Next Issue
Previous Issue

Table of Contents

Challenges, Volume 5, Issue 2 (December 2014), Pages 193-503

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-19
Export citation of selected articles as:

Research

Jump to: Review, Other

Open AccessArticle Planetary Atmosphere and Surfaces Chamber (PASC): A Platform to Address Various Challenges in Astrobiology
Challenges 2014, 5(2), 213-223; doi:10.3390/challe5020213
Received: 30 June 2014 / Revised: 29 July 2014 / Accepted: 30 July 2014 / Published: 8 August 2014
Cited by 1 | PDF Full-text (510 KB) | HTML Full-text | XML Full-text
Abstract
The study of planetary environments of astrobiological interest has become a major challenge. Because of the obvious technical and economical limitations on in situ planetary exploration, laboratory simulations are one of the most feasible research options to make advances both in planetary [...] Read more.
The study of planetary environments of astrobiological interest has become a major challenge. Because of the obvious technical and economical limitations on in situ planetary exploration, laboratory simulations are one of the most feasible research options to make advances both in planetary science and in developing a consistent description of the origin of life. With this objective in mind, we applied vacuum technology to the design of versatile vacuum chambers devoted to the simulation of planetary atmospheres’ conditions. These vacuum chambers are able to simulate atmospheres and surface temperatures representative of the majority of planetary objects, and they are especially appropriate for studying the physical, chemical and biological changes induced in a particular sample by in situ irradiation or physical parameters in a controlled environment. Vacuum chambers are a promising potential tool in several scientific and technological fields, such as engineering, chemistry, geology and biology. They also offer the possibility of discriminating between the effects of individual physical parameters and selected combinations thereof. The implementation of our vacuum chambers in combination with analytical techniques was specifically developed to make feasible the in situ physico-chemical characterization of samples. Many wide-ranging applications in astrobiology are detailed herein to provide an understanding of the potential and flexibility of these experimental systems. Instruments and engineering technology for space applications could take advantage of our environment-simulation chambers for sensor calibration. Our systems also provide the opportunity to gain a greater understanding of the chemical reactivity of molecules on surfaces under different environments, thereby leading to a greater understanding of interface processes in prebiotic chemical reactions and facilitating studies of UV photostability and photochemistry on surfaces. Furthermore, the stability and presence of certain minerals on planetary surfaces and the potential habitability of microorganisms under various planetary environmental conditions can be studied using our apparatus. Therefore, these simulation chambers can address multiple different challenging and multidisciplinary astrobiological studies. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Figures

