Higher Breakdown Rate Research Articles

An N - policy M/M/1 queueing model for energy saving mechanism in Networks

The conservation of power in wireless sensor networks (WSNs) is critical due to the difficulty of replacing or recharging batteries in remote sensor nodes. Additionally, sensor node failure is inevitable in WSNs. In order to overcome these difficulties, this study proposes an N-policy M/M/1 queuing system model with an unstable server. This model offers insightful information for improving performance, maximizing energy use, and prolonging the lifespan of WSNs. The study looks into how different parameters and N-values affect the system's performance by examining the average system size under various scenarios. Important performance parameters are taken into consideration in the suggested model, including the total system size and the average number of data packets in the busy, idle, and down stages. These measurements aid in the comprehension of the behavior of the system and direct the N-policy optimization process to reduce setup, holding, server downtime, and operating state expenses. The analytical results are supported by numerical representations that show system size is reduced by higher repair and service rates and increased by higher breakdown rates. The cost function is estimated using MATLAB simulations, which also find the ideal N-value to reduce the overall predicted cost per unit of time. The findings demonstrate that an ideal N-policy can greatly enhance system performance and energy efficiency, guaranteeing the WSN functions well even in the face of node failure and power limitations. Based on in-depth numerical analysis and performance evaluation, this paper offers a thorough framework for improving WSN efficiency and reliability through strategic N-policy implementation.

Statistics of vacuum electrical breakdown clustering and the induction of follow-up breakdowns

Understanding the underlying physics of vacuum electrical breakdown is of relevance for the development of technologies where breakdown is of significance, either as an intended part of device operation or as a cause of failure. One prominent contemporary case of the latter is high-gradient linear accelerators, where structures must be able to operate with both high surface electric fields and low breakdown rates. Temporal clustering of breakdowns has for long been observed in accelerating structures. In this work, the statistics of breakdown clustering were studied using data collected by a system applying DC voltage pulses over parallel disk electrodes in a vacuum chamber. It was found that the obtained distributions of cluster sizes can be explained by postulating that every breakdown induces a number of follow-up breakdowns that are Poisson-distributed with λ < 1. It was also found that the primary breakdown rate, i.e., the breakdown rate after discounting follow-up breakdowns, fluctuates over time but has no discernible correlation with cluster size. Considered together, these results provide empirical support for the interpretation that primary and follow-up breakdowns are categorically different kinds of events with different underlying causes and mechanisms. Furthermore, they support the interpretation that there is an actual causal relationship between the breakdowns in a cluster rather than them simply being concurrent events with a common underlying cause.

Restart behavior of gelled waxy crude oil pipeline based on an elasto-viscoplastic thixotropic model: A numerical study

Restart of gelled waxy crude oil pipeline is one of the major flow assurance concern in petroleum production. Reliable representation of rheological behavior of gelled waxy crude oil serves as the basis for pipeline restart analysis and modeling. In this work, the Dullaert-Mewis elasto-viscoplastic thixotropic model was modified and applied to improve the representation of the rheology of gelled waxy. Numerical analyses were conducted to evaluate the effects of compressibility, Reynolds number, yield stress number and structural breakdown rate of gelled waxy crude oil on pipeline restart. Combined with rheological experiment data, the effect of viscoelasticity of gelled waxy crude oil on pipeline restart was analyzed. The results suggest that with increasing compressibility of gelled waxy crude oil, the speed of propagation of yield front during restart decreases, the total restart time and steady-state velocity increase and the minimum required pressure difference for successful restart decreases. Low Reynolds number, high yield stress number and low structural breakdown rate lead to high minimum required pressure difference for successful restart and prolonged total restart time. It was also observed that the modified Dullaert-Mewis elasto-viscoplastic thixotropic model provides more optimistic restart assessments, characterized by lower minimum required pressure difference, higher steady-state velocity and shorter total restart time, compared with assessments with a viscoplastic thixotropic model.

Effects of particulate matter (PM2.5) and associated acidity on ecosystem functioning: response of leaf litter breakdown.

