Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus

BACKGROUND: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. METHOD: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300 imputed genetic variants in 48,155 cases and 43,612 controls of European descent, 6269 cases and 6624 controls of East Asian descent and 1116 cases and 932 controls of African descent in the Breast Cancer Association Consortium (BCAC; http://bcac.ccge.medschl.cam.ac.uk/ ), and in 15,252 BRCA1 mutation carriers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Stepwise regression analyses were performed to identify independent association signals. Data from the Encyclopedia of DNA Elements project (ENCODE) and the Cancer Genome Atlas (TCGA) were used for functional annotation. RESULTS: Analysis of data from European descendants found evidence for four independent association signals at 12p11, represented by rs7297051 (odds ratio (OR) = 1.09, 95 % confidence interval (CI) = 1.06-1.12; P = 3 × 10(-9)), rs805510 (OR = 1.08, 95 % CI = 1.04-1.12, P = 2 × 10(-5)), and rs1871152 (OR = 1.04, 95 % CI = 1.02-1.06; P = 2 × 10(-4)) identified in the general populations, and rs113824616 (P = 7 × 10(-5)) identified in the meta-analysis of BCAC ER-negative cases and BRCA1 mutation carriers. SNPs rs7297051, rs805510 and rs113824616 were also associated with breast cancer risk at P < 0.05 in East Asians, but none of the associations were statistically significant in African descendants. Multiple candidate functional variants are located in putative enhancer sequences. Chromatin interaction data suggested that PTHLH was the likely target gene of these enhancers. Of the six variants with the strongest evidence of potential functionality, rs11049453 was statistically significantly associated with the expression of PTHLH and its nearby gene CCDC91 at P < 0.05. CONCLUSION: This study identified four independent association signals at 12p11 and revealed potentially functional variants, providing additional insights into the underlying biological mechanism(s) for the association observed between variants at 12p11 and breast cancer risk

Broad-scale patterns of sex ratios in Patella spp.: a comparison of range edge and central range populations in the British Isles and Portugal

Sex change, or sequential hermaphroditism, occurs in the plant and animal kingdoms and often determines a predominance of the first sex. Our aim was to explore changes in sex ratios within the range of the species studied: Patella vulgata and Patella depressa. The broad-scale survey of sex with size of limpets covered a range of latitudes from Zambujeira do Mar (southern Portugal) to the English Channel. Indirect evidence was found for the occurrence of protandry in P. vulgata populations from the south of England, with females predominating in larger size-classes; cumulative frequency distributions of males and females were different; sex ratios were biased towards males and smallest sizes of males were smaller than the smallest sizes of females. In contrast in Portugal females were found in most size-classes of P. vulgata. In P. depressa populations from the south coast of England and Portugal females were interspersed across most size-classes; size distributions of males and females and size at first maturity of males and females did not differ. P. depressa did, however, show some indications of the possibility of slight protandry occurring in Portugal. The test of sex ratio variation with latitude indicated that P. vulgata sex ratios might be involved in determining the species range limit, particularly at the equatorward limit since the likelihood of being male decreased from the south coast of England to southern Portugal. Thus at the southern range limit, sperm could be in short supply due to scarcity of males contributing to an Allee effect.

Broad-scale patterns of sex ratios in Patella spp.: a comparison of range edge and central range populations in the British Isles and Portugal