Open AccessArticle What Does It Take to Establish that a World Is Uninhabited Prior to Exploitation? A Question of Ethics as well as Science
Challenges 2014, 5(2), 224-238; doi:10.3390/challe5020224
Received: 25 June 2014 / Revised: 30 July 2014 / Accepted: 4 August 2014 / Published: 12 August 2014
Cited by 2 | PDF Full-text (282 KB) | HTML Full-text | XML Full-text
Abstract
If we find life on another world, it will be an extremely important discovery and we will have to take great care not to do anything that might endanger that life. If the life we find is sentient we will have moral [...] Read more.
If we find life on another world, it will be an extremely important discovery and we will have to take great care not to do anything that might endanger that life. If the life we find is sentient we will have moral obligations to that life. Whether it is sentient or not, we have a duty to ourselves to preserve it as a study object, and also because it would be commonly seen as valuable in its own right. In addition to this we would also have a duty to our fellow humans and other earthly life forms not to expose them to danger by advertently or inadvertently exposing them to potentially harmful space organisms. When space exploration turns into exploitation it will therefore be important to be able to show that a world that is up for exploitation is uninhabited before the exploitation starts. Showing that a world is uninhabited is, however, a different kind of task than showing that it is inhabited. The latter task can be accomplished through one positive finding but it is not clear how to go about the former task. In this paper I suggest that it is a gradual process asymptotically approaching certainty rather than a discovery in the traditional sense of the word. It has to be handled in two steps. The first is to connect degree of certainty with research setup. The second is to decide how certain we need to be. The first step is about the number, diversity and quality of observations. The second step is a decision we have to make based on the purpose of the investigation. The purpose and therefore the degree of certainty needed to establish that a world is uninhabited will be different for a world that is up for exploitation than for a world that is not. In the latter case it is only a matter of epistemic values. In the former case also ethical values have to be considered. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessArticle The Art of Interconnected Thinking: Starting with the Young
Challenges 2014, 5(2), 239-259; doi:10.3390/challe5020239
Received: 28 May 2014 / Revised: 4 July 2014 / Accepted: 7 August 2014 / Published: 18 August 2014
Cited by 4 | PDF Full-text (938 KB) | HTML Full-text | XML Full-text
Abstract
Despite many efforts to deal with the various complex issues facing our societies, plans and problem solutions are seldom long lasting, because we, as individuals, and our leaders are most likely to fall into the trap of using traditional linear thinking. It [...] Read more.
Despite many efforts to deal with the various complex issues facing our societies, plans and problem solutions are seldom long lasting, because we, as individuals, and our leaders are most likely to fall into the trap of using traditional linear thinking. It is natural and easy, but does not usually deliver long-term solutions in the context of highly complex modern communities. There is an urgent need for innovative ways of thinking and a fresh approach to dealing with the unprecedented and complex challenges facing our world. It is essential for future leaders and citizens to be prepared for “interconnected” thinking to deal with complex problems in a systemic, integrated and collaborative fashion; working together to deal with issues holistically, rather than simplistically focusing on isolated features. An educational tool (Ecopolicy) is used as the main mechanism to achieve this aim. The Ecopolicy cybernetic simulation “game” is a challenging, but playful, method by which students are introduced to the idea of thinking in terms of relations, in feedback cycles, in networks and in systems. Participation in this stimulating simulation enhances the capacity of young people to change their way of thinking. This would be expected to prepare them to develop into leaders or citizens who can effectively deal with a complex and challenging future. Full article
Open AccessArticle On the Habitability of Aquaplanets
Challenges 2014, 5(2), 284-293; doi:10.3390/challe5020284
Received: 29 May 2014 / Revised: 18 August 2014 / Accepted: 20 August 2014 / Published: 28 August 2014
PDF Full-text (239 KB) | HTML Full-text | XML Full-text
Abstract
An Aquatic Habitability Index is proposed, based on Quantitative Habitability Theory, and considering a very general model for life. It is a primary habitability index, measuring habitability for phytoplankton in the first place. The index is applied to some case studies, such [...] Read more.
An Aquatic Habitability Index is proposed, based on Quantitative Habitability Theory, and considering a very general model for life. It is a primary habitability index, measuring habitability for phytoplankton in the first place. The index is applied to some case studies, such as the habitability changes in Earth due to environmental perturbations caused by asteroid impacts. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessArticle Towards a Mathematical Description of Biodiversity Evolution
