to fast-spreading centers, and this trend is further consolidated by the increase in Curie point depth (a geothermal proxy) and ridge depth with increasing spreading rate. Thus, a decreasing near-ridge temperature probably contributes to crustal thinning from slow to fast-spreading centers. Inferred low melt volume anomalies beneath fast-spreading centers are consistent with a 20 °C temperature drop in the near-ridge mantle, likely caused by efficient hydrothermal cooling.

Activation of cryptic splicing in bovine WDR19 is associated with reduced semen quality and male fertility.

Cattle are ideally suited to investigate the genetics of male reproduction, because semen quality and fertility are recorded for all ejaculates of artificial insemination bulls. We analysed 26,090 ejaculates of 794 Brown Swiss bulls to assess ejaculate volume, sperm concentration, sperm motility, sperm head and tail anomalies and insemination success. The heritability of the six semen traits was between 0 and 0.26. Genome-wide association testing on 607,511 SNPs revealed a QTL on bovine chromosome 6 that was associated with sperm motility (P = 2.5 x 10-27), head (P = 2.0 x 10-44) and tail anomalies (P = 7.2 x 10-49) and insemination success (P = 9.9 x 10-13). The QTL harbors a recessive allele that compromises semen quality and male fertility. We replicated the effect of the QTL on fertility (P = 7.1 x 10-32) in an independent cohort of 2481 Brown Swiss bulls. The analysis of whole-genome sequencing data revealed that a synonymous variant (BTA6:58373887C>T, rs474302732) in WDR19 encoding WD repeat-containing protein 19 was in linkage disequilibrium with the fertility-associated haplotype. WD repeat-containing protein 19 is a constituent of the intraflagellar transport complex that is essential for the physiological function of motile cilia and flagella. Bioinformatic and transcription analyses revealed that the BTA6:58373887 T-allele activates a cryptic exonic splice site that eliminates three evolutionarily conserved amino acids from WDR19. Western blot analysis demonstrated that the BTA6:58373887 T-allele decreases protein expression. We make the remarkable observation that, in spite of negative effects on semen quality and bull fertility, the BTA6:58373887 T-allele has a frequency of 24% in the Brown Swiss population. Our findings are the first to uncover a variant that is associated with quantitative variation in semen quality and male fertility in cattle.

Submesoscale Eddy Vertical Covariances and Dynamical Constraints from High-Resolution Numerical Simulations

AbstractWe analyze high-resolution (1 km) simulations of the western Pacific, Gulf of Mexico, and Arabian Sea to understand submesoscale eddy dynamics. A mask based on the Okubo–Weiss parameter isolates small-scale eddies, and we further classify those with |ζ/f| ≥ 1 as being submesoscale eddies. Cyclonic submesoscale eddies exhibit a vertical depth structure in which temperature anomalies from the large-scale background are negative. Peak density anomalies associated with cyclonic submesoscale eddies are found at a depth approximately twice the mixed layer depth (MLD). Within anticyclonic submesoscale eddies, temperature anomalies are positive and have peak density anomalies at the MLD. The depth–depth covariance structure for the cyclonic and anticyclonic submesoscale eddies have maxima over a shallow region near the surface and weak off diagonal elements. The observed vertical structure suggests that submesoscale eddies have a shallower depth profile and smaller vertical correlation scales when compared to the mesoscale phenomenon. We test a two-dimensional submesoscale eddy dynamical balance. Compared to a geostrophic dynamical balance using only pressure gradient and Coriolis force, including velocity tendency and advection produces lower errors by about 20%. In regions with strong tides and associated internal waves (western Pacific and Arabian Sea), using the mixed layer integrated small-scale steric height within the dynamical equations produces the lowest magnitude errors. In areas with weak tides (Gulf of Mexico), using small-scale sea surface height (SSH) produces the lowest magnitude errors. Recovering a submesoscale eddy with the correct magnitude and rotation requires integration of small-scale specific volume anomalies well below the mixed layer.

