A new system to measure leather shrinkage temperature

Content: A characteristic of leather is that if it is gradually heated in aqueous solution it reaches a temperature where sudden and irreversible shrinkage occurs. This phenomenon is related to the denaturalization of the collagen protein that conforms the hide and is known as leather shrinkage. Specifically, the internal bonds break thus causing a shortening of the skin that can be up to a 35% from its original length. Accordingly, one of the most used methods to check the quality of the leather tanning process is the determination of the contraction temperature according to the ISO 3380:2015 standard. This method measures the leather shrinkage when constantly increasing the sample temperature. The shrinkage temperature corresponds to the temperature when the sample suddenly contracts. The value of this temperature indicates the degree of collagen stability and therefore, when higher, the leather will have better quality and resistance. The process of leather shrinkage can be divided in different stages. Several authors discriminate temperature A1 (when the first fibre starts to shrinkage), temperature C (when there is a massive shrinkage) and finally temperature A2 (when the last fibres are contracted individually). The method that describes the ISO 3380:2015 standard uses a device where the determination of the shrinkage temperature is performed visually by the laboratory technician. Consequently, the method tends to be imprecise and subjective. It should also be noticed that the device proposed by the standard does not allow differentiation between the different stages of the contraction process. There are other methods to determine leather shrinkage temperature including differential scanning calorimetry, microscopic hot table, thermogravimetric analysis, differential thermal analysis and thermomechanical analysis. All these methods involve complex devices and are only suitable for specialized personnel. In this work, a new device is developed to precisely measure the leather shrinkage temperature and to distinguish the different contraction stages. In addition, the proposed device is simple, easy to use and inexpensive, which facilitates its use in any industry. The developed system consists basically of a load cell to measure the strength produced by the shrinkage of the leather. With the logged data during the test a strength versus temperature graph is built. By means of its interpretation, the different stages of shrinkage can be determined. Different mathematical analysis of the logged data is proposed to determine the shrinkage stages temperatures, thus achieving a high degree of certainty and repeatability. Take-Away: A new device, simple and inexpensive, is developed to precisely measure the leather shrinkage temperature and to distinguish the different contraction stages

Late-time tails, entropy aspects, and stability of black holes with anisotropic fluids

In this work we consider black holes surrounded by anisotropic fluids in four dimensions. We first study the causal structure of these solutions showing some similarities and differences with Reissner-Nordstr\"om-de Sitter black holes. In addition, we consider scalar perturbations on this background geometry and compute the corresponding quasinormal modes. Moreover, we discuss the late-time behavior of the perturbations finding an interesting new feature, i.e., the presence of a subdominant power-law tail term. Likewise, we compute the Bekenstein entropy bound and the first semiclassical correction to the black hole entropy using the brick wall method, showing their universality. Finally, we also discuss the thermodynamical stability of the model.Comment: 23 pages, 4 figure

Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds

We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term. Using the modified Lichnerowicz equation we study the metric perturbations of Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to be published in JHE

Identification of iron in Earth analogues of Martian phyllosilicates using visible reflectance spectroscopy: Spectral derivatives and color parameters

A range of phyllosilicate compositions have been detected spectroscopically on Mars, but the largest fraction by far corresponds to clay minerals rich in Fe and Mg. Given that most of our understanding of Martian clays comes from remote sensing data, it is critically important to explore the details of how compositional variation affects spectral features of phyllosilicates. The greatest efforts have focused so far on near-infrared (NIR) spectroscopy. Recently, ambiguities have been detected in the NIR spectra of 2:1 phyllosilicates with intermediate FeeMg content that preclude mineral and chemical discrimination. Such ambiguities highlight the relevance of exploring the visible spectral range as a complementary tool to characterize Martian phyllosilicates precisely. This article reports the investigation of laboratory reflectance spectra (330–800 nm) from 34 Earth analogues of Martian phyllosilicates with a wide range of MgeFe composition, including nontronite, celadonite and saponite end-members, as well as interstratified glauconite-nontronite, talc-nontronite, and talc-saponite. The spectra indicated the presence of Fe(III) by absorption modulations and a decrease in total reflectance, especially in samples with tetrahedral Fe(III). Absorption bands at 370 and 420 nm were diagnostic of octahedrically and tetrahedrally coordinated Fe(III), respectively. Band amplitudes in the second derivative of the Kubelka-Munk function correlated positively with Fe(III) content (R2 > 0.8). Standard color analyses of the visible reflectance spectra under the CIE illuminant D65 indicated that the CIELAB color parameter a*10 was positively correlated with tetrahedral Fe(III), b*10 was positively correlated with octahedral Fe(III), and L*10 was negatively correlated with Fe(III) in both structural sites. Because Fe(II) was in relatively low amount, it did not provide clear spectral evidence. Multiple regression models using the amplitude of the diagnostic absorption bands predicted well absolute Fe content in the phyllosilicates (R2=0.89) and the ratio Fe/(Fe+Mg+Al) (R2=0.84). CIELAB color parameters improved the prediction of total Fe (R2=0.92) and the ratio Fe/(Fe+Mg+Al) (R2=0.93). Application of these analyses to Martian data has challenges set by Fe oxide dust coating and spatial and spectral resolution. However, these results mark an avenue to develop testable tools using visible-wavelength spectral data from both satellite and lander probes to help establishing Fe content and mineral identification of Martian phyllosilicates