Challenges 2014, 5(2), 324-333; doi:10.3390/challe5020324
Received: 24 June 2014 / Revised: 21 August 2014 / Accepted: 12 September 2014 / Published: 23 September 2014
PDF Full-text (389 KB) | HTML Full-text | XML Full-text
Abstract
We outline in this work a mathematical description of biodiversity evolution based on a second-order differential equation (also known as the “inertial/Galilean view”). After discussing the motivations and explicit forms of the simplest “forces”, we are lead to an equation analogue to [...] Read more.
We outline in this work a mathematical description of biodiversity evolution based on a second-order differential equation (also known as the “inertial/Galilean view”). After discussing the motivations and explicit forms of the simplest “forces”, we are lead to an equation analogue to a harmonic oscillator. The known solutions for the homogeneous problem are then tentatively related to the biodiversity curves of Sepkoski and Alroy et al., suggesting mostly an inertial behavior of the time evolution of the number of genera and a quadratic behavior in some long-term evolution after extinction events. We present the Green function for the dynamical system and apply it to the description of the recovery curve after the Permo-Triassic extinction, as recently analyzed by Burgess, Bowring and Shen. Even though the agreement is not satisfactory, we point out direct connections between observed drop times after massive extinctions and mathematical constants and discuss why the failure ensues, suggesting a more complex form of the second-order mathematical description. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessCommunication MyChEMBL: A Virtual Platform for Distributing Cheminformatics Tools and Open Data
Challenges 2014, 5(2), 334-337; doi:10.3390/challe5020334
Received: 14 August 2014 / Revised: 22 September 2014 / Accepted: 24 September 2014 / Published: 29 September 2014
Cited by 4 | PDF Full-text (177 KB) | HTML Full-text | XML Full-text
Abstract
MyChEMBL is an open virtual platform which provides a free, secure, standardised and easy to use chemoinformatics environment for bioactivity data mining, machine learning, application development, learning and teaching. The main technical features of myChEMBL along with its applications and future plans [...] Read more.
MyChEMBL is an open virtual platform which provides a free, secure, standardised and easy to use chemoinformatics environment for bioactivity data mining, machine learning, application development, learning and teaching. The main technical features of myChEMBL along with its applications and future plans are discussed here. Full article
Open AccessArticle Forest Biomass for Energy Production: Perceptions of State Forestry Professionals from China and India
Challenges 2014, 5(2), 338-350; doi:10.3390/challe5020338
Received: 14 July 2014 / Revised: 12 September 2014 / Accepted: 8 October 2014 / Published: 16 October 2014
Cited by 1 | PDF Full-text (298 KB) | HTML Full-text | XML Full-text
Abstract
This study investigated perceptions of a group of Chinese and Indian state forestry professionals (SFPs) related to the potential benefits and challenges of developing forest-based bioenergy projects (FBPs) in their countries. A total of 110 SFPs participated in the study (55 from [...] Read more.
This study investigated perceptions of a group of Chinese and Indian state forestry professionals (SFPs) related to the potential benefits and challenges of developing forest-based bioenergy projects (FBPs) in their countries. A total of 110 SFPs participated in the study (55 from each country). The results showed that the SFPs widely agreed upon the potential economic and ecological benefits from developing FBPs in their countries. The economic benefits of job creation and additional income to forest departments were the two most accepted benefits by the SFPs. Two potential challenges of developing FBPs—namely, the lack of suitable technologies and the absence of supportive policies—were considered the most significant by the SFPs. Principal component analysis revealed three key dimensions (ecological, economic and social) of the SFPs’ perceptions of FBPs. The findings from the study imply that in order to become viable, the development of FBPs in these two countries must put emphasis on the sustainability aspects by addressing the environmental, economic and societal elements of FBPs. In addition, framing supportive policies, the development of technologies and building infrastructure for FBPs are needed for their successful implementation in China and India. Full article
(This article belongs to the Special Issue Bioenergy in the BRICS Countries)
Open AccessArticle The Radiation Environment of Exoplanet Atmospheres
Challenges 2014, 5(2), 351-373; doi:10.3390/challe5020351
Received: 15 August 2014 / Revised: 2 October 2014 / Accepted: 10 October 2014 / Published: 29 October 2014
PDF Full-text (788 KB) | HTML Full-text | XML Full-text
Abstract
Exoplanets are born and evolve in the radiation and particle environment created by their host star. The host star’s optical and infrared radiation heats the exoplanet’s lower atmosphere and surface, while the ultraviolet, extreme ultraviolet and X-radiation control the photochemistry and mass [...] Read more.