Sex change, or sequential hermaphroditism, occurs in the plant and animal kingdoms and often determines a predominance of the first sex. Our aim was to explore changes in sex ratios within the range of the species studied: Patella vulgata and Patella depressa. The broad-scale survey of sex with size of limpets covered a range of latitudes from Zambujeira do Mar (southern Portugal) to the English Channel. Indirect evidence was found for the occurrence of protandry in P. vulgata populations from the south of England, with females predominating in larger size-classes; cumulative frequency distributions of males and females were different; sex ratios were biased towards males and smallest sizes of males were smaller than the smallest sizes of females. In contrast in Portugal females were found in most size-classes of P. vulgata. In P. depressa populations from the south coast of England and Portugal females were interspersed across most size-classes; size distributions of males and females and size at first maturity of males and females did not differ. P. depressa did, however, show some indications of the possibility of slight protandry occurring in Portugal. The test of sex ratio variation with latitude indicated that P. vulgata sex ratios might be involved in determining the species range limit, particularly at the equatorward limit since the likelihood of being male decreased from the south coast of England to southern Portugal. Thus at the southern range limit, sperm could be in short supply due to scarcity of males contributing to an Allee effect.

Genome-wide association studies in oesophageal adenocarcinoma and Barrett's oesophagus: a large-scale meta-analysis

Background: Esophageal adenocarcinoma (EA) is one of the fastest rising cancers in western countries. Barrett’s Esophagus (BE) is the premalignant precursor of EA. However, only a subset of BE patients develop EA, which complicates the clinical management in the absence of valid predictors. Genetic risk factors for BE and EA are incompletely understood. This study aimed to identify novel genetic risk factors for BE and EA.Methods: Within an international consortium of groups involved in the genetics of BE/EA, we performed the first meta-analysis of all genome-wide association studies (GWAS) available, involving 6,167 BE patients, 4,112 EA patients, and 17,159 representative controls, all of European ancestry, genotyped on Illumina high-density SNP-arrays, collected from four separate studies within North America, Europe, and Australia. Meta-analysis was conducted using the fixed-effects inverse variance-weighting approach. We used the standard genome-wide significant threshold of 5×10-8 for this study. We also conducted an association analysis following reweighting of loci using an approach that investigates annotation enrichment among the genome-wide significant loci. The entire GWAS-data set was also analyzed using bioinformatics approaches including functional annotation databases as well as gene-based and pathway-based methods in order to identify pathophysiologically relevant cellular pathways.Findings: We identified eight new associated risk loci for BE and EA, within or near the CFTR (rs17451754, P=4·8×10-10), MSRA (rs17749155, P=5·2×10-10), BLK (rs10108511, P=2·1×10-9), KHDRBS2 (rs62423175, P=3·0×10-9), TPPP/CEP72 (rs9918259, P=3·2×10-9), TMOD1 (rs7852462, P=1·5×10-8), SATB2 (rs139606545, P=2·0×10-8), and HTR3C/ABCC5 genes (rs9823696, P=1·6×10-8). A further novel risk locus at LPA (rs12207195, posteriori probability=0·925) was identified after re-weighting using significantly enriched annotations. This study thereby doubled the number of known risk loci. The strongest disease pathways identified (P<10-6) belong to muscle cell differentiation and to mesenchyme development/differentiation, which fit with current pathophysiological BE/EA concepts. To our knowledge, this study identified for the first time an EA-specific association (rs9823696, P=1·6×10-8) near HTR3C/ABCC5 which is independent of BE development (P=0·45).Interpretation: The identified disease loci and pathways reveal new insights into the etiology of BE and EA. Furthermore, the EA-specific association at HTR3C/ABCC5 may constitute a novel genetic marker for the prediction of transition from BE to EA. Mutations in CFTR, one of the new risk loci identified in this study, cause cystic fibrosis (CF), the most common recessive disorder in Europeans. Gastroesophageal reflux (GER) belongs to the phenotypic CF-spectrum and represents the main risk factor for BE/EA. Thus, the CFTR locus may trigger a common GER-mediated pathophysiology.

The large- and small-scale Ca IIK structure of the Milky Way from observations of Galactic and Magellanic sightlines

Aims. The large and small-scale (pc) structure of the Galactic interstellar medium can be investigated by utilising spectra of early-type stellar probes of known distances in the same region of the sky. This paper determines the variation in line strength of Ca ii at 3933.661 Å as a function of probe separation for a large sample of stars, including a number of sightlines in the Magellanic Clouds. 

