La predicción de la demanda en evaluación de proyectos

La predicción de la demanda juega un papel clave en la evaluación de proyectos. Sin embargo, la evidencia reciente indica que la predicción a largo plazo está sujeta a fuertes incertidumbres. Este artículo discute algunos aspectos relevantes relacionados con la predicción de la demanda a largo plazo y, en especial, la incertidumbre. En primer lugar, el artículo revisa los principales aspectos que la predicción de la demanda debe tomar en consideración para evitar errores que pueden distorsionar los resultados de la evaluación. A continuación, se analiza de forma sucinta las ventajas e inconvenientes de los modelos de demanda a efectos de predicción, con especial referencia a la predicción a largo plazo y a la elección modal. En tercer lugar, se caracterizan los errores de predicción y se presenta como ejemplo ilustrativo el impacto de la incertidumbre en la predicción a largo plazo para una autopista de peaje. Por último, se resumen los modelos de predicción de la demanda aplicados en España.Demand forecasting is a key factor in project evaluation. However, according to recent empirical evidence, long-term predictions are subject to high levels of uncertainty. This paper discusses some relevant topics related to long run demand forecasting with special emphasis on uncertainty. Firstly, we offer a review of the main issues that demand forecasting should consider in order to avoid errors that might distort the result of the evaluation. Secondly, we analyze the pros and cons of alternative modelling approaches, particularly, long term forecast and modal split models. The paper goes on to describe the characteristics of the forecasting errors and provides, as an illustrative example, the impact of uncertainty on long term forecasting for a tolled motorway. Finally, we summarize the forecasting models used in Spain

ase-PoW: a proof of ownership mechanism for cloud deduplication in hierarchical environments

Proof-of-Ownership (PoW) can be an efective deduplication technique to reduce storage requirements, by providing cloud storage servers the capability to guarantee that clients only upload and download files that they are in possession of. In this paper, we propose an attribute symmetric encryption PoW scheme (ase-PoW) for hierarchical environments such as corporations, in which (1) the external cloud service provider is honest-but-curious and (2) there is a exible access control in place to ensure only users with the right privilege can access sensitive files. This is, to the best of our knowledge, the first such scheme and it is built upon the ce-PoW scheme of Gonzalez-Manzano and Orfila (2015). Ase-PoW outperforms ce-PoW in that it does not suffer from content-guessing attacks, it reduces client storage needs and computational workload.This work was partially supported by the MINECO grant TIN2013-46469-R (SPINY: Security and Privacy in the Internet of You) and the CAM grant S2013/ICE-3095 CIBERDINE-CM (CIBERDINE: Cybersecurity, Data, and Risks) funded by Madrid Autonomous Community and co-funded by European funds. L. Gonzalez and J. M. de Fuentes were also supported by the Programa de Ayudas para la Movilidad of Carlos III University of Madrid, Spain

Natural recovery of genetic diversity by gene flow in reforested areas of the endemic Canary Island pine, Pinus canariensis

The endemic pine, Pinus canariensis, forms one of the main forest ecosystems in the Canary Islands. In this archipelago, pine forest is a mosaic of natural stands (remnants of past forest overexploitation) and artificial stands planted from the 1940's. The genetic makeup of the artificially regenerated forest is of some concern. The use of reproductive material with uncontrolled origin or from a reduced number of parental trees may produce stands ill adapted to local conditions or unable to adapt in response to environmental change. The genetic diversity within a transect of reforested stands connecting two natural forest fragments has been studied with nuclear and chloroplast microsatellites. Little genetic differentiation and similar levels of genetic diversity to the surrounding natural stands were found for nuclear markers. However, chloroplast microsatellites presented lower haplotype diversity in reforested stands, and this may be a consequence of the lower effective population size of the chloroplast genome, meaning chloroplast markers have a higher sensitivity to bottlenecks. Understory natural regeneration within the reforestation was also analysed to study gene flow from natural forest into artificial stands. Estimates of immigration rate into artificially regenerated forest were high (0.68-0.75), producing a significant increase of genetic diversity (both in chloroplast and nuclear microsatellites), which indicates the capacity for genetic recovery for P. canariensis reforestations surrounded by larger natural stands