Exoplanets are born and evolve in the radiation and particle environment created by their host star. The host star’s optical and infrared radiation heats the exoplanet’s lower atmosphere and surface, while the ultraviolet, extreme ultraviolet and X-radiation control the photochemistry and mass loss from the exoplanet’s upper atmosphere. Stellar radiation, especially at the shorter wavelengths, changes dramatically as a host star evolves leading to changes in the planet’s atmosphere and habitability. This paper reviews the present state of our knowledge concerning the time-dependent radiation emitted by stars with convective zones, that is stars with spectral types F, G, K, and M, which comprise nearly all of the host stars of detected exoplanets. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessArticle The Wickedness and Complexity of Decision Making in Geoengineering
Challenges 2014, 5(2), 390-408; doi:10.3390/challe5020390
Received: 26 May 2014 / Revised: 29 October 2014 / Accepted: 30 October 2014 / Published: 6 November 2014
Cited by 1 | PDF Full-text (384 KB) | HTML Full-text | XML Full-text
Abstract
Geoengineering, the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change, has been more widely considered as an accompanying strategy to conventional climate change mitigation measures to combat global warming. However, this approach is far from achieving agreements from [...] Read more.
Geoengineering, the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change, has been more widely considered as an accompanying strategy to conventional climate change mitigation measures to combat global warming. However, this approach is far from achieving agreements from different institutional domains. Geoengineering, intended to be deployed on a planetary scale, would cause fundamental interventions to the human-environment system and create new risks and problems with high uncertainty and uneven distribution around the globe. Apart from the physical effects, conflicting attitudes appear from social, economic, and environmental worldviews in the international community. The intertwined sociotechnical complexity and conflicting attitudes make geoengineering a wicked and complex issue. This article elaborates the wickedness and complexity from a system perspective, primarily for an interdisciplinary, policy-oriented audience. Full article
Open AccessArticle To Which Degree Does Sector Specific Standardization Make Life Cycle Assessments Comparable?—The Case of Global Warming Potential of Smartphones
Challenges 2014, 5(2), 409-429; doi:10.3390/challe5020409
Received: 3 August 2014 / Revised: 28 September 2014 / Accepted: 28 September 2014 / Published: 7 November 2014
Cited by 8 | PDF Full-text (774 KB) | HTML Full-text | XML Full-text
Abstract
Here attributional life cycle assessments (LCAs) for the same smartphone model are presented by two different organizations (Orange, OGE and Huawei, HuW) and the effect of different modeling approach is analyzed. A difference of around 32% (29.6 kg and 39.2 kg) for [...] Read more.
Here attributional life cycle assessments (LCAs) for the same smartphone model are presented by two different organizations (Orange, OGE and Huawei, HuW) and the effect of different modeling approach is analyzed. A difference of around 32% (29.6 kg and 39.2 kg) for CO2e baseline scores is found using same study object and sector specific LCA standard, however, different metrics, emission intensities, and LCA software programs. The CO2e difference is reduced to 12% (29.9 kg and 33.5 kg) when OGE use HuW metrics for use phase power consumption and total mass, and when HuW use OGE metrics for gold mass and silicon die area. Further, a probability test confirms that present baseline climate change results, for one specific study object modeled with two largely different and independent LCA modeling approaches, are comparable if both use the European Telecommunications Standard Institute (ETSI) LCA standard. The general conclusion is that the ETSI LCA standard strongly facilitates comparable CC results for technically comparable smartphone models. Moreover, thanks to the reporting requirements of ETSI LCA standard, a clear understanding of the differences between LCA modeling approaches is obtained. The research also discusses the magnitude of the CO2e reduction potential in the life cycle of smartphones. Full article
Open AccessArticle How Do Modern Extreme Hydrothermal Environments Inform the Identification of Martian Habitability? The Case of the El Tatio Geyser Field
Challenges 2014, 5(2), 430-443; doi:10.3390/challe5020430
Received: 26 August 2014 / Revised: 27 October 2014 / Accepted: 3 November 2014 / Published: 13 November 2014
PDF Full-text (390 KB) | HTML Full-text | XML Full-text
Abstract
Despite the success in knowledge gained by the Mars missions in the last two decades, the search for traces of life on Mars is still in progress. The reconstruction of (paleo-) environments on Mars have seen a dramatic increase, in particular with [...] Read more.