Particulate matter (PM2.5 with the diameter ≤ 2.5μm) as one of the most harmful and complex pollutants can reduce environment quality and affect human health. Through acidification by wet deposition, PM2.5 can cause acid rain to impact aquatic ecosystems. However, our understanding of PM2.5 effect on ecosystem functioning is highly limited. This study investigated the relationship between PM2.5 concentration, associated acidity, and leaf litter breakdown of three tree species in laboratory experimental mesocosms, which are weeping willow (Salix babylonica), camphor tree(Cinnamomum camphora), and the south magnolia (Magnolia grandiflora). We found that leaf litter breakdown was significant affected by PM2.5 and associated acidity. With the increase of acidity, the leaf breakdown rate of all three tree species decreased. With the increase of PM2.5 concentration, the leaf breakdown rates of those leaves slowed down. When considering the influence of leaf toughness, willow leaves with lower toughness had a higher breakdown rate than that of camphor tree and the south magnolia. Our study suggests that PM2.5 has significant impact on the aquatic ecosystem functioning through increasing acidification in aquatic environment. Hence, along with ecological restoration of local aquatic habitats, further freshwater ecosystem management should include reducing air pollution through regional efforts of best ecosystem management.

Evaluating the effect of macroinvertebrate exclusion on leaf breakdown rates in two upland Colombian streams

Macroinvertebrate shredders have been widely recognized as an important functional feeding group that contributes to leaf decomposition in temperate streams, but little is known about their role in upland Neotropical streams. In this study, we investigated the effect of macroinvertebrate exclusion on leaf breakdown rates in two upland streams (Marianela and Peña Bonita with 1 911 and 2 560 m elevation, respectively) in Colombia. We hypothesized that leaf litter breakdown is mediated mainly by macroinvertebrate shredders in Colombian upland streams. The study was carried out between January and April of 2009, including the dry season and the beginning of the wet season. We measured leaf mass loss using coarse- (15 mm; accessible to macroinvertebrates) and fine- (200 µm; macroinvertebrates excluded) mesh litter bags that were anchored with wood stakes to the bottom of each stream and recovered after 7, 14, 21, 28, and 56 days. We selected leaves from two dominant plant species and used three leaf treatments: two single species (Palicourea cuatrecasasii and Critoniopsis ursicola) and mixed-species (P. cuatrecasasii and C. ursicola). We compared leaf breakdown rates between the Peña Bonita and Marianela stream, mesh-sizes, and leaf treatments. Macroinvertebrates that colonized the litter bags were measured for density and biomass and categorized in functional feeding groups. In general, there were no significant differences in breakdown rates between the streams and the mesh-sizes. In contrast, leaf breakdown rates had significant differences between all leaf species, where C. ursicola had higher breakdown rates than mixed-species, and P. cuatrecasasii. Macroinvertebrate exclusion did not affect leaf breakdown rates and their assemblages were composed by high densities of collectors (mainly Chironomidae) and few shredders with a large body size. The similar macroinvertebrate colonization between leaf species, the relatively slow breakdown rates, and the shredder scarcity, suggest that leaves were a refractory substrate. Further studies should include leaf species with different nutritional qualities and larger spatial-temporal scales to test the hypothesis of shredder presence and its role on leaf decomposition in upland Colombian streams.

CONSTRUCTION OF SUBHORIZONTAL WELLS IN THE ACHIMOV DEPOSITS

Construction of subhorizontal wells in the Achimov deposits. Panikarovski V. V., Panikarovski E. V. In the article reviews the problems that occur in drilling of subhorizontal wells in Achimov deposits. The analysis is made of fractured-cavernous reservoirs development technologies using the water-base mud solutions which do not ensure the qualitative stripping of productive strata and cause a high breakdown rate at implementing drilling operations. It is proved that the hydrocarbon-base solutions are the most perspective solutions for drilling of subhorizontal wells in such conditions.