Methods. FLAMES-GIRAFFE data taken with the Very Large Telescope towards early-type stars in 3 Galactic and 4 Magellanic open clusters in Ca ii are used to obtain the velocity, equivalent width, column density, and line width of interstellar Galactic calcium for a total of 657 stars, of which 443 are Magellanic Cloud sightlines. In each cluster there are between 43 and 111 stars observed. Additionally, FEROS and UVES Ca ii K and Na i D spectra of 21 Galactic and 154 Magellanic early-type stars are presented and combined with data from the literature to study the calcium column density - parallax relationship. 

Results. For the four Magellanic clusters studied with FLAMES, the strength of the Galactic interstellar Ca ii K equivalent width on transverse scales from ∼0.05-9 pc is found to vary by factors of ∼1.8-3.0, corresponding to column density variations of ∼0.3-0.5 dex in the optically-thin approximation. Using FLAMES, FEROS, and UVES archive spectra, the minimum and maximum reduced equivalent widths for Milky Way gas are found to lie in the range ∼35-125 mÅ and ∼30-160 mÅ for Ca ii K and Na i D, respectively. The range is consistent with a previously published simple model of the interstellar medium consisting of spherical cloudlets of filling factor ∼0.3, although other geometries are not ruled out. Finally, the derived functional form for parallax (π) and Ca ii column density (N_CaII) is found to be π(mas) = 1 / (2.39 × 10^-13 × N_CaII (cm^-2) + 0.11). Our derived parallax is ∼25 per cent lower than predicted by Megier et al. (2009, A&A, 507, 833) at a distance of ∼100 pc and ∼15 percent lower at a distance of ∼200 pc, reflecting inhomogeneity in the Ca ii distribution in the different sightlines studied.

Multi-scale colorectal tumour segmentation using a novel coarse to fine strategy

This paper addresses the problem of colorectal tumour segmentation in complex real world imagery. For efficient segmentation, a multi-scale strategy is developed for extracting the potentially cancerous region of interest (ROI) based on colour histograms while searching for the best texture resolution. To achieve better segmentation accuracy, we apply a novel bag-of-visual-words method based on rotation invariant raw statistical features and random projection based l2-norm sparse representation to classify tumour areas in histopathology images. Experimental results on 20 real world digital slides demonstrate that the proposed algorithm results in better recognition accuracy than several state of the art segmentation techniques.

A novel methodology for analysis of large scale interconnected power and gas systems

The European Union continues to exert a large influence on the direction of member states energy policy. The 2020 targets for renewable energy integration have had significant impact on the operation of current power systems, forcing a rapid change from fossil fuel dominated systems to those with high levels of renewable power. Additionally, the overarching aim of an internal energy market throughout Europe has and will continue to place importance on multi-jurisdictional co-operation regarding energy supply. Combining these renewable energy and multi-jurisdictional supply goals results in a complicated multi-vector energy system, where the understanding of interactions between fossil fuels, renewable energy, interconnection and economic power system operation is increasingly important. This paper provides a novel and systematic methodology to fully understand the changing dynamics of interconnected energy systems from a gas and power perspective. A fully realistic unit commitment and economic dispatch model of the 2030 power systems in Great Britain and Ireland, combined with a representative gas transmission energy flow model is developed. The importance of multi-jurisdictional integrated energy system operation in one of the most strategically important renewable energy regions is demonstrated.

The reliability and factorial validity of the Adolescent Alcohol Involvement Scale in a large sample in the United Kingdom

The assessment of adolescent drinking behavior is a complex task, complicated by variability in drinking patterns, the transitory and developmental nature of the behavior and the reliance (for large scale studies) on self-report questionnaires. The Adolescent Alcohol Involvement Scale (Mayer & Filstead, 1979) is a 14-item screening tool designed to help to identify alcohol misusers or more problematic drinkers. The present study utilized a large sample (n = 4066) adolescents from Northern Ireland. Results of Confirmatory Factor Analyses and reliability estimates revealed that the 14-items share sufficient common variance that scores can be considered to be reliable and that the 14 items can be scored to provide a composite alcohol use score.

