Multiplicative deconvolution under unknown error distribution

We consider a multiplicative deconvolution problem, in which the density $f$ or the survival function $S^X$ of a strictly positive random variable $X$ is estimated nonparametrically based on an i.i.d. sample from a noisy observation $Y = X\cdot U$ of $X$. The multiplicative measurement error $U$ is supposed to be independent of $X$. The objective of this work is to construct a fully data-driven estimation procedure when the error density $f^U$ is unknown. We assume that in addition to the i.i.d. sample from $Y$, we have at our disposal an additional i.i.d. sample drawn independently from the error distribution. The proposed estimation procedure combines the estimation of the Mellin transformation of the density $f$ and a regularisation of the inverse of the Mellin transform by a spectral cut-off. The derived risk bounds and oracle-type inequalities cover both - the estimation of the density $f$ as well as the survival function $S^X$. The main issue addressed in this work is the data-driven choice of the cut-off parameter using a model selection approach. We discuss conditions under which the fully data-driven estimator can attain the oracle-risk up to a constant without any previous knowledge of the error distribution. We compute convergences rates under classical smoothness assumptions. We illustrate the estimation strategy by a simulation study with different choices of distributions

Eutectic solvents for the valorisation of the aqueous phase from hydrothermally liquefied black liquor

The potential valorisation of the aqueous phase obtained after the hydrothermal liquefaction of Kraft black liquor by means of liquid-liquid extraction with new generation solvents was analysed for the first time ever. For this purpose, hydrophobic eutectic solvents (ES), based on combinations of menthol or thymol with octanoic, decanoic or dodecanoic acid, were tested to recover phenolic compounds from this wastewater. All of them showed high affinity for phenolic compounds and ethanol, but low affinity for the rest of the compounds, leaving a more biodegradable raffinate. Regarding phenolic compounds, the average extraction yields ranged from 66% to 91% with menthol-based ES and from 34% to 98% with thymol-based ES. The best solvent in terms of recovery and selectivity for phenolic compounds was 1:1 Menthol:Octanoic acid, with separation factors of 104.2 and 29.2 for phenolic compounds to volatile fatty acids and alcohols, respectively. In this regard, the results obtained open the simultaneous valorisation of the extract as a source of phenolic compounds, regenerating the ES, and the raffinate as a sustainable feedstock for further fermentation or catalytic processes

Revisión taxonómica del género Hypseocharis en Perú y Bolivia

In the present study we revised the genus Hypseocharis in Bolivia and Peru. A total number of 105 herbarium specimens were revised to evaluate the morphological diversity across the range of the genus. In a subset of 24 complete individuals a multivariate morphometric analysis was performed to evaluate the morphological characters historically used to differentiate the “species” of the genus Hypseocharis. A revision of the herbarium material indicated that there are no sharp lines dividing the different “species” with the only exception of H. tridentata. The multivariate analysis indicated that H. bilobata, H. malpasensis and H. pedicularifolia all occupy the same morphospace as H. pimpinellifolia and there are no individual morphological characters or suites of characters permitting the differentiation of distinct taxa. This confirms earlier findings from Argentina: There are only two species in the genus, widespread Hypseocharis pimpinellifolia and H. tridentata. Hypseocharis pilgeri, originally described from Peru, can also not be differentiated from H. pimpinellifolia. We propose the recognition of only two species: H. pimpinellifolia with variously pinnate to bipinnate leaves with a terminal leaflet at most marginally larger than the lateral ones, flowers with 15 anthers and capsular fruits as differing from H. tridentata with pinnate leaves with the terminal leaflet much larger than the lateral ones, flowers with 5 anthers and schizocarpic fruits. Hypseocharis pimpinellifolia is a widespread and polymorphic species, ranging from Ancash (Peru) to La Rioja (Argentina) and comprises forms with white, yellow, orange, and red corollas and with simply pinnate to very finely bipinnate leaves.En el presente estudio se realizó una revisión taxonómica del género Hypseocharis en Bolivia y Perú. Se analizó la diversidad morfológica abarcando toda la distribución geográfica del género Hypseocharis utilizando 105 especímenes de herbario. Un análisis multivariado morfométrico fue aplicado a 24 individuos completos para evaluar los caracteres históricos utilizados para diferenciar las especies dentro del género. La revisión del material de herbario mostró una distinción de la especie H. tridentata, pero no se confirmó una clara separación entre las “especies” H. bilobata, H. malpasensis, H. pedicularifolia y H. pimpinellifolia. Todas ocupan el mismo morfo espacio con similares caracteres morfológicos, apoyando previos estudios en Argentina, donde solamente se describieron dos especies: H. pimpinellifolia y H. tridentata, esta última proveniente de Argentina y con solo un espécimen de Bolivia. Nuestros resultados también mostraron que H. pilgeri, originalmente descrita en Perú, tampoco se diferencia de H. pimpinellifolia. Por lo tanto, proponemos la distinción de solamente dos especies en el género: H. pimipinellifolia con hojas variables pinnadas o bipinnadas, con foliolos terminales un poco más grandes que los foliolos laterales; flores con 15 anteras y tipo de fruto capsular. Mientras que H. tridentata posee hojas pinnadas con foliolos terminales mucho más grandes que los laterales; flores con 5 anteras y tipo de fruto esquizocarpo. Hypseocharis pimpinellifolia es una especie ampliamente distribuida desde Ancash (Perú) hasta La Rioja (Argentina) morfológicamente variable incluyendo varios tipos de hojas, desde simples pinnadas hasta bipinnadas y flores blancas, amarillas, naranjas o rojas

Valorisation of the residual aqueous phase from hydrothermally liquefied black liquor by persulphate-based advanced oxidation