Procesado de hojarasca en arroyos del Parque Nacional de la Sierra de Guadarrama (Madrid)

Le af litter breakdown in streams of Sierra de Guadarrama National Park (Madrid) The main goal of this study was to identify the main drivers of natural variability of leaf litter processing in six well preserved Mediterranean mountain streams in the Sierra de Guadarrama, through the analysis of the breakdown rates of alder litter, content and dynamics of leaf nutrients, and associated fungal and invertebrates communities. In general, breakdown rates of alder leaves, both exponential (k = 0.013± 0.005 dd –1 , k ′ = 0.041± 0.011 d –1 ) and lineal (b = 0.470± 0.121% PSLC dd –1 , b ′ = 1.522± 0.153% PSLC d –1 ) were very high. Variability in breakdown rates among streams was not correlated to environmental characteristics (discharge, slope or water temperature) neither to stream water characteristics (nutrient concentration, pH, or conductivity). This may be due to the low environmental heterogeneity observed among these streams and also because the physical factors that could regulate this process were outweighed by biological processes that mask them. The highest breakdown rates were recorded in the coldest waters where the activity of decomposers aquatic fungi was very low (measured by sporulation rates, 98.36±148.84 conidia mg –1 PSLC d –1 ), suggesting that consumer invertebrates played a key role in the faster leaf litter processing rates in these sites. Family richness (13.67±3.44 fam. bag –1 ) and macroinvertebrate density (25.33±10.42 ind bag –1 ), as well as shredder density (16.17±7.44 ind bag –1 ) did not show any relationship with the breakdown rates (p> 0.100, neither linear nor exponential rates). A positive relationship was only found between percentage of leaf litter lost and abundance of Limnephilidae (p< 0.010), that pointed out a higher relevance of shredder traits than their total abundance. Limnephilidae are caddisfly shredders adapted to low thermal regimes, they have large body and are able to feed on unconditioned litter debris and poor colonized by aquatic hyphomycetes, which seem to exert a decisive control over leaf litter processing rate in this type of aquatic ecosystems. Therefore, we can suppose that in colder headwater mountain streams consumer macroinvertebrates (shredders) might have a major relevance in the processing of litter debris whereas decomposers (aquatic hyphomycetes) would play an increasing role in warmer streams.

Low yield of residual vulvar carcinoma and dysplasia upon re-excision for close or positive margins

ObjectivesThe objectives of this study are to determine the utility of re-excision after a primary diagnosis of vulvar carcinoma by assessing the frequency of residual carcinoma found upon re-excision and to quantitate the wound breakdown and carcinoma recurrence rates. MethodsWe reviewed 1122 cases of VIN or vulvar carcinoma. Women who underwent re-excisional procedures, as part of their initial surgical treatment were identified. Associations between the margin status of the original excisional sample and histology of re-excision, as well as association between the depth of invasion upon initial excision and histology of re-excision were analyzed with Chi-square tests. ResultsWe identified 84 evaluable patients, 72 with stage I disease, 4 with stage II, and 7 with stage III disease. Upon the initial excisional procedure, 33 patients (39%) had carcinoma-positive margins, 27 patients had VIN-positive margins (32%) and 24 patients (28%) had negative margins (>1mm). Upon re-excision, 1/24 (4%) patients with negative margins, 2/27 (7%) patients with VIN-positive margins, and 11/33 (33%) patients with carcinoma-positive margins were found to have carcinoma in the re-excision specimens (p<0.0001, χ2=31). Deeper tumor invasion of the initial excisional specimen (1–12mm) was associated with a higher chance of finding carcinoma upon re-excision (range 18–42%, depending on depth of invasion) (p=0.015, χ2=19). Nineteen patients (23%) had vulvar wound breakdown post re-excision. Twelve patients (15%) experienced recurrences. ConclusionsThe yield of micro- or invasive carcinoma at re-excision is low, with a high wound breakdown rate. Re-excision should be considered for patients with margins positive for carcinoma, especially for women with deep invasion, while women with VIN or close but clear margins may be followed.

On the sensitivity of terahertz gyrotron based systems for remote detection of concealed radioactive materials

This paper analyzes some features of systems intended to remotely detect concealed radioactive materials by using a focused THz radiation. This concept is based on possibility to focus high-power THz radiation in a small spot where the wave field exceeds the breakdown threshold. However, in the absence of any sources of ionization, the probability to have in this breakdown-prone volume any seed electrons is very low. Thus, high breakdown rate in a series of THz pulses will indicate the presence of concealed radioactive materials in the vicinity of a focused wave beam. The goal of the present paper is to determine by using the statistical theory THz pulse duration required for reliable initiation of the discharge. Then, the detectable mass of the radioactive material is determined as the function of distance and of the THz wave power and pulse duration. Lastly, possible benefits from using pulse compressors, which shorten the pulse duration but increase the wave power and, hence, the breakdown-prone volume, are analyzed. It is shown that the use of pulse compressors can significantly improve the sensitivity of THz gyrotron based systems for remote detection of concealed radioactive materials.