Interpolation methods in GPR tomographic imaging of linear and volume anomalies for cultural heritage diagnostics

This paper presents results of a ground penetrating radar (GPR) survey conducted in St. Joseph’s Church in Gdańsk, Poland. The aim of the study was to produce tomographic imaging of a renovated floor as well as the objects buried under the floor to detect linear and volume inclusions. The assumed track spacing was meaningfully greater than the single signal spacing in each track, which induced the need for interpolation methods to estimate signal values in the areas beyond the trace lines. Various interpolation techniques were used to prepare the tomography maps. GPR time slices allowed the identification of reinforcing meshes, underfloor heating system elements and the foundations of entrances to crypts. The results obtained were compared to the exact images acquired in a dense regular grid to evaluate the efficiency of the applied interpolation methods and to verify the possibility of conducting GPR surveys with coarse track spacing.

The effects of aging on semen parameters and sperm DNA fragmentation.

IntroductionThis study aimed to look into possible correlations between male age and different sperm parameters derived from semen analysis and sperm deoxyribonucleic acid (DNA) fragmentation.MethodsThis retrospective descriptive study included 2681 male patients who underwent semen analysis at Clínica Las Condes (CLC), Santiago, Chile, between January 2014 and May 2017; correlations between age and sperm parameters were analyzed.ResultsMales above the age of 50 were significantly more likely to present anomalies in semen volume, sperm concentration, and sperm DNA fragmentation; males aged 41+ years were more likely to have lower sperm concentration levels; males aged 31+ years were more likely to have decreased sperm motility; when concentration was constant, more volume and motility anomalies were seen as age increased; when volume was kept constant, more motility and concentration anomalies were seen as age increased; and when motility was constant, normal semen volumes decreased as age increased.ConclusionOur study showed that male age significantly affects sperm parameters that might have an impact on male fertility.

Statistical and probabilistic analysis of interarrival and waiting times of Internet2 anomalies

Motivated by the need to introduce design improvements to the Internet network to make it robust to high traffic volume anomalies, we analyze statistical properties of the time separation between arrivals of consecutive anomalies in the Internet2 network. Using several statistical techniques, we demonstrate that for all unidirectional links in Internet2, these interarrival times have distributions whose tail probabilities decay like a power law. These heavy-tailed distributions have varying tail indexes, which in some cases imply infinite variance. We establish that the interarrival times can be modeled as independent and identically distributed random variables, and propose a model for their distribution. These findings allow us to use the tools of of renewal theory, which in turn allows us to estimate the distribution of the waiting time for the arrival of the next anomaly. We show that the waiting time is stochastically substantially longer than the time between the arrivals, and may in some cases have infinite expected value. All our findings are tabulated and displayed in the form of suitable graphs, including the relevant density estimates.

Diversified Quality Aware Ensemble Resource Scheduling (DQAERS) for IAAS with Massive Load of Tasks and Resources in Cloud Computing

Identifying a deterministic approach to perform resource scheduling in cloud computing is crucial requirement, which is since, the volume of the anomalies and the high dimensionality of the values projected to these anomalies observed during resource scheduling. The volume of tasks that evinces flash-crowd state at resource broker of the IAAS, and high dimensionality of the anomalies projected for resource quality factors are out of scope in regard to contemporary resource scheduling strategies contributed in recent past. Hence’ the resource scheduling by contemporary methods in such conditions are insignificant as the resource scheduling optimality observed as probabilistic. In order to optimize the resource scheduling in the context of aforesaid properties high volume of tasks (flash-crowd state at resource broker) and high dimensional projection of anomalies, this manuscript derived an ensemble resource scheduling strategy, which fall in to the category of batch scheduling. The experimental study outlined that the proposal is most prominent and robust to deliver optimal resource scheduling in the context of anomalies of high volume and dimensionality that compared to the contemporary method.

