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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>IWSG</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>A Science Gateway for Biodiversity and Climate Change Research</article-title>
      </title-group>
      <contrib-group>
        <aff id="aff0">
          <label>0</label>
          <institution>Centro de Refereˆncia em Informac ̧a ̃o Ambiental</institution>
          ,
          <addr-line>Campinas, SP</addr-line>
          ,
          <country country="BR">Brasil</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Donatello Elia</institution>
          ,
          <addr-line>Alessandra Nuzzo , Paola Nassisi , Sandro Fiore , Ignacio Blanquer</addr-line>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2016</year>
      </pub-date>
      <volume>8</volume>
      <fpage>8</fpage>
      <lpage>10</lpage>
      <abstract>
        <p>-Climate and biodiversity systems are closely interlaced across a wide range of scales. To better understand the mutual interaction between climate change and biodiversity there is a strong need for multidisciplinary skills, tools and a large variety of heterogeneous, distributed data sources. In this regard, the EUBrazilCloudConnect project provides a usercentric research environment built on top of a federated cloud infrastructure across Europe and Brazil to serve scientific needs. One of the test cases implemented in this project focuses on climate change and biodiversity research. The BioClimate is the Science Gateway of the use case. It aims at providing end-users with a highly integrated environment, addressing mainly data analytics requirements. This paper presents a complete overview about BioClimate and the scientific environment delivered to the user community at the end of the project.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>I. INTRODUCTION</title>
      <p>Climate and biodiversity systems are closely interlaced
across a wide range of scales. In order to predict the effects of
climate change on the biodiversity system, which is essential
towards sustainable landscape and eco-services management,
there is a need to further investigate the interaction between
the climate system and biodiversity.</p>
      <p>Direct measurements of climate and biodiversity are often
difficult and time-consuming to obtain, instead it is common
practice to use climate and biodiversity indicators. These
interactions can be studied at various scales, ranging from
microscopic scales, and at (genomic, taxonomic, ecosystem)
scales of individual plant and animal species. A multi-scale
and integrated approach is required to investigate the
climatebiodiversity system as a whole. Presently, in this scenario,
researchers and professionals are burdened by scattered data
sources, wealth of analysis tools to master and implement, and
computational limitations to upscale their analysis.</p>
      <p>
        EUBrazilCloudConnect [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] is a project from the third
coordinated EU-Brazil call. It is a preliminary step towards
providing a user-centric environment for the scientific research
communities to test the execution of challenging applications
exploiting a federated cloud infrastructure. The project
addresses the scientific challenges of three multidisciplinary and
highly complementary scenarios, among which the one on
biodiversity, natural resources and climate change represents
the most challenging one from the scientific data management
standpoint. The proposed scientific scenarios require access to
the project e-infrastructure to run complex workflow pipelines
as well as access to heterogeneous and large datasets for data
analysis and visualisation.
      </p>
      <p>The Biodiversity and Climate Change use case (BioClimate)
involves multiple heterogeneous data sources (e.g. SEBAL,
LiDAR, CRU, CMIP5, speciesLink, GBIF, etc.) and several
processing pipelines, integrated through the BioClimate
Scientific Gateway. The gateway sits on top of the databases and
enables near-real-time analysis of large volume datasets (from
multi-GBs to multi-TBs scale depending on the specific data
source) through the Parallel Data Analysis Service (PDAS).
PDAS clusters are deployed on the site where the databases
are stored providing the end-user with a high-level, parallel,
and server-side interface for scientific data analysis.</p>
      <p>The design of the software infrastructure and the
BioClimate Scientific Gateway for end-users facilitates joint research
using data that is otherwise difficult to access or for which
availability is fragmented and/or too large to process using
traditional computational means. With regard to existing
approaches and tools that are mainly client-side/desktop based,
the use case delivers a well-integrated environment for climate
change and biodiversity research with cloud-based
infrastructure and server-side capabilities.</p>
      <p>This work presents the BioClimate Scientific Gateway, the
scientific challenges addressed and the implementation details.