Studies on betanin natural dye incorporated ZnO composites at nano and micro scale for photonic device applications

Green energy and Green technology are the most of the quoted terms in the context of modern science and technology. Technology which is close to nature is the necessity of the modern world which is haunted by global warming and climatic alterations. Proper utilization of solar energy is one of the goals of Green Energy Movement. The present thesis deals with the work carried out in the eld of nanotechnology and its possible use in various applications (employing natural dyes) like solar cells. Unlike arti cial dyes, the natural dyes are available, easy to prepare, low in cost, non-toxic, environmentally friendly and fully biodegradable. Looking to the 21st century, the nano/micro sciences will be a chief contributor to scienti c and technological developments. As nanotechnology progresses and complex nanosystems are fabricated, a growing impetus is being given to the development of multi-functional and size-dependent materials. The control of the morphology, from the nano to the micrometer scales, associated with the incorporation of several functionalities can yield entirely new smart hybrid materials. They are special class of materials which provide a new method for the improvement of the environmental stability of the material with interesting optical properties and opening a land of opportunities for applications in the eld of photonics. Zinc oxide (ZnO) is one such multipurpose material that has been explored for applications in sensing, environmental monitoring, and bio-medical systems and communications technology. Understanding the growth mechanism and tailoring their morphology is essential for the use of ZnO crystals as nano/micro electromechanical systems and also as building blocks of other nanosystems.

Multi-scale score level fusion of local descriptors for gender classification in the wild

The 2015 FRVT gender classification (GC) report evidences the problems that current approaches tackle in situations with large variations in pose, illumination, background and facial expression. The report suggests that both commercial and research solutions are hardly able to reach an accuracy over 90% for The Images of Groups dataset, a proven scenario exhibiting unrestricted or in the wild conditions. In this paper, we focus on this challenging dataset, stepping forward in GC performance by observing: 1) recent literature results combining multiple local descriptors, and 2) the psychophysics evidences of the greater importance of the ocular and mouth areas to solve this task...