Inter-annual variability of shelf water volume on the northeastern Canadian and United States continental shelf, 1973–2013

Understanding the variability of waters confined to the northeastern United States and Canadian continental shelf is essential in determining factors that influence hydrographic patterns and structure, changes in fisheries stocks and planktonic assemblages, and the impact of Arctic warming. Shelf waters (SHW) located between Newfoundland and Cape Hatteras are characterized by lower salinity (<34 PSU) and lower temperatures than the generally warmer and more saline slope waters located farther offshore. Significant inter-annual variability of SHW volume has been noted from previous studies within the more limited Mid Atlantic Bight sub-region. Multiple factors may impact the volume of SHW, including local and remote river runoff and precipitation, release and equator-ward transport of fresh water from the Arctic and sub-polar gyre, ice melt from Greenland, cross-shelf removal, and both vertical and horizontal mixing processes. Here, we estimate inter-annual variability of SHW volume over the large shelf domain located between Newfoundland and Cape Hatteras from 1973 through 2013. Objectively-analyzed (OA) annual mean SHW thickness and error (as a percent of data variance) is computed for each of eleven sub-regions spanning our study domain for the 41-year period. Results show significant decreasing trends in SHW volume within 5 of the 11 sub-regions (The Grand Banks through the Eastern Scotian Shelf sub-regions) in agreement with previous work which has shown a decreasing trend of northern Labrador Current transport. OA annual mean SHW volume anomalies were cross-correlated with annual mean shelf slope front (SSF) position anomalies for corresponding sub-regions, displaying a highly significant relationship for the Georges Bank, the Mid Atlantic Bight, and the DelMarVa Hatteras shelf, with higher volumes corresponding to more offshore SSF positions. Annual mean near-surface salinity anomalies, when cross-correlated with OA annual mean SHW volume anomalies, displayed significant positive correlations from the Gulf of St. Lawrence northeast to the Newfoundland shelf and displayed primarily negative correlations from the Gulf of Maine to the DelMarVa Hatteras sub-region. The North Atlantic Oscillation annual indices displayed significant cross-correlations with annual mean OA SHW volume anomalies only for the Tail of the Grand Banks and Georges Bank., There were no significant cross correlations computed between the OA annual mean SHW volume anomalies and the NAO winter index for corresponding years.

Are Prominent Equity Market Anomalies in India Fading Away?

In this study, we revisit prominent equity market anomalies documented for India, namely size, value, volume and momentum. Using data for NSE 500 companies, we test for the persistence of these anomalies for a recent period from July 2005 to June 2016 employing one-factor capital asset pricing model (CAPM) and three-factor Fama–French model as asset pricing benchmarks. We test for the robustness of these anomalies by (a) forming both quintile and decile portfolios and (b) forming univariate and variety of bivariate-sorted portfolios. Corner portfolios based on deciles provide greater return differentials compared to quintile portfolios. Bivariate-sorted portfolios do not seem to outperform univariate-sorted portfolios. The value and momentum anomalies are explained by risk models which is contrary to prior evidence. Size and volume anomalies continue to provide significant returns but seem to have faded substantially over time when compared with the past results. The findings about weakening prominent Indian equity market anomalies shall pose a challenge for portfolio managers who may have to look for other sources of extra-normal profits. Indian market also seems to be informationally more efficient which is in line with recent financial market reforms and growing emphasis on financial inclusion and corporate governance.

Arctic sea ice thickness, volume, and multiyear ice coverage: losses and coupled variability (1958–2018)

Large-scale changes in Arctic sea ice thickness, volume and multiyear sea ice (MYI) coverage with available measurements from submarine sonars, satellite altimeters (ICESat and CryoSat-2), and satellite scatterometers are summarized. The submarine record spans the period between 1958 and 2000, the satellite altimeter records between 2003 and 2018, and the scatterometer records between 1999 and 2017. Regional changes in ice thickness (since 1958) and within the data release area of the Arctic Ocean, previously reported by Kwok and Rothrock (2009 Geophys. Res. Lett. 36 L15501), have been updated to include the 8 years of CryoSat-2 (CS-2) retrievals. Between the pre-1990 submarine period (1958–1976) and the CS-2 period (2011–2018) the average thickness near the end of the melt season, in six regions, decreased by 2.0 m or some 66% over six decades. Within the data release area (∼38% of the Arctic Ocean) of submarine ice draft, the thinning of ∼1.75 m in winter since 1980 (maximum thickness of 3.64 m in the regression analysis) has not changed significantly; the mean thickness over the CS-2 period is ∼2 m. The 15 year satellite record depicts losses in sea ice volume at 2870 km3/decade and 5130 km3/decade in winter (February–March) and fall (October–November), respectively: more moderate trends compared to the sharp decreases over the ICESat period, where the losses were weighted by record-setting melt in 2007. Over the scatterometer record (1999–2017), the Arctic has lost more than 2 × 106 km2 of MYI—a decrease of more than 50%; MYI now covers less than one-third of the Arctic Ocean. Independent MYI coverage and volume records co-vary in time, the MYI area anomalies explain ∼85% of the variance in the anomalies in Arctic sea ice volume. If losses of MYI continue, Arctic thickness/volume will be controlled by seasonal ice, suggesting that the thickness/volume trends will be more moderate (as seen here) but more sensitive to climate forcing.