The remainder of this work is organised as it follows. Section
II provides an overview of the BioClimate use case and its
main goals. Section III provides a general description of the
BioClimate Scientific Gateway architecture, whereas Section
IV and Section V give, respectively, a detailed description of
the graphic interface and the back-end. Finally, Section VI
draws the main conclusions and describes the future activities.
II. A BIODIVERSITY &amp; CLIMATE CHANGE USE CASE
The EUBrazilCloudConnect (EUBrazilCC) use case on
climate change and biodiversity is a data-driven use case,
aiming at better understanding the interactions between the
biodiversity system and the climate system. This use case
focuses on bringing together a wide variety of climate and
biodiversity data and analysis tools into a user-friendly and
web-based Science Gateway to provide an integrated approach
of investigating climate and biodiversity across different
temporal and spatial scales.</p>
      <p>To address all these scientific challenges, the use case
joins together heterogeneous data sources, on-premises cloud
infrastructures, multiple data services, and a Science Gateway
into a single, federated trans-Atlantic environment.</p>
      <p>
        The Science Gateway provides access to historical
temperature and precipitation records, different climate model
scenarios with predictions of future temperature and precipitation,
Landsat [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] satellite imagery for climate and biodiversity
indicators, LiDAR 3D forest metrics and biodiversity indicators at
a very high resolution, and plant occurrences data for
ecological niche models for the prediction of future plant distribution
based on different climate scenarios. The proposed pipelines/
workflows combine the analysis of data acquired from these
different technologies to study the impact of climate change in
regions with high interest for biodiversity conservation, such
as the Brazilian Amazon and the semi-arid Caatinga regions
in Brazil. The analysis of remote sensing images provides 3D
information concerning the structure of the vegetation, which
improves biodiversity indicators such as the energy balance
and evapotranspiration.
      </p>
      <p>The EUBrazilCC infrastructure provides the computing
power needed to support data processing and analysis, the
management of metadata to enable search and discovery
as well as provenance management to address re-usability
and reproducibility, both strongly relevant for scientific data
environments. The BioClimate Scientific Gateway integrates in
a web-based environment the data sources and the processing
and analysis capabilities exploiting the project infrastructure.
More specifically, the gateway has been designed to fulfil some
key requirements:</p>
      <p>Integration of heterogenous data sources. The gateway
provides a unified interface to access and process satellite
images (from Landsat), environmental data, future
climate scenarios, biodiversity data like species distributions
and LiDAR datasets related to some target areas.
Furthermore, the gateway provides also metadata information
describing these data sources.</p>
      <sec id="sec-1-1">
        <title>Implementation of processing tools. To support data</title>
        <p>
          analysis, several tools are integrated in the gateway to
allow: computation of 3D vegetation products based on
LiDAR data [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ] (e.g. Digital Surface Model (DSM),
Digital Terrain Model (DTM), Canopy Height Model (CHM),
Relative Height at 50% (RH50)), execution of Ecological
Niche Modeling over species data and processing of
datasets from climate models and the SEBAL algorithm.
Usability. The interface is designed to: (i) facilitate the
end-user to select the target data source, an area of
interest and the temporal scale; (ii) submit an experiment
computation; (iii) visualise the processed results in terms
of maps, graphs, tables and comparative charts; and (iv)
download the aggregated results and products regarding
satellite images and 3D vegetation products (CSV, Raster,
GeoTIFF and PNG formats).