Despite the success in knowledge gained by the Mars missions in the last two decades, the search for traces of life on Mars is still in progress. The reconstruction of (paleo-) environments on Mars have seen a dramatic increase, in particular with regard to the potentially habitable conditions, and it is now possible to recognize a significant role to subaerial hydrothermal processes. For this reason, and because the conditions of the primordial Earth—when these extreme environments had to be common—probably resembled Mars during its most suitable time to host life, research on terrestrial extreme hydrothermal habitats may assist in understanding how to recognize life on Mars. A number of geological and environmental reasons, and logistics opportunities, make the geothermal field of El Tatio, in the Chilean Andes an ideal location to study. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessCommunication ChEMBL Beaker: A Lightweight Web Framework Providing Robust and Extensible Cheminformatics Services
Challenges 2014, 5(2), 444-449; doi:10.3390/challe5020444
Received: 18 August 2014 / Revised: 29 October 2014 / Accepted: 5 November 2014 / Published: 17 November 2014
Cited by 2 | PDF Full-text (184 KB) | HTML Full-text | XML Full-text
Abstract ChEMBL Beaker is an open source web framework, exposing a versatile chemistry-focused API (Application Programming Interface) to support the development of new cheminformatics applications. This paper describes the current functionality offered by Beaker and outlines the future technology roadmap. Full article
Open AccessCommunication An Evolutionary Optimizer of libsvm Models
Challenges 2014, 5(2), 450-472; doi:10.3390/challe5020450
Received: 1 September 2014 / Revised: 27 October 2014 / Accepted: 29 October 2014 / Published: 24 November 2014
Cited by 7 | PDF Full-text (347 KB) | HTML Full-text | XML Full-text
Abstract
This user guide describes the rationale behind, and the modus operandi of a Unix script-driven package for evolutionary searching of optimal Support Vector Machine model parameters as computed by the libsvm package, leading to support vector machine models of maximal predictive power [...] Read more.
This user guide describes the rationale behind, and the modus operandi of a Unix script-driven package for evolutionary searching of optimal Support Vector Machine model parameters as computed by the libsvm package, leading to support vector machine models of maximal predictive power and robustness. Unlike common libsvm parameterizing engines, the current distribution includes the key choice of best-suited sets of attributes/descriptors, in addition to the classical libsvm operational parameters (kernel choice, kernel parameters, cost, and so forth), allowing a unified search in an enlarged problem space. It relies on an aggressive, repeated cross-validation scheme to ensure a rigorous assessment of model quality. Primarily designed for chemoinformatics applications, it also supports the inclusion of decoy instances, for which the explained property (bioactivity) is, strictly speaking, unknown but presumably “inactive”, thus additionally testing the robustness of a model to noise. The package was developed with parallel computing in mind, supporting execution on both multi-core workstations as well as compute cluster environments. It can be downloaded from http://infochim.u-strasbg.fr/spip.php?rubrique178. Full article
Open AccessArticle Optimisation of Storage for Concentrated Solar Power Plants
Challenges 2014, 5(2), 473-503; doi:10.3390/challe5020473
Received: 10 October 2014 / Revised: 1 December 2014 / Accepted: 2 December 2014 / Published: 12 December 2014
PDF Full-text (492 KB)
Abstract
The proliferation of non-scheduled generation from renewable electrical energy sources such concentrated solar power (CSP) presents a need for enabling scheduled generation by incorporating energy storage; either via directly coupled Thermal Energy Storage (TES) or Electrical Storage Systems (ESS) distributed within the [...] Read more.
The proliferation of non-scheduled generation from renewable electrical energy sources such concentrated solar power (CSP) presents a need for enabling scheduled generation by incorporating energy storage; either via directly coupled Thermal Energy Storage (TES) or Electrical Storage Systems (ESS) distributed within the electrical network or grid. The challenges for 100% renewable energy generation are: to minimise capitalisation cost and to maximise energy dispatch capacity. The aims of this review article are twofold: to review storage technologies and to survey the most appropriate optimisation techniques to determine optimal operation and size of storage of a system to operate in the Australian National Energy Market (NEM). Storage technologies are reviewed to establish indicative characterisations of energy density, conversion efficiency, charge/discharge rates and costings. A partitioning of optimisation techniques based on methods most appropriate for various time scales is performed: from “whole of year”, seasonal, monthly, weekly and daily averaging to those best suited matching the NEM bid timing of five minute dispatch bidding, averaged on the half hour as the trading settlement spot price. Finally, a selection of the most promising research directions and methods to determine the optimal operation and sizing of storage for renewables in the grid is presented. Full article