Predicting regional and pan-Arctic sea ice anomalies with kernel analog forecasting

Predicting Arctic sea ice extent is a notoriously difficult forecasting problem, even for lead times as short as one month. Motivated by Arctic intraannual variability phenomena such as reemergence of sea surface temperature and sea ice anomalies, we use a prediction approach for sea ice anomalies based on analog forecasting. Traditional analog forecasting relies on identifying a single analog in a historical record, usually by minimizing Euclidean distance, and forming a forecast from the analog's historical trajectory. Here an ensemble of analogs are used to make forecasts, where the ensemble weights are determined by a dynamics-adapted similarity kernel, which takes into account the nonlinear geometry on the underlying data manifold. We apply this method for forecasting pan-Arctic and regional sea ice area and volume anomalies from multi-century climate model data, and in many cases find improvement over the benchmark damped persistence forecast. Examples of success include the 3--6 month lead time prediction of pan-Arctic area, the winter sea ice area prediction of some marginal ice zone seas, and the 3--12 month lead time prediction of sea ice volume anomalies in many central Arctic basins. We discuss possible connections between KAF success and sea ice reemergence, and find KAF to be successful in regions and seasons exhibiting high interannual variability.

Magnetoelectric spin-glass transition(s) in pure and disordered BiFeO3

We present here the results of a comparative study of the spin glass (SG) transition in pure and disordered (0.80BiFeO3-0.20BaTiO3 or 0.80BF-0.20BT) BiFeO3. It is shown that the anomalous frequency dependence of ac susceptibility in the SG phase of BF is not linked with the spin cycloid as it is present even after its destruction in 0.80BF-0.20BT solid solution. Our neutron scattering studies on disordered BF reveal the presence of long-range ordered (LRO) antiferromagnetic (AFM) peak and decrease in the ordered magnetic moment from the overall Brillouin function behaviour around the SG transition suggesting that some spin components are getting detached from the AFM phase. Further, the SG transition is accompanied with anomalies in the unit cell volume and ferroelectric polarization around the SG transition temperature, highlighting the presence of magnetoelastic and magnetoelectric couplings, respectively. All these results suggest that the SG phase of BF is intrinsic to the system and is not due to nano-sized impurities.

Regional grey matter volume correlates of gambling disorder, gambling-related cognitive distortions, and emotion-driven impulsivity

ABSTRACTReports of regional grey matter volume (GMV) anomalies in patients with gambling disorder (PGD) are inconsistent, which can be attributed to methodological disparity and inattention to individual variability. Voxel-based morphometry was used to compare GMV between 25 PGD and 25 healthy controls. Additionally, the study explored associations of interpretative bias (IB, the tendency to reinterpret gambling outcomes) and negative urgency (NU, the tendency to act rashly under negative affect) with GMV in patients. These measures were chosen based on their sound association with gambling disorder in related studies. GMV tests were corrected across the whole brain (using a combination of voxel and cluster-level thresholds for a clusterwise-equivalent p ≤ 0.05). GMV was smaller in PGD than in controls in the dorsomedial prefrontal cortex. In PGD, a stronger cognitive distortion (higher IB) was associated with reduced GMV in the dorsal anterior cingulate; and patients with higher levels of impulsivity (higher NU) presented reduced GMV in the right ventrolateral prefrontal cortex. These findings are consistent with recent studies exploring individual differences in GD. However, the area discriminating between groups showed no overlap with the ones associated with IB and NU. These traits are thus unlikely to be responsible for between-group GMV differences.