Optical continuum reverberation in the dwarf Seyfert nucleus of NGC 4395

Funding information: LCO telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by NSF. This Letter is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial supports by JSPS KAKENHI (JP18H05439) and JST PRESTO (JPMJPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. Research at UC Irvine was supported by NSF grant AST-1907290. D.H.G.-B. acknowledges CONACYT support #319800. J.V.H.S. acknowledges support from STFC grant ST/R000824/1.In order to constrain the size of the optical continuum emission region in the dwarf Seyfert 1 galaxy NGC 4395 through reverberation mapping, we carried out high-cadence photometric monitoring in the griz filter bands on two consecutive nights in 2022 April using the four-channel MuSCAT3 camera on the Faulkes Telescope North at Haleakalā Observatory. Correlated variability across the griz bands is clearly detected, and the r-, i-, and z-band light curves show lags of - + 7.72 +1.01 -1.09, 14.16 +1.22-1.25, and 20.78  +1.99-2.09 minutes with respect to the g band when measured using the full-duration light curves. When lags are measured for each night separately, the Night 2 data exhibit lower cross-correlation amplitudes and shorter lags than the Night 1 light curves. Using the full-duration lags, we find that the lag–wavelength relationship is consistent with the τ ∝ λ4/3 dependence found for more luminous active galactic nuclei. Combining our results with continuum lags measured for other objects, the lag between g and z band scales with optical continuum luminosity as τgz ∝ L0.56±0.05, similar to the scaling of broad-line region size with luminosity, reinforcing recent evidence that diffuse continuum emission from the broad-line region may contribute substantially to optical continuum variability and reverberation lags.Publisher PDFPeer reviewe

Editorial: Security and privacy in Internet of Things

J. M. de Fuentes, L. Gonzalez-Manzano and P. Peris-Lopez have been partially supported by MINECO grants TIN2013-46469-R and TIN2016-79095-C2-2-R, and CAM grant S2013/ICE-3095

Accelerated hardening of nanotextured 3D-plotted self-setting calcium phosphate inks

Direct ink writing (DIW) techniques open up new possibilities for the fabrication of patient-specific bone grafts. Self-setting calcium phosphate inks, which harden at low temperature, allow obtaining nanostructured scaffolds with biomimetic properties and enhanced bioactivity. However, the slow hardening kinetics hampers the translation to the clinics. Different hydrothermal treatments for the consolidation of DIW scaffolds fabricated with an a-tricalcium phosphate /pluronic F127 ink were explored, comparing them with a biomimetic treatment. Three different scaffold architectures were analysed. The hardening process, associated to the conversion of a-tricalcium phosphate to hydroxyapatite was drastically accelerated by the hydrothermal treatments, reducing the time for complete reaction from 7¿days to 30 minutes, while preserving the scaffold architectural integrity and retaining the nanostructured features. ß-tricalcium phosphate was formed as a secondary phase, and a change of morphology from plate-like to needle-like crystals in the hydroxyapatite phase was observed. The binder was largely released during the treatment. The hydrothermal treatment resulted in a 30% reduction of the compressive strength, associated to the residual presence of ß-tricalcium phosphate. Biomimetic and hydrothermally treated scaffolds supported the adhesion and proliferation of rat mesenchymal stem cells, indicating a good suitability for bone tissue engineering applications. Statement of Significance 3D plotting has opened up new perspectives in the bone regeneration field allowing the customisation of synthetic bone grafts able to fit patient-specific bone defects. Moreover, this technique allows the control of the scaffolds’ architecture and porosity. The present work introduces a new method to harden biomimetic hydroxyapatite 3D-plotted scaffolds which avoids high-temperature sintering. It has two main advantages: i) it is fast and simple, reducing the whole fabrication process from the several days required for the biomimetic processing to a few hours; and ii) it retains the nanostructured character of biomimetic hydroxyapatite and allows controlling the porosity from the nano- to the macroscale. Moreover, the good in vitro cytocompatibility results support its suitability for cell-based bone regeneration therapiesPeer ReviewedPostprint (author's final draft

Characterization of six microsatellite loci in Myrica faya (Myricaceae) and cross amplification in the endangered endemic M. rivas-martinezii in Canary Islands, Spain