Renar och vindkraft II : Vindkraft i drift och effekter på renar och renskötsel

Utbyggnaden av vindkraft inom renskötselområdet har ökat markant det senaste decenniet, trots att kunskapen om påverkan av vindkraftsetableringar ännu inte är fullt utredd och dokumenterad. I den här rapporten beskriver vi framförallt hur vindkraftparker i driftsfas påverkar renarna och renskötseln i tre olika områden. I Malå sameby har vi studerat kalvningsområdet kring Storliden och Jokkmokkslidens vindkraftparker. I Vilhelmina Norra sameby har vi studerat vinterbetesområdet kring Stor-Rotlidens vindkraftpark, samt Lögdeålandets betesområde med Gabrielsbergets vindkraftpark som används av Byrkije reinbetesdistrikt från Norge. För att få en helhetsbild av hur renarna använder sitt betesområde är det viktigt att studera renarnas betes- och förflyttningsmönster långsiktigt och över hela deras betesområde och inte bara inom det lokala området nära parken. Det är också viktigt att ta hänsyn till att renarnas betesutnyttjande skiftar från år till år och mellan olika årstider beroende på väderlek och andra yttre förutsättningar. Vi vill också understryka vikten av att kombinera den traditionella kunskapen från renskötarna med vedertagna vetenskapliga analysmetoder för att besvara de frågor som är viktiga för att kunna bedriva en hållbar renskötsel. Vi har undersökt renarnas användning av områdena genom att utföra spillningsinventeringar under åren 2009-2015 (endast i Malå sameby), och genom att följa renar utrustade med GPS-halsband under åren 2005-2015. Datat är insamlat före och under byggfas och under driftsfas (för Gabrielsberget finns GPS-data endast för driftsfasen). Vi har analyserat data genom att utveckla statistiska modeller för val av betesområde för varje område där vi har beräknat hur renarna förhåller sig till vindkraftparksområdet före, under och efter byggnation, och på Gabrielsberget när parken varit avstängd under 40 dagar och under drift vid olika renskötselsituationer. Genom intervjuer, möten och samtal, samt information från Gabrielsbergets vindkraftparks kontrollprogram, har vi tagit del av renskötarnas erfarenheter av hur renarnas beteende, och därmed även renskötseln, påverkats av vindkraftsutbyggnaden i respektive område. Våra resultat visar att renarna både på kalvnings- och på vinterbetesområden påverkas negativt av vindkraftsetableringarna (Tabell a). Renarna undviker att beta i områden där de kan se och/eller höra vindkraftsverken och föredrar att vistas i områden där vindkraftverken är skymda. I kalvningsområdet i Malå ökade användningen av skymda områden med 60 % under driftsfas. I vinterbetesområdet på Gabrielsberget, när renarna utfodrades i parken och kantbevakades intensivt för att stanna i parkområdet under driftsfas, ökade användningen av skymda områden med 13 % jämfört med när de inte var utfodrade och fick ströva mer fritt. Resultaten visar också att renarna minskar sin användning av området nära vindkraftparkerna. I kalvningslandet i Malå minskar renarna sin användning av områden inom 5 km från parkerna med 16-20 %. Vintertid vid Gabrielsbergets vindkraftpark undvek renarna parken med 3 km. Våra resultat visar även att renarnas betesro minskar inom en radie på 4 km från vindkraftparkerna under kalvningsperioden och tiden därefter i jämförelse med perioden före byggfas. Exakta avstånd som renarna påverkas beror på förutsättningarna i respektive område, exempelvis hur topografin ser ut eller om området är begränsat av stängsel eller annan infrastruktur. Förändringarna i habitatutnyttjande i våra studieområden blev tydligare när parkerna var centralt belägna i renarnas betesområde, som i kalvningsområdet i Malå eller i vinterbeteslandet på Gabrielsberget, medan det inte var lika tydliga effekter kring Stor-Rotlidens park, som ligger i utkanten av ett huvudbetesområde. Oftast är snöförhållandena bättre ur betessynpunkt högre upp i terrängen än nere i dalgångarna, på grund av stabilare temperatur, vind som blåser bort snötäcket och mer variation i topografin. Därför kan etablering av vindkraftparker i höglänta områden försämra möjligheten att använda sådana viktiga reservbetesområden under vintrar med i övrigt dåliga snöförhållanden, vilka blir allt vanligare i och med klimatförändringarna. Våra resultat tyder inte direkt på att renarna påverkats negativt under dåliga betesvintrar men fler år av studier behövs för att ytterligare klargöra hur vindkraft påverkar renarna under dessa vintrar. Våra studier har visat att etablering av vindkraft har konsekvenser för renskötseln under både barmarkssäsongen och under vintern, men effekterna förmodas få störst inverkan inom vinterbetesområdet där det är svårt att hitta alternativa betesområden för renarna. Under sommaren är betestillgången oftast mindre begränsad och renarna kan lättare hitta alternativa områden. En direkt konsekvens av Gabrielsbergets vindkraftpark som är placerad mitt i ett vinterbetesområde har blivit att renarna behöver tillskottsutfodras och bevakas intensivare för att de inte ska gå ut ur området. När den naturliga vandringen mellan olika betesområden störs för att renarna undviker att vistas i ett område kan det leda till att den totala tillgången till naturligt bete minskar och att man permanent måste tillskottsutfodra, alternativt minska antalet renar. Annan infrastruktur som vägar och kraftledningar påverkar också renarna. Vid Storliden och Jokkmokksliden och vid Stor-Rotliden där data samlats in innan vindkraftparken uppfördes visar våra resultat att renarna undviker de omkringliggande landsvägarna redan innan parkerna etablerades. Vid Stor-Rotliden ökar dock renarna användningen av områden nära vägarna efter att parken är byggd. På Gabrielsberget, där vi endast har data under drifttiden, är renarna närmare vägarna (även stora vägar som E4) när renskötarna minskar på kantbevakningen för att inte hålla renarna nära parken. Detta ökar naturligtvis risken för trafikolyckor och innebär att renskötarna måste bevaka dessa områden intensivare. Sist i rapporten presenterar vi förslag till åtgärder som kan användas för att underlätta arbetet för renskötseln om det är så att en vindkraftpark redan är byggd. Några exempel på åtgärder som är direkt kopplat till parken är att stänga av vägarna in i vindkraftparken för att förhindra nöjeskörning med skoter och bil under den tiden renarna vistas i området samt tät dialog mellan vindkraftsbolag och sameby angående vinterväghållningen av vägarna till och inom vindkraftparken. Andra mer regionala åtgärder för att förbättra förutsättningarna för renskötselarbetet på andra platser för samebyn, kan vara att sätta stängsel längst större vägar och järnvägar (t.ex. E4:an eller stambanan) i kombination med strategiskt utplacerade ekodukter. Detta för att underlätta och återställa möjligheterna till renarnas fria strövning och renskötarnas flytt av renar mellan olika betesområden.   