Pressure-induced magnetic moment abnormal increase in Mn2FeAl and non-continuing decrease in Fe2MnAl via first principles

The magnetism of Fe2MnAl and Mn2FeAl compounds are studied by first principles. Evolutions of magnetic moment of Fe2MnAl display distinct variation trends under pressure, showing three different slopes at different pressure intervals, 0~100 GPa, 100~250 GPa, 250–400 GPa, respectively, and the moment collapses finally at 450 GPa. The magnetic moment of Mn2FeAl shows an increasing tendency below 40 GPa and decreases subsequently with pressure, and collapses ultimately at about 175 GPa. Such non-continuing decrease of Fe2MnAl originates from the unusual charge transfer of Fe and Mn and bond populations rearrangement of Fe-Fe and Mn-Fe, whereas the distinct moment evolution of Mn2FeAl is attributed to the complicated distributions of bond populations. The half-metallicity of the compounds can be maintained at low pressure, below about 100 GPa in Fe2MnAl and 50 GPa in Mn2FeAl. The magnetic moment collapse process didn’t induce volume and bond length anomalies in the two compounds, the unique anomaly is the elastic softening behaviour in elastic constant c44 and shear (G) and Young’s (E) moduli of Fe2MnAl at 270 GPa, where the second moment collapse occurs.

Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover and fast ice decay

Abstract. Ice retreat in the eastern Eurasian Arctic is a consequence of atmospheric and oceanic processes and regional feedback mechanisms acting on the ice cover, both in winter and summer. A correct representation of these processes in numerical models is important, since it will improve predictions of sea ice anomalies along the Northeast Passage and beyond. In this study, we highlight the importance of winter ice dynamics for local summer sea ice anomalies in thickness, volume and extent. By means of airborne sea ice thickness surveys made over pack ice areas in the south-eastern Laptev Sea, we show that years of offshore-directed sea ice transport have a thinning effect on the late-winter sea ice cover. To confirm the preconditioning effect of enhanced offshore advection in late winter on the summer sea ice cover, we perform a sensitivity study using a numerical model. Results verify that the preconditioning effect plays a bigger role for the regional ice extent. Furthermore, they indicate an increase in volume export from the Laptev Sea as a consequence of enhanced offshore advection, which has far-reaching consequences for the entire Arctic sea ice mass balance. Moreover we show that ice dynamics in winter not only preconditions local summer ice extent, but also accelerate fast-ice decay.

Use of bias correction techniques to improve seasonal forecasts for reservoirs — A case-study in northwestern Mediterranean

In this paper, we have compared different bias correction methodologies to assess whether they could be advantageous for improving the performance of a seasonal prediction model for volume anomalies in the Boadella reservoir (northwestern Mediterranean). The bias correction adjustments have been applied on precipitation and temperature from the European Centre for Middle-range Weather Forecasting System 4 (S4). We have used three bias correction strategies: two linear (mean bias correction, BC, and linear regression, LR) and one non-linear (Model Output Statistics analogs, MOS-analog). The results have been compared with climatology and persistence. The volume-anomaly model is a previously computed Multiple Linear Regression that ingests precipitation, temperature and in-flow anomaly data to simulate monthly volume anomalies. The potential utility for end-users has been assessed using economic value curve areas. We have studied the S4 hindcast period 1981–2010 for each month of the year and up to seven months ahead considering an ensemble of 15 members. We have shown that the MOS-analog and LR bias corrections can improve the original S4. The application to volume anomalies points towards the possibility to introduce bias correction methods as a tool to improve water resource seasonal forecasts in an end-user context of climate services. Particularly, the MOS-analog approach gives generally better results than the other approaches in late autumn and early winter.