        </p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>III. GATEWAY ARCHITECTURE</title>
      <p>The software architecture of the use case is shown in Figure
1. The BioClimate Scientific Gateway represents the high-level
user interface provided by the use case. It allows data access,
analysis and visualisation over multiple, heterogeneous data
sources, by exposing an integrated view of the data level. It
supports several features, such as time-series and statistical
analysis, data inspection, intercomparison and subsetting.</p>
      <p>
        The elastic-job engine takes care of the execution of the
requests submitted through the gateway interface by translating
the requests in PDAS tasks and then properly scheduling
the jobs on the available resources. To guarantee scalability,
it elastically adapts to the analytics workload exploiting the
underlying cloud resources. The engine interacts with the
Infrastructure Manager (IM) [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] to deploy and un-deploy
PDAS cluster instances on-demand. A detailed description of
the implementation and the main features of both the Science
Gateway interface and the engine is provided in the next
sections.
      </p>
      <p>A system catalog is used by both the front-end and the
backend to store useful information regarding user management,
experiment execution requests and results, PDAS cluster usage
history and it also serves as a centralised data repository.</p>
      <p>
        The PDAS, a core component of the Ophidia project [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ],
provides support in terms of data analytics applied to large
scientific datasets. It includes functionalities to deal with different
scientific data formats, such as NetCDF (Network Common
Data Form) [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] and satellite data, and allow mathematical and
statistical operations on this data. Python scripts, integrated in
the PDAS, provide additional functionalities to process LiDAR
products and interact with external tools (e.g GDAL [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]) and
services (e.g OpenModeller [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]).
      </p>
      <p>The gateway also provides access to the BioClimate
Clearing House, a database where the user can persistently store
the results of the experiment run during a session and retrieve
them through the search functionalities.</p>
      <p>The lowest layer of the diagram comprises the several
private clouds, running OpenNebula or OpenStack at the
Infrastructure as a Service (IaaS) level, and the data sources,
made available by the project partners or already available
from national and international agencies, which are part of
the infrastructure with a more static setup.</p>
      <p>The data sources integrated through the gateway are
reported in the following:</p>
      <p>
        SEBAL datasets. These are an output of satellite images
series (Landsat) processed by the SEBAL [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ], [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]
algorithm to produce estimates of energy balance and
evapotranspiration of water to the atmosphere. Remote
sensing data are provided by the United States Geological
Survey (USGS) and the National Aeronautics and Space
Administration (NASA). In particular, the infrastructure
allows processing of Landsat data coming from the
Brazilian Semiarid region.
      </p>
      <p>
        LiDAR data. For the areas near Manaus in Brazil, where
hyper-spectral imagery is apparently absent, EUBrazil
Cloud Connect will leverage of the available LiDAR data
provided by EMBRAPA [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] (Brazilian Agricultural and
Livestock Research Corporation). Vegetation and terrain
metrics represent the key indicators that can be inferred
from these datasets.
      </p>
      <p>
        Biodiversity data sources. The speciesLink datasets [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ],
provided by CRIA, the Reference Center on
Environmental Information, are an output of networking activities
to provide free and open access to 7.3 million primary
research-grade data, derived from the federation of 350
Brazilian biodiversity datasets, gathered from 150
institutions in Brazil and abroad. They represent valuable
biodiversity data sources.
      </p>
      <sec id="sec-2-1">
        <title>Climate data from the CMIP5 Federated Data Archive</title>
        <p>
          (ESGF) [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ]. The Coupled Model Intercomparison
Project (CMIP) provides a community-based
infrastructure in support of climate model diagnosis, validation,
intercomparison, documentation and data access. CMCC
provides about 100TB of data related to three different
models, NetCDF format, CF conventions. Starting from
these datasets, multiple climate indicators can be
computed.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>Climate data from observed data. These high-resolution</title>
        <p>
          gridded datasets (CRU TS v.3.23 [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ]) provide monthly
values for several variables, such as temperature and
precipitation, for an historical time period and are made
available under the Open Database License by Climatic
Research Unit, University of East Anglia.