Propiedades psicométricas: ADHD Rating Scale IV en formato autoreporte

El instrumento ADHD Rating Scale IV (ADHD RS IV) es un cuestionario de 18 ítems que permite valorar el déficit de atención, la hiperactividad e impulsividad que conforman el trastorno por déficit de atención con hiperactividad (TDAH). El aporte del presente estudio a la línea de investigación del TDAH se basa en el análisis de las propiedades psicométricas del instrumento en una adaptación en formato de auto-reporte, además, se trata de un estudio no realizado previamente en el contexto ecuatoriano.

Large-scale Roll Out of Online Prospective Measurement of Mood Symptoms in Affective Disorders

Background and Aims: True Colours is an online prospective mood-monitoring system developed at the University of Oxford to assist local patients and clinicians with monitoring course of illness in bipolar disorder. We report our initial experiences of using True Colours for research purposes in the Bipolar Disorder Research Network (BDRN; www.bdrn.org), a large research network of individuals with mood disorders spread throughout the UK. Methods: After initial piloting to ensure the practicality/acceptability of using True Colours within BDRN, we invited all BDRN participants (n = 7000) to participate in weekly True Colours ratings via three postal invitations sent over an 8-month period. Results: Following the three postal invitations, 915 individuals have so far expressed an interest in joining True Colours, and, of these, 662 (72.3%) have registered. 32 of those who registered for True Colours (5%) have so far asked to leave the system. Positive feedback from participants has focused around the ease of use and convenience of True Colours and potential clinical utility of the graphical representation of weekly mood scores. Conclusions: We have demonstrated that large-scale prospective mood monitoring for research purposes using a contemporary online approach is feasible. Challenges have included: (i) variation in participants’ technological ability; (ii) management of requests for clinical advice based on mood scores within a research setting; and, (iii) resources required to provide access and on-going support for participants using True Colours. We continue to expand recruitment to True Colours within BDRN, and plan to trial email invitations in the next phase of recruitment.