Improving Detection of Call Clusters through Surveillance of Poison Center Data

ObjectiveOur objective was to compare the effectiveness of applying thehistorical limits method (HLM) to poison center (PC) call volumeswith vs without stratifying by exposure type.IntroductionThe Centers for Disease Control and Prevention (CDC) uses theNational Poison Data System (NPDS) to conduct surveillance ofcalls to United States PCs. PCs provide triage and treatment advicefor hazardous exposures through a free national hotline. Informationon demographics, health effects, implicated substance(s), medicaloutcome of the patient, and other variables are collected.CDC uses automated algorithms to identify anomalies in both purecall volume and specific clinical effect volume, and to identify callsreporting exposure to high priority agents. Pure and clinical effectvolume anomalies are identified when an hourly call count exceeds athreshold based on historical data using HLM.1Clinical toxicologistsand epidemiologists at the American Association of Poison ControlCenters and CDC apply standardized criteria to determine if theanomaly identifies a potential incident of public health significance(IPHS) and to notify the respective health departments and localPCs as needed. Discussions with NPDS users and analysis of IPHSshowed that alerting based on pure call volume yielded excessivefalse positives. A study using a 5-year NPDS call dataset assessed thepositive predictive value (PPV) of the call volume-based approach.This study showed that less than 4% of anomalies were IPHS.2A low PPV can cause unnecessary waste of staff time and resourcesanalyzing false positive anomalies.As an alternative to pure call volume-based detection where allcalls to each PC are aggregated for anomaly detection, we consideredseparating calls by toxicologically-relevant exposure categories formore targeted anomaly detection. We hypothesized that this stratifiedapproach would reduce the number of false positives.MethodsWe derived our exposure categories based on the criteria that thecategories must: 1) relate to hazardous exposures of public healthimportance, 2) reflect categories based on clinical effects andtreatment modalities, 3) avoid high priority exposures that may betriggered by single calls, 4) be compatible with exposure substanceidentification codes currently used by PCs and NPDS, and 5) includeenough calls for meaningful tracking. We queried all calls reportingexposures to the proposed categories between January 1, 2009and July 31, 2015 for ten PCs. We applied the HLM method afterstratifying by exposure category and tabulated the number of alertstriggered for each category during the study period. We then appliedthe HLM method for the ten PCs on all combined exposure calls torepresent the traditional non-stratified approach. We compared thecombined alert burden generated by stratifying by exposure categorywith the alert burden for the non-stratified approach for varying timewindows (1-, 2-, 4-, 8- and 24-hours). We conducted analysis in R.ResultsWe derived a total of 20 exposure categories, including chemicals(n=4), drugs of abuse (n=6), pesticides (n=3), gas/fume/vapors (n=2),contaminated food/water (n=1), and others (n=4). Call counts during2015 for these categories ranged from approximately 5,000 to 90,000.Table 1 shows the total number of alerts triggered for each methodby time windows. There was a marked reduction of alert burdenwhen first stratifying by exposure category for time windows shorterthan eight hours compared to the alert burden for the non-stratifiedapproach.ConclusionsStratification of call volume by exposure category and timewindow suggests potential improvement over traditional non-stratified approach by having a lower alert burden. Further workshould focus on refining the exposure categories, refining the timewindow for surveillance, and assessing other detection performancemetrics, such as sensitivity.Table 1: Alert burden comparison for the non-stratified vs stratified approach

Summer Enhancement of Arctic Sea Ice Volume Anomalies in the September-Ice Zone

Because of its persistence on seasonal time scales, Arctic sea ice thickness (SIT) is a potential source of predictability for summer sea ice extent (SIE). New satellite observations of SIT represent an opportunity to harness this potential predictability via improved thickness initialization in seasonal forecast systems. In this work, the evolution of Arctic sea ice volume anomalies is studied using a 700-yr control integration and a suite of initialized ensemble forecasts from a fully coupled global climate model. This analysis is focused on the September sea ice zone, as this is the region where thickness anomalies have the potential to impact the SIE minimum. The primary finding of this paper is that, in addition to a general decay with time, sea ice volume anomalies display a summer enhancement, in which anomalies tend to grow between the months of May and July. This summer enhancement is relatively symmetric for positive and negative volume anomalies and peaks in July regardless of the initial month. Analysis of the surface energy budget reveals that the summer volume anomaly enhancement is driven by a positive feedback between the SIT state and the surface albedo. The SIT state affects surface albedo through changes in the sea ice concentration field, melt-onset date, snow coverage, and ice thickness distribution, yielding an anomaly in the total absorbed shortwave radiation between May and August, which enhances the existing SIT anomaly. This phenomenon highlights the crucial importance of accurate SIT initialization and representation of ice–albedo feedback processes in seasonal forecast systems.