Limited rigor in studies of raptor mortality and mitigation at wind power facilities

Wind power is an expanding source of renewable energy. However, there are ecological challenges related to wind energy generation, including collisions of wildlife with turbines. Lack of rigor, and variation in study design, together limit efforts to understand the broad-scale effects of wind power infrastructure on wildlife populations. It is not clear, however, whether these types of limitations apply to groups of birds such as raptors that are particularly vulnerable to negative effects of wind energy. We reviewed 672 peer-reviewed publications, unpublished reports, and citations from 321 wind facilities in 12 countries to evaluate methods used to monitor and mitigate for wind facility impacts on raptors. Most reports that included raptor monitoring (86 %, n = 461) only conducted post-construction monitoring for raptor fatalities, while few (12 %; n = 65) estimated preconstruction raptor use. Only 27 % of facilities (n = 62) provided estimates of fatalities or raptor use across multiple construction phases, and the percentage of facilities with data available from multiple construction periods has not changed over time. A formal experimental study design was incorporated into surveys at only 29 % of facilities. Finally, mitigation practices to reduce impacts on raptors were only reported at 23 % of facilities. Our results suggest that rigorous data collection on wind energy impacts to raptors is rare, and that mitigation of detrimental effects is seldom reported. Expanding the use of rigorous research approaches and increasing data availability would improve understanding of the regional and global effects of wind energy on raptor populations

A framework for interpreting experimental errors in VISIR

Students usually do errors while performing experiments. In traditional, hands-on labs, instructors are able to help students surpass those errors. In non-traditional labs, like virtual labs or simulations, the support is usually provided by built-in mechanisms that prevent erroneous actions or that provide some sort of online assistance. In remote labs, like the Virtual Instruments Systems in Reality (VISIR) remote lab, the same principle applies. This paper describes the very initial stage of a framework for interpreting experimental errors done in VISIR. It considers the course syllabus of electrical circuits and situates the work done till the moment, in relation to that syllabus. Future work is also addressed.Partially supported by the European Commission, through grant 561735-EPP-1-2015-1-PT-EPPKA2-CBHE-JP, and by the Foundation for Science and Technology Project, FCT UID/EQU/04730/2013.info:eu-repo/semantics/publishedVersio

EyeArt + EyePACS: Automated Retinal Image Analysis For Diabetic Retinopathy Screening in a Telemedicine System

Telemedicine frameworks are key to screening the large, ever-growing diabetic population for preventable blindness due to diabetic retinopathy (DR). Integrating fully-automated screening systems in telemedicine frameworks will make DR screening more efficient, cost-effective, reproducible, and accessible. In this paper, we present the integration of EyeArt, an automated DR screening system, into EyePACS, a telemedicine system for DR screening used in diverse screening settings. EyeArt in- corporates novel image processing and analysis algorithms for assessing image gradability; enhancing images based on median filtering; detecting interest regions and localizing lesions based on multi-scale morphological analysis; and DR screening and thus achieves robustness to the large image variability seen in a telemedicine system such as EyePACS. EyeArt is implemented as a scalable, high-throughput cloud-based system to enable large-scale DR screening. We evaluate the safety and performance of EyeArt on a dataset with 434,023 images from 54,324 patient cases obtained from EyePACS. On this dataset, EyeArt’s screening sensitivity is 90% at specificity 60.8% and the area under the receiver operating characteristic curve (AUROC) is 0.883. In a setup where trained human graders review patient cases recommended for referral by EyeArt with low confidence, a workload reduction of 62% is possible. Therefore, EyeArt can be safely integrated into large real world telemedicine DR screening programs such as EyePACS helping reduce workload and increase efficiency and thus help in reducing vision loss due to DR through early detection and treatment

Thermal one- and two-graviton Green's functions in the temporal gauge

The thermal one- and two-graviton Green's function are computed using a temporal gauge. In order to handle the extra poles which are present in the propagator, we employ an ambiguity-free technique in the imaginary-time formalism. For temperatures T high compared with the external momentum, we obtain the leading T^4 as well as the subleading T^2 and log(T) contributions to the graviton self-energy. The gauge fixing independence of the leading T^4 terms as well as the Ward identity relating the self-energy with the one-point function are explicitly verified. We also verify the 't Hooft identities for the subleading T^2 terms and show that the logarithmic part has the same structure as the residue of the ultraviolet pole of the zero temperature graviton self-energy. We explicitly compute the extra terms generated by the prescription poles and verify that they do not change the behavior of the leading and sub-leading contributions from the hard thermal loop region. We discuss the modification of the solutions of the dispersion relations in the graviton plasma induced by the subleading T^2 contributions.Comment: 17 pages, 5 figures. Revised version to be published in Phys. Rev.