Soil organic carbon stocks in estuarine and marine mangrove ecosystems are driven by nutrient colimitation of P and N

Mangroves play an important role in carbon sequestration, but soil organic carbon (SOC) stocks differ between marine and estuarine mangroves, suggesting differing processes and drivers of SOC accumulation. Here, we compared undegraded and degraded marine and estuarine mangroves in a regional approach across the Indonesian archipelago for their SOC stocks and evaluated possible drivers imposed by nutrient limitations along the land-to-sea gradients. SOC stocks in natural marine mangroves (271–572 Mg ha-1 m-1 were much higher than under estuarine mangroves (100–315 Mg ha-1 m-1 with a further decrease caused by degradation to 80–132 Mg ha-1 m-1. Soils differed in C/N ratio (marine: 29–64; estuarine: 9–28), δ15N (marine: 0.6 to 0.7‰; estuarine: 2.5 to 7.2‰), and plant-available P (marine: 2.3–6.3 mg kg-1; estuarine: 0.16–1.8 mg kg-1). We found N and P supply of sea-oriented mangroves primarily met by dominating symbiotic N2 fixation from air and P import from sea, while mangroves on the landward gradient increasingly covered their demand in N and P from allochthonous sources and SOM recycling. Pioneer plants favored by degradation further increased nutrient recycling from soil resulting in smaller SOC stocks in the topsoil. These processes explained the differences in SOC stocks along the land-to-sea gradient in each mangrove type as well as the SOC stock differences observed between estuarine and marine mangrove ecosystems. This first large-scale evaluation of drivers of SOC stocks under mangroves thus suggests a continuum in mangrove functioning across scales and ecotypes and additionally provides viable proxies for carbon stock estimations in PES or REDD schemes.

Detection of mesoscale thermal fronts from 4km data using smoothing techniques: Gradient-based fronts classification and basin scale application

In order to optimize frontal detection in sea surface temperature fields at 4 km resolution, a combined statistical and expert-based approach is applied to test different spatial smoothing of the data prior to the detection process. Fronts are usually detected at 1 km resolution using the histogram-based, single image edge detection (SIED) algorithm developed by Cayula and Cornillon in 1992, with a standard preliminary smoothing using a median filter and a 3 × 3 pixel kernel. Here, detections are performed in three study regions (off Morocco, the Mozambique Channel, and north-western Australia) and across the Indian Ocean basin using the combination of multiple windows (CMW) method developed by Nieto, Demarcq and McClatchie in 2012 which improves on the original Cayula and Cornillon algorithm. Detections at 4 km and 1 km of resolution are compared. Fronts are divided in two intensity classes (“weak” and “strong”) according to their thermal gradient. A preliminary smoothing is applied prior to the detection using different convolutions: three type of filters (median, average and Gaussian) combined with four kernel sizes (3 × 3, 5 × 5, 7 × 7, and 9 × 9 pixels) and three detection window sizes (16 × 16, 24 × 24 and 32 × 32 pixels) to test the effect of these smoothing combinations on reducing the background noise of the data and therefore on improving the frontal detection. The performance of the combinations on 4 km data are evaluated using two criteria: detection efficiency and front length. We find that the optimal combination of preliminary smoothing parameters in enhancing detection efficiency and preserving front length includes a median filter, a 16 × 16 pixel window size, and a 5 × 5 pixel kernel for strong fronts and a 7 × 7 pixel kernel for weak fronts. Results show an improvement in detection performance (from largest to smallest window size) of 71% for strong fronts and 120% for weak fronts. Despite the small window used (16 × 16 pixels), the length of the fronts has been preserved relative to that found with 1 km data. This optimal preliminary smoothing and the CMW detection algorithm on 4 km sea surface temperature data are then used to describe the spatial distribution of the monthly frequencies of occurrence for both strong and weak fronts across the Indian Ocean basin. In general strong fronts are observed in coastal areas whereas weak fronts, with some seasonal exceptions, are mainly located in the open ocean. This study shows that adequate noise reduction done by a preliminary smoothing of the data considerably improves the frontal detection efficiency as well as the global quality of the results. Consequently, the use of 4 km data enables frontal detections similar to 1 km data (using a standard median 3 × 3 convolution) in terms of detectability, length and location. This method, using 4 km data is easily applicable to large regions or at the global scale with far less constraints of data manipulation and processing time relative to 1 km data.