Amino Acid Metabolism in the Human Fetus at Term: Leucine, Valine, and Methionine Kinetics

Human fetal metabolism is largely unexplored. Understanding how a healthy fetus achieves its fast growth rates could eventually play a pivotal role in improving future nutritional strategies for premature infants. To quantify specific fetal amino acid kinetics, eight healthy pregnant women received before elective cesarean section at term, continuous stable isotope infusions of the essential amino acids [1-13C,15N]leucine, [U-13C5]valine, and [1-13C]methionine. Umbilical blood was collected after birth and analyzed for enrichments and concentrations using mass spectrometry techniques. Fetuses showed considerable leucine, valine, and methionine uptake and high turnover rates. α-Ketoisocaproate, but not α-ketoisovalerate (the leucine and valine ketoacids, respectively), was transported at net rate from the fetus to the placenta. Especially, leucine and valine data suggested high oxidation rates, up to half of net uptake. This was supported by relatively low α-ketoisocaproate reamination rates to leucine. Our data suggest high protein breakdown and synthesis rates, comparable with, or even slightly higher than in premature infants. The relatively large uptakes of total leucine and valine carbon also suggest high fetal oxidation rates of these essential branched chain amino acids.

X-band photonic band-gap accelerator structure breakdown experiment

In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at $X$ band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of $65\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above $110\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of $100\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ and a surface magnetic field of $890\text{ }\text{ }\mathrm{kA}/\mathrm{m}$. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric field effects. These PBG structure results highlight the unexpected role of magnetic fields in breakdown. The hypothesis is presented that the moderate level electric field on the inner rods, about $14\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, is enhanced at small tips and projections caused by pulsed heating, leading to breakdown. Future PBG structures should be built to minimize pulsed surface heating and temperature rise.

Explaining Democratic Survival Globally (1946–2002)

Do parliamentary regimes outperform presidential ones in reducing democratic breakdown? Given the relatively higher breakdown rate of presidential regimes as compared to that of parliamentary regimes, which factors can explain the breakdown of presidential democracies? Using an original global dataset covering 85 countries from 1946 to 2002, this study shows presidential democracies are not intrinsically more likely to collapse than parliamentary ones. The study also reveals the oft-cited “military legacy” cannot explain breakdowns of presidential democracies. Instead, a less effective legislature and unfavorable U.S. foreign policy, two neglected factors in the extant literature, can robustly explain the breakdown of presidential democracies. This research confirms more effective legislatures are more likely to achieve oversight of the military and reduce the latter's threats to democratic survival than less effective legislatures. A test for simultaneity bias indicates the type of political regime does ...

Positive net movements of amino acids in the hindlimb after overnight food deprivation contribute to sustaining the elevated anabolism of neonatal pigs

During the neonatal period, high protein breakdown rate is a metabolic process inherent to elevated rates of protein accretion in skeletal muscle. To determine the relationship between hindlimb net movements of essential and nonessential amino acids in the regulation of hindlimb protein breakdown during an overnight fasting-feeding cycle, we infused overnight-food-deprived 10- and 28-day-old piglets with [1-(13)C]phenylalanine and [ring-(2)H(4)]tyrosine over 7 h (during 3 h of fasting and then during 4 h of feeding). Extraction rates for aspartate and glutamate after an overnight fast were 15% and 51% in the 10-day-old compared with 6% and 25% in the 28-day-old (P < 0.05) piglets, suggesting an altered requirement for precursors of amino acids to shuttle nitrogen to the liver as early life progresses. This occurred simultaneously with marginal positive hindlimb net balance of essential amino acids after an overnight fast, with negative net release of many nonessential amino acids, such as alanine, asparagine, glutamine, glycine, and proline. This suggests that newborn muscle does not undergo significant protein mobilization after a short period of fasting in support of an elevated rate of protein accretion. Furthermore, tyrosine efflux from hindlimb breakdown between overnight fasting and feeding periods was not different in the 10-day-old piglets, for which tyrosine was limiting, but when tyrosine supply balanced requirements in the 28-day-old piglet, hindlimb efflux was increased (P = 0.01). The results of the present study indicate that proteolysis and net movements of amino acids are coordinated mechanisms that sustain the elevated rate of net protein accretion during overnight feeding-fasting cycles in the neonate.