        </p>
        <p>
          Finally, security cuts across the whole architecture and
is taken into account at several levels. With regard to the
front-end, the security is implemented in terms of user
authentication. In order to avoid potential attacks that aim at
stealing passwords, the system employs a technique based on
salted password hashing, based on a Java implementation of a
Cryptographically Secure Pseudo-Random Number Generator,
called Password-Based Key Derivation Function 2 (PBKDF2)
[
          <xref ref-type="bibr" rid="ref16">16</xref>
          ]. Additionally, HTTPS is used to provide encryption for
the communications between client and server.
        </p>
        <p>
          At the elastic-job engine level, the PDAS terminal is used
to send requests to a PDAS server interface. It can exploit
the X509v3 digital certificates-based authentication and the
VOMS-based authorisation. Different levels of privileges are
defined to distinguish user roles locally at each PDAS server or
globally at the VOMS server. For this purpose, a GSI/VOMS
enabled interface, supporting both X.509 certificates and
VOMS-based authorisation and addressing the interoperability
with the EGI Fed Cloud environment [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ], has been defined.
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>IV. USER INTERFACE INSIGHTS</title>
      <p>In order to address portability of the system and the
separation of concerns between the presentation layer and the
business logic, the gateway has been implemented according
to the Model-View-Controller pattern.</p>
      <p>
        The presentation layer, running on the client side (i.e. a
browser), provides a rich user interface to submit the data
analysis tasks and visualise their results. It is implemented as
a JavaScript web application based on the ExtJS library [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ],
which offers a number of gadgets such as panels, charts and
grids, and Google Maps API [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] for the visualisation of
georeferenced data.
      </p>
      <p>
        The server side of the Science Gateway implements the
business logic to manage users, handle the requests and the
post-processing of the results and is based on Java and Apache
Struts2 framework [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ].
      </p>
      <p>To increase the performance and make the output
visualisation faster, it has been decided to perform the heavier tasks,
related to the post-processing of the outputs, on the server side
and to present the ready-to-use result to the JavaScript library
on the presentation layer.</p>
      <p>Usability has been addressed by defining and
implementing a set of pre-defined experiments regarding the different
data sources and type of analysis. Each experiment defines
a customisable template to perform data analytics tasks on
climate and biodiversity data and requires a specific pipeline
of operations, including subsetting, data reduction and
mathematical/statistical functions.</p>
      <p>The following subsections provide a description of the main
views and interfaces made available by the gateway.</p>
      <sec id="sec-3-1">
        <title>A. Interactive analysis</title>
        <p>The ”Interactive analysis” panel allows a real-time,
exploratory analysis of time series from the climate data available
in the use case. In particular, it provides access to CRU
historical data (temperature and precipitation variables) and
future simulated data from the CMIP5 experiment (maximum
and minimum temperatures from different climate models and
scenarios).</p>
        <p>As shown in Figure 2, the interface allows the selection
of a dataset and a variable from the list of datasets/variables
available and a point from the map. The bottom section of the
Science Gateway displays the result of the analysis in terms
of: (i) a chart with the time series and its trend line and (ii) a
table with a comprehensive set of aggregated statistics.</p>
      </sec>
      <sec id="sec-3-2">
        <title>B. Batch analysis</title>
        <p>The ”Compute” panel provides the features to define and
submit complex experiments regarding the available data
sources. For each experiment, a map for spatial selection and
a form to set the input parameters is provided. The following
experiments are defined:</p>
      </sec>
      <sec id="sec-3-3">
        <title>Interannual analysis of SEBAL output (see Figure 3)</title>
        <p>provides information about interannual trends and
statistical information of a specific SEBAL variable. The
Science Gateway integrates data processed by the SEBAL
algorithm and provides functionalities to analyse several
variables produced by this algorithm (e.g. Enhanced
Vegetation Index, Leaf Area Index, Normalized
Difference Vegetation index, etc.). The interface allows both
spatial and temporal selection.</p>
        <p>Climate and SEBAL variables intercomparison allows
the comparison of the behaviour of climate and SEBAL
variables. In particular it supports analysis over the
variables produced by the SEBAL algorithm and variables
(precipitation and temperature) from historical climate
data. From a scientific point of view, this experiment
provides useful information about the relationship between
climate and vegetation indices.</p>
      </sec>
      <sec id="sec-3-4">
        <title>Climate indices intercomparison allows comparison of</title>
        <p>
          indicators computed on CMIP5 datasets belonging to
different climate models and future emission scenarios
(RCP4.5 and RCP8.5 [
          <xref ref-type="bibr" rid="ref21">21</xref>
          ]). Four well-known indicators
        </p>
        <p>
          Fig. 4. SEBAL Interannual analysis details interface
based on maximum and minimum temperature are
available for comparison (i.e. TXx, TNx, TXn, TNn [
          <xref ref-type="bibr" rid="ref22">22</xref>
          ]).