Review

Jump to: Research, Other

Open AccessReview Prebiotic Phosphorylation Reactions on the Early Earth
Challenges 2014, 5(2), 193-212; doi:10.3390/challe5020193
Received: 28 May 2014 / Revised: 19 June 2014 / Accepted: 9 July 2014 / Published: 18 July 2014
Cited by 2 | PDF Full-text (768 KB) | HTML Full-text | XML Full-text
Abstract
Phosphorus (P) is an essential element for life. It occurs in living beings in the form of phosphate, which is ubiquitous in biochemistry, chiefly in the form of C-O-P (carbon, oxygen and phosphorus), C-P, or P-O-P linkages to form life. Within prebiotic [...] Read more.
Phosphorus (P) is an essential element for life. It occurs in living beings in the form of phosphate, which is ubiquitous in biochemistry, chiefly in the form of C-O-P (carbon, oxygen and phosphorus), C-P, or P-O-P linkages to form life. Within prebiotic chemistry, several key questions concerning phosphorus chemistry have developed: what were the most likely sources of P on the early Earth? How did it become incorporated into the biological world to form the P compounds that life employs today? Can meteorites be responsible for the delivery of P? What were the most likely solvents on the early Earth and out of those which are favorable for phosphorylation? Or, alternatively, were P compounds most likely produced in relatively dry environments? What were the most suitable temperature conditions for phosphorylation? A route to efficient formation of biological P compounds is still a question that challenges astrobiologists. This article discusses these important issues related to the origin of biological P compounds. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Figures