Working Hard to Resist a 'Bad Mother' Label

Drawing upon interview data from a study investigating the experiences of 20 non-resident mothers in the UK, this article explores the narratives of two participants, one who volunteered to become the non-resident parent and one who lost residence against her will. The central focus of the article is concerned with participants' discursive management of their atypical situation. Specific attention is paid to the different ways in which these women presented their situations and how they positioned themselves in relation to dominant cultural scripts surrounding motherhood. It is argued that non-resident mothers are at risk of isolation as a consequence of social stigma and this may pose barriers to their taking a full and active part in the lives of their children. Suggestions are made whereby social workers might play a useful role in facilitating and supporting non-resident mothers within their locality. The issues raised have relevance for other western jurisdictions operating within a framework of gender-neutral family policy because, the number of non-resident mothers can be expected to rise in line with high family breakdown and divorce rates.

Effects of nutrient enrichment on boreal streams: invertebrates, fungi and leaf‐litter breakdown

Summary1. The effect of nutrient enrichment on structural (invertebrate indices) and functional (leaf‐litter breakdown rates) characteristics of stream integrity was studied in nine boreal streams.2. The results showed predicted changes in biotic indices and leaf‐litter breakdown along a complex (principal component) nutrient gradient. Biotic indices were better correlated with nutrient effects than leaf‐litter breakdown.3. Fungal biomass and invertebrate densities in the litter bags were positively correlated with leaf‐litter breakdown, and both were also positively related to the nutrient gradient.4. Invertebrate community composition influenced breakdown rate. High breakdown rates at one site were associated with the high abundance of the detritivore Asellus aquaticus.5. This study lends support to the importance of invertebrate and fungi as mediators of leaf‐litter decomposition. However, our study also shows that study design (length of incubation) can confound the interpretation of nutrient‐induced effects on decomposition.

Assessing effects of eutrophication in streams based on breakdown of eucalypt leaves

Breakdown of eucalypt leaves and the associated communities of invertebrates and fungi were examined in two 2 nd order streams of northwestern Portugal impacted by eucalypt plantations, human settlements and agricultural activities. Breakdown rates of eucalypt leaves were at the upper limit found in streams of the Iberian Peninsula, probably due to high levels of nitrate and phosphate in the stream water. The highest breakdown rates were found in the Guisande River and were associated with high fungal diversity, biomass and sporulation. Also, higher richness in invertebrate taxa and percentage of detritivores occurred in the Guisande River than in the Este River. In the latter stream, fungal biomass and sporulation were depressed, probably because of sedimentation and low current velocity, which could have negatively affected decomposer activity on leaves. Our results suggest that breakdown rates of eucalypt leaves and the associated decomposer communities were sensitive to changes in water quality, supporting the contention that breakdown experiments using poor quality leaf species might be useful for assessing stream integrity.

Evaluation of entropy-based dispatching in flexible manufacturing systems

Traditionally, part dispatching has been done using static rules, rules that fail to take advantage of the dynamic nature of today’s manufacturing systems. In modern manufacturing systems, machines carry multiple tools so parts have the option of being machined at more than one machine. This flexibility, termed routing flexibility in the literature, opens up new possibilities for shop floor planners for the scheduling and dispatching of parts. In this paper, we give some background of manufacturing system flexibility, including its measurements. We also present quantifiable measures of flexibility and discuss part dispatching based on entropic measures of part routing flexibilities. Two rules for parts dispatching, namely ‘least reduction in entropy’ and ‘least relative reduction in entropy’ are presented. It is proposed that to take advantage of system flexibility, parts dispatching rules based on flexibility measures should be used, especially in systems with high breakdown rates. An extensive simulation study is conducted to evaluate the performance of the dispatching rules. The simulation study confirms that entropy-based dispatching rules out-perform traditional dispatching.