Ecological Niche Modelling (ENM) experiment integrates
the functionalities available through the OpenModeller
Web Service API to create and project models defined
over occurrences of biodiversity data. This experiment
allows the comparison of the projections of models into
three different environmental scenarios (present, future
optimistic and future pessimistic). The models are created
with the maximum entropy algorithm [
          <xref ref-type="bibr" rid="ref23">23</xref>
          ] and are based
on the species occurrences selected by the user.
        </p>
      </sec>
      <sec id="sec-3-5">
        <title>LiDAR products intercomparison allows comparison and</title>
        <p>evaluation of the statistical relationship between LiDAR
products available through the gateway (e.g. DSM, DTM,
CHM). In this case, a LiDAR tile can be selected from
the map.</p>
      </sec>
      <sec id="sec-3-6">
        <title>Relative Height analysis of LiDAR data provides infor</title>
        <p>mation about relative height at different percentiles (25%,
50%, 66%, 75% and 90%) of the points in a LiDAR tile.</p>
      </sec>
      <sec id="sec-3-7">
        <title>C. Experiment visualisation &amp; download</title>
        <p>Once the computation of the experiment is completed,
details about the experiment are available through the
”Experiment Details” section. Figure 4 displays the output produced
by a SEBAL interannual experiment, whereas Figure 5 and
Figure 6 display the output produced by a LiDAR
intercomparison experiment and Climate-SEBAL intercomparison
experiment respectively.</p>
        <p>In particular, to better suit the experiment peculiarities, a
specific detail view is provided for each experiment defined
above. Hence, various gadgets organised in different fashions
are used to display the results, among these are: line charts
to display statistical values and trend lines; scatter plots to
evaluate variable and indicators correlation; tables to show
the results and statistical values; maps with the environmental
scenario; images of the LiDAR products; and histograms of
the point distribution.</p>
        <p>Most of the information provided through the gadgets is
also available for download in CSV, raster, GeoTIFF or PNG
format, depending on the type of experiment run. Furthermore,
metadata regarding the experiment is available in the same
view.</p>
      </sec>
      <sec id="sec-3-8">
        <title>D. BioClimate Clearing House</title>
        <p>The BioClimate Clearing House system allows users to
store a relevant experiment, run during a session, for future
analysis. A smart search feature is available to filter out the
experiments saved into the Clearing House, based on: (i)
spatial domain used for the experiment, (ii) experiment type
and (iii) submission date.</p>
      </sec>
      <sec id="sec-3-9">
        <title>E. Infrastructure Monitoring</title>
        <p>The BioClimate Scientific Gateway includes two
administrative interfaces that (i) allow managing users and their
privileges and (ii) provide some information about the
resources exploited dynamically by the gateway (i.e. PDAS
cluster instances) as well as some statistics regarding the
number of experiments executed in terms of their type and
status. Through this dashboard (see Figure 7) it is possible to
get some insights about the use of the system by the end-users.