Six novel polymorphic microsatellite markers were isolated from enriched libraries in Myrica faya Ait., recently renamed Morella faya, (fayatree, firetree, or firebush) in order to examine the genetic diversity in natural populations. Also, test cross-specific amplification and genetic diversity in Myrica rivas-martinezii, which is endemic on the Canary islands. Microsatellite loci were screened in 225 individuals of both species from different islands of the Canarian archipelago. All markers were successfully amplified from both Myrica species, with an average number of 6.5 and 9.3 alleles per locus in M. rivas-martinezii and M. faya, respectively. There was no evidence for linkage disequilibrium between loci, and the probability of null alleles ranged from 0.01 to 0.17

Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus

Coastal lagoons are semi-isolated ecosystems exposed to wide fluctuations of environmental conditions and showing habitat fragmentation. These features may play an important role in separating species into different populations, even at small spatial scales. In this study, we evaluate the concordance between mitochondrial (previous published data) and nuclear data analyzing the genetic variability of Pomatoschistus marmoratus in five localities, inside and outside the Mar Menor coastal lagoon (SE Spain) using eight microsatellites. High genetic diversity and similar levels of allele richness were observed across all loci and localities, although significant genic and genotypic differentiation was found between populations inside and outside the lagoon. In contrast to the FST values obtained from previous mitochondrial DNA analyses (control region), the microsatellite data exhibited significant differentiation among samples inside the Mar Menor and between lagoonal and marine samples. This pattern was corroborated using Cavalli-Sforza genetic distances. The habitat fragmentation inside the coastal lagoon and among lagoon and marine localities could be acting as a barrier to gene flow and contributing to the observed genetic structure. Our results from generalized additive models point a significant link between extreme lagoonal environmental conditions (mainly maximum salinity) and P. marmoratus genetic composition. Thereby, these environmental features could be also acting on genetic structure of coastal lagoon populations of P. marmoratus favoring their genetic divergence. The mating strategy of P. marmoratus could be also influencing our results obtained from mitochondrial and nuclear DNA. Therefore, a special consideration must be done in the selection of the DNA markers depending on the reproductive strategy of the species

The anti-correlation between the hard X-ray photon index and the Eddington ratio in LLAGNs

We find a significant anti-correlation between the hard X-ray photon index and the Eddington ratio L_Bol/L_Edd for a sample of Low-Ionization Nuclear Emission-line Regions (LINERs) and local Seyfert galaxies, compiled from literatures with Chandra or XMM-Newton observations. This result is in contrast with the positive correlation found in luminous active galactic nuclei (AGNs), while it is similar to that of X-ray binaries (XRBs) in low/hard state. Our result is qualitatively consistent with the spectra produced from advection dominated accretion flows (ADAFs). It implies that the X-ray emission of low-luminosity active galactic nuclei (LLAGNs) may originate from the Comptonization process in ADAF, and the accretion process in LLAGNs may be similar to that of XRBs in the low/hard state, which is different from that in luminous AGNs.Comment: 10 pages, 1 figure, accepted to MNRA

Making space for cultural ecosystem services: insights from a study of the UK Nature Improvement Initiative

A study of the cultural ecosystem services (CES) arising from peoples’ interactions with the rural environment is conducted within the context of a landscape scale, ‘nature improvement’ initiative in the United Kingdom. Taking a mixed methodological approach, the research applies, and demonstrates empirically, a framework for CES developed under the UK National Ecosystem Assessment (Fish et al., 2016). Applications of the framework involve the study of the ‘environmental spaces’ and ‘cultural practices’ that contribute to the realisation of benefits to well-being. In this paper empirical work is undertaken to inform the CES evidence base informing management priorities of the Northern Devon Nature Improvement Area (NDNIA) in south west England. Findings from a questionnaire survey, qualitative mapping, group discussion and a participatory arts-based research process are presented to document the many and diverse ways this study area matters to local communities. The paper analyses the qualities that research participants attribute to the environmental space of the NDNIA, the cultural practices conducted and enabled within it, and their associated benefits. The implications of the study for applying this framework through mixed methodological research are discussed, alongside an account of the impact of this approach within the NDNIA itself.This research was funded through the UK National Ecosystem Assessment Follow-On (Work Package 5: Cultural ecosystem services and indicators) funded by the UK Department of the Environment, Food and Rural Affairs (Defra), the Welsh Government, the UK Natural Environment Research Council (NERC), Economic and Social Research Council (ESRC), and Arts and Humanities Research Council (AHRC)