Role of fungi, bacteria, and invertebrates in leaf litter breakdown in a polluted river

The effects of water-quality degradation caused by urbanization, agricultural, and industrial activities on leaf litter breakdown and associated communities of invertebrates and microorganisms were examined at 1 reference and 2 downstream polluted sites in the Ave River (northwestern Portugal). Conductivity, concentrations of NH4+-N, NO3−-N, and PO43−-P, and density of culturable microorganisms were high at the polluted sites. Rates of leaf breakdown also were high, and the highest value was found at the most-downstream, nutrient-enriched polluted site. However, the other polluted site had low current velocity and sedimentation, and nutrient enrichment did not lead to rapid leaf breakdown. Shredders were scarce or absent at all sampling sites, and low shredder density probably explained the lack of differences in leaf breakdown rates between fine-mesh and coarse-mesh bags. High fungal and bacterial production on leaves supported high leaf breakdown rates. Bacterial production was greater at both polluted sites than at the reference site, but it did not exceed 11% of the total microbial production. Fungal biomass and production were markedly different between polluted sites, with the highest values corresponding to the fastest leaf breakdown. Our findings indicate that fungi were the major decomposers in this polluted river. We encourage further research on the effects of multiple stressors on the activity of fungal decomposers to help us better understand the mechanisms underlying leaf litter breakdown in streams under stress.

Extracellular Enzyme Activity in the River Elbe during a Spring Flood Event

AbstractThe ecological balance of rivers can be significantly disturbed by floods, increasing the supply of allochthonous material and energy to the fluvial planktonic food web. During spring flooding in the Elbe in 1999, various physicochemical (pH, conductivity, suspended particulate matter (SPM), particulate and dissolved organic carbon (DOC, POC), inorganic nutrients) and biological parameters (concentration of chlorophyll‐a, abundance and biomass of bacteria) were studied in connection with the microbial self‐cleaning capacity (dissolved and particle‐associated extracellular enzyme activity of ten different enzymes). The pattern of dissolved and particulate material was found to differ greatly (regarding dilution and allochthonous input dynamics), with biological parameters displaying partly differing patterns owing to their bioactivity. Hydrolytic activity was detected for all the enzyme categories investigated, with especially high breakdown rates being determined for proteins containing leucine, arginine, and tyrosine. The overall activities of all the microbial extracellular enzymes studied proved to be dominated by the ectoenzymes ((62.8 ± 13.6)%) associated with particulate (particles, aggregates, and bacterial cell walls). The resulting ecological implications for microbial self‐cleaning processes in rivers are discussed.

Dissolved and particulate organic carbon in the southern East China Sea

This work reports distributions of dissolved organic carbon (DOC) and particulate organic carbon (POC) observed along a cross-shelf transect in the southern East China Sea from 1994 to 1996. DOC concentrations were relatively high (>85 μM) in inner shelf and slope waters but low (ca. 65 μM) around the shelf break, where Kuroshio upwelling occurred. Such distribution pattern showed little temporal variations. Colloidal organic carbon (COC), defined as dissolved organic carbon with molecular weight above 1000 Da, was further separated for analysis. Although the coastal water in the inner shelf and the Kuroshio surface water over the slope had similar DOC concentrations, the partitions between COC and the low molecular weight DOC were different. The coastal water contained less COC than the oligotrophic slope water, suggesting a lower production rate and/or a higher breakdown rate in the coastal water. The POC distribution showed a decreasing trend from the inner shelf to the slope with a local maximum at the shelf break, where POC was enriched due to enhanced primary productivity induced by upwelling. The average POC inventory was about 1/10 that of the DOC. A mid-depth maximum was repeatedly observed above the slope, indicating lateral transport of POC offshore from the shelf. The net exports of DOC and POC from the shelf are estimated to be 414 and 106 Gmol C/yr, respectively, but the POC export along the bottom boundary layer is unaccounted for in our assessment.