The charts mainly provide real-time monitoring information
regarding the number of experiments running/pending and the
status of the resources. In particular, a histogram shows the set
of experiments and their distribution across the active PDAS
instances for the last couple of minutes, whereas a pie chart
shows the set of clusters currently running the experiments.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>V. ELASTIC-JOB ENGINE</title>
      <p>The elastic-job engine is designed to guarantee fast
processing of the user requests by exploiting dynamically and
elastically the federated cloud infrastructure. To meet scalability and
performance requirements, the engine is implemented as
multithreaded daemon, based on GNU C libraries, that exploits the
PDAS capabilities to perform pipelines of analytics tasks.</p>
      <p>Data-driven processing pipelines, based on PDAS operators,
have been defined integrating different tools, services and data
formats.</p>
      <p>
        Management of the workload is performed exploiting a
smart scheduling algorithm, which provides dynamic job
scheduling over a set of queues. A job queue is associated to
each PDAS cluster running on the infrastructure. To
horizontally scale on the workload, a new PDAS instance is deployed
automatically on the private cloud resources when the number
of pending jobs on all the queues exceed a configurable
threshold. A more detailed description of the automated cloud
deployment (through the elastic-job engine) of the PDAS, as
well as of the queue policy adopted and its rationale, are out
of the scope of this paper and can be found in [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ].
      </p>
      <sec id="sec-4-1">
        <title>A. PDAS</title>
        <p>As mentioned before, the PDAS provides the capabilities to
perform data analytics on large scientific datasets and includes
a set of libraries able to deal with different data formats. In the
EUBrazilCC project, the PDAS addresses scientific challenges
related to the BioClimate use case and it is used for, both batch
and interactive data analysis on NetCDF, LiDAR and remote
sensing data.</p>
        <p>All the outputs of the PDAS are stored in JSON format. This
eases the integration of the results into web-contexts like the
BioClimate Scientific Gateway and the parsing of the outputs
from JavaScript and Python-based applications.</p>
        <p>
          To address the data analytics requirements and support the
processing pipelines of the use case, several new features
and mathematical functionalities have been developed during
the project lifetime. In particular, regarding the interactive
analysis, an operator that allows data inspection and
on-thefly exploration of time series has been implemented, whereas
to run the batch experiments, processing pipelines made up
of several new operators and functions have been defined. To
integrate external tools, an operator to run scripts has also
been developed. Besides the previous extensions, the import
process has also been optimised to reduce the time required
to import large-scale datasets such as SEBAL output data.
Finally, to automate the deployment of PDAS instances in
the EUBrazilCC federated infrastructure, some cloud-based
scenarios, based on RADL files [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ], have been implemented
as reported in detail in [
          <xref ref-type="bibr" rid="ref24">24</xref>
          ].
        </p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>VI. CONCLUSION</title>
      <p>During the final validation phase of the EUBrazilCC project,
the BioClimate use case was highly appreciated by the
endusers, due to its ability to provide and deliver in the same
environment tools, pipelines, analysis/visualisation features,
and several data sources in an integrated manner.</p>
      <p>User experience was good and the change of paradigm
(process the data on the server-side) was evaluated as the
key added value. Despite it requires a learning process, the
BioClimate Scientific Gateway provides multiple views and
analyses of the retrospective data gathered. High level user
experience and usability have been two key requirements
considered in the implementation phase.</p>
      <p>A lot of interest was also raised by governmental &amp;
environmental agencies (both research &amp; education) especially in
Brazil. A set of follow-up actions will be put in place from the
different partners even beyond the project lifetime (that was
part of the project sustainability plan).</p>
      <p>Finally, the impact on the user community was very high.
The gateway was evaluated as seamlessly, flexibly and
efficiently able to integrate a comprehensive and useful set
of scientific data management tools to increase the mutual
understanding between climate change and biodiversity.</p>
    </sec>
    <sec id="sec-6">
      <title>ACKNOWLEDGMENT</title>
      <p>This work was supported by the EU FP7 EUBrazilCC
Project (Grant Agreement 614048), and CNPq/Brazil (Grant</p>
    </sec>
  </body>
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