Hydrothermal liquefaction of Kraft black liquor is a promising method for the production of valuable organic chemicals. However, the separation of the biochar and biocrude leaves a residual aqueous phase in large volumes, which needs to be properly managed to make the process profitable. In this work, the persulphate-based advanced oxidation was assessed, for the first time ever, as a pretreatment of this aqueous phase to reduce its content of phenolic compounds and alcohols, which hinder further valorisation strategies. Results revealed that the phenolic compounds and the alcohols were oxidised in presence of low persulphate anion concentrations (<50 mM), mainly to quinone-like compounds and organic acids. At higher oxidant concentrations, these intermediates were subsequently oxidised to valuable acetic acid. When Fe (II) was added as the catalyst, low concentrations (<9 mM) enhanced the degradation of both phenolic compounds and alcohols due to the increase of the sulphate radicals, consequently reducing persulphate requirements for their removal. Nevertheless, higher Fe (II) doses produced the sequestration of sulphate radicals, thus decreasing the oxidation performance and generating undesired parallel reactions

A Single Photon Avalanche Diode Array Fabricated in 0.35um CMOS and based on an Event-Driven Readout for TCSPC Experiments

The design and characterization of an imaging sensor based on single photon avalanche diodes is presented. The sensor was fully integrated in a 0.35µm CMOS technology. The core of the imager is an array of 4x112 pixels that independently and simultaneously detect the arrival time of photons with picosecond accuracy. A novel event-driven readout scheme allows parallel column-wise and non-sequential, on-demand row-wise operation. Both time-correlated and time-uncorrelated measurements are supported in the sensor. The readout scheme is scalable and requires only 11 transistors per pixel with a pitch of 25µm. A number of standard performance measurements for the imager are presented in the paper. An average dark count rate of 6Hz and 750Hz are reported at room temperature respectively for an active area diameter of 4µm and 10µm, while the dead time is 40ns with negligible crosstalk. A timing resolution better than 80ps over the entire integrated array makes this technique ideal for a fully integrated high resolution streak camera, thus enabling fast TCSPC experiments. Applications requiring low noise, picosecond timing accuracies, and measurement parallelism are prime candidates for this technology. Examples of such applications include bioimaging at cellular and molecular level based on fluorescence lifetime imaging and/or, fluorescence correlation spectroscopy, as well as fast optical imaging, optical rangefinders, LIDAR, and low light level imagers

Correction to: Improved X-ray baggage screening sensitivity with 'targetless' search training.

Funder: Defence and Security Accelerator; doi: http://dx.doi.org/10.13039/100012339Abstract: When searching for a known target, mental representations of target features, or templates, guide attention towards matching objects and facilitate recognition. When only distractor features are known, distractor templates allow irrelevant objects to be recognised and attention to be shifted away. This is particularly true in X-ray baggage search, a challenging real-world visual search task with implications for public safety, where targets may be unknown, difficult to predict and concealed by an adversary, but distractors are typically benign and easier to identify. In the present study, we draw on basic principles of distractor suppression and rejection to investigate a counterintuitive ‘targetless’ approach to training baggage search. In a simulated X-ray baggage search task, we observed significant benefits to target detection sensitivity (d′) for targetless relative to target-based training, but no effects of performance-contingent rewards or the inclusion of superordinate semantic categories during training. The benefits of targetless search training were most apparent for stimuli involving less spatial overlap (occlusion), which likely represents the difficulty and greater individual variation involved in searching more visually complex images. Together, these results demonstrate the effectiveness of a counterintuitive targetless approach to training target detection in X-ray baggage search, based on basic principles of distractor suppression and rejection, with potential for use as a real-world training tool

The Carnegie Supernova Project: Analysis of the First Sample of Low-Redshift Type-Ia Supernovae

We present the analysis of the first set of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project. Well-sampled, high-precision optical (ugriBV) and near-infrared (NIR; YJHKs) light curves obtained in a well-understood photometric system are used to provide light-curve parameters, and ugriBVYJH template light curves. The intrinsic colors at maximum light are calibrated to compute optical--NIR color excesses for the full sample, thus allowing the properties of the reddening law in the host galaxies to be studied. A low value of Rv~1.7, is derived when using the entire sample of SNe. However, when the two highly reddened SNe in the sample are excluded, a value Galactic standard of Rv~3.2 is obtained. The colors of these two events are well matched by a reddening model due to circumstellar dust. The peak luminosities are calibrated using a two-parameter linear fit to the decline rates and the colors, or alternatively, the color excesses. In both cases, dispersions in absolute magnitude of 0.12--0.16 mag are obtained, depending on the filter-color combination. In contrast to the results obtained from color excesses, these fits give Rv~1--2, even when the two highly reddened SNe are excluded. This discrepancy suggests that, beyond the "normal" interstellar reddening produced in the host galaxies, there is an intrinsic dispersion in the colors of SNe Ia which is correlated with luminosity but independent of the decline rate. Finally, a Hubble diagram is produced by combining the results of the fits for each filter. The resulting scatter of 0.12 mag appears to be limited by peculiar velocities as evidenced by the strong correlation between the distance-modulus residuals among the different filters. The implication is that the actual precision of SN Ia distances is 3--4%.Comment: 76 pages, 20 figures, accepted for publication in A

Particle Shadow Tracking - Combining Magnetic Particle Manipulation with In-Situ Optical Detection in a CMOS Microsystem

We present a hybrid CMOS based microsystem where magnetic actuation of microparticles is combined with integrated optical detection via Single Photon Avalanche Diodes (SPADs). The system’s configuration permits the manipulation and detection of single magnetic particles having diameters of 1, 3 and 5 µm. We are able to show a size sensitivity of the particle detection, with a clear distinction between different particle diameters