Open AccessReview Biogenicity and Syngeneity of Organic Matter in Ancient Sedimentary Rocks: Recent Advances in the Search for Evidence of Past Life
Challenges 2014, 5(2), 260-283; doi:10.3390/challe5020260
Received: 12 May 2014 / Revised: 20 August 2014 / Accepted: 21 August 2014 / Published: 27 August 2014
Cited by 3 | PDF Full-text (325 KB) | HTML Full-text | XML Full-text
Abstract
The past decade has seen an explosion of new technologies for assessment of biogenicity and syngeneity of carbonaceous material within sedimentary rocks. Advances have been made in techniques for analysis of in situ organic matter as well as for extracted bulk samples [...] Read more.
The past decade has seen an explosion of new technologies for assessment of biogenicity and syngeneity of carbonaceous material within sedimentary rocks. Advances have been made in techniques for analysis of in situ organic matter as well as for extracted bulk samples of soluble and insoluble (kerogen) organic fractions. The in situ techniques allow analysis of micrometer-to-sub-micrometer-scale organic residues within their host rocks and include Raman and fluorescence spectroscopy/imagery, confocal laser scanning microscopy, and forms of secondary ion/laser-based mass spectrometry, analytical transmission electron microscopy, and X-ray absorption microscopy/spectroscopy. Analyses can be made for chemical, molecular, and isotopic composition coupled with assessment of spatial relationships to surrounding minerals, veins, and fractures. The bulk analyses include improved methods for minimizing contamination and recognizing syngenetic constituents of soluble organic fractions as well as enhanced spectroscopic and pyrolytic techniques for unlocking syngenetic molecular signatures in kerogen. Together, these technologies provide vital tools for the study of some of the oldest and problematic carbonaceous residues and for advancing our understanding of the earliest stages of biological evolution on Earth and the search for evidence of life beyond Earth. We discuss each of these new technologies, emphasizing their advantages and disadvantages, applications, and likely future directions. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessReview The Detection and Characterization of Extrasolar Planets
Challenges 2014, 5(2), 296-323; doi:10.3390/challe5020296
Received: 1 July 2014 / Revised: 3 September 2014 / Accepted: 3 September 2014 / Published: 19 September 2014
Cited by 1 | PDF Full-text (9924 KB) | HTML Full-text | XML Full-text
Abstract
We have now confirmed the existence of > 1800 planets orbiting stars other thanthe Sun; known as extrasolar planets or exoplanets. The different methods for detectingsuch planets are sensitive to different regions of parameter space, and so, we are discoveringa wide diversity [...] Read more.
We have now confirmed the existence of > 1800 planets orbiting stars other thanthe Sun; known as extrasolar planets or exoplanets. The different methods for detectingsuch planets are sensitive to different regions of parameter space, and so, we are discoveringa wide diversity of exoplanets and exoplanetary systems. Characterizing such planets isdifficult, but we are starting to be able to determine something of their internal compositionand are beginning to be able to probe their atmospheres, the first step towards the detectionof bio-signatures and, hence, determining if a planet could be habitable or not. Here, Iwill review how we detect exoplanets, how we characterize exoplanetary systems and theexoplanets themselves, where we stand with respect to potentially habitable planets and howwe are progressing towards being able to actually determine if a planet could host life or not. Full article
(This article belongs to the Special Issue Challenges in Astrobiology)
Open AccessReview Advances in Packaging Methods, Processes and Systems
Challenges 2014, 5(2), 374-389; doi:10.3390/challe5020374
Received: 30 June 2014 / Revised: 17 October 2014 / Accepted: 27 October 2014 / Published: 31 October 2014
PDF Full-text (808 KB) | HTML Full-text | XML Full-text
Abstract
The food processing and packaging industry is becoming a multi-trillion dollar global business. The reason is that the recent increase in incomes in traditionally less economically developed countries has led to a rise in standards of living that includes a significantly higher [...] Read more.
The food processing and packaging industry is becoming a multi-trillion dollar global business. The reason is that the recent increase in incomes in traditionally less economically developed countries has led to a rise in standards of living that includes a significantly higher consumption of packaged foods. As a result, food safety guidelines have been more stringent than ever. At the same time, the number of research and educational institutions—that is, the number of potential researchers and stakeholders—has increased in the recent past. This paper reviews recent developments in food processing and packaging (FPP), keeping in view the aforementioned advancements and bearing in mind that FPP is an interdisciplinary area in that materials, safety, systems, regulation, and supply chains play vital roles. In particular, the review covers processing and packaging principles, standards, interfaces, techniques, methods, and state-of-the-art technologies that are currently in use or in development. Recent advances such as smart packaging, non-destructive inspection methods, printing techniques, application of robotics and machineries, automation architecture, software systems and interfaces are reviewed. Full article

Other

Jump to: Research, Review

Open AccessTechnical Note jsGraph and jsNMR—Advanced Scientific Charting
Challenges 2014, 5(2), 294-295; doi:10.3390/challe5020294
Received: 1 September 2014 / Revised: 9 September 2014 / Accepted: 9 September 2014 / Published: 18 September 2014
Cited by 1 | PDF Full-text (148 KB) | HTML Full-text | XML Full-text
Abstract
The jsGraph library is a versatile javascript library that allows advanced charting to be rendered interactively in web browsers without relying on server-side image processing. jsGraph is released under the MIT license and is free of charge. While being highly customizable through [...] Read more.
The jsGraph library is a versatile javascript library that allows advanced charting to be rendered interactively in web browsers without relying on server-side image processing. jsGraph is released under the MIT license and is free of charge. While being highly customizable through an intuitive javascript API, jsGraph is optimized to render a large quantity of data in a short amount of time. jsGraphs can display line, scatter, contour or zone series. Examples can be consulted on the project home page [1]. Customization of the chart, its axis and its series is achieved through simple but comprehensive JSON configurations. Full article

Journal Contact

MDPI AG
Challenges Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
challenges@mdpi.com
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Challenges
Back to Top