The effect of rapid relative humidity changes on fast filter-based aerosol-particle light-absorption measurements: Uncertainties and correction schemes

Measuring vertical profiles of the particle light-absorption coefficient by using absorption photometers may face the challenge of fast changes in relative humidity (RH). These absorption photometers determine the particle light-absorption coefficient due to a change in light attenuation through a particle-loaded filter. The filter material, however, takes up or releases water with changing relative humidity (RH in %), thus influencing the light attenuation. A sophisticated set of laboratory experiments was therefore conducted to investigate the effect of fast RH changes (dRH/dt) on the particle light-absorption coefficient (σabs in Mm-1) derived with two absorption photometers. The RH dependence was examined based on different filter types and filter loadings with respect to loading material and areal loading density. The Single Channel Tricolor Absorption Photometer (STAP) relies on quartz-fiber filter, and the microAeth® MA200 is based on a polytetrafluoroethylene (PTFE) filter band. Furthermore, three cases were investigated: clean filters, filters loaded with black carbon (BC), and filters loaded with ammonium sulfate. The filter areal loading densities (ρ∗) ranged from 3.1 to 99.6 mg m-2 in the case of the STAP and ammonium sulfate and 1.2 to 37.6 mg m-2 in the case the MA200. Investigating BC-loaded cases, M8 scroll mrow miBCm 15pt was in the range of 2.9 to 43.0 and 1.1 to 16.3 mg m-2 for the STAP and MA200, respectively. Both instruments revealed opposing responses to relative humidity changes ("RH) with different magnitudes. The STAP shows a linear dependence on relative humidity changes. The MA200 is characterized by a distinct exponential recovery after its filter was exposed to relative humidity changes. At a wavelength of 624 nm and for the default 60 s running average output, the STAP reveals an absolute change in σabs per absolute change of RH ("σabsĝ•"RH) of 0.14 Mm-1 %-1 in the clean case, 0.29 Mm-1 %-1 in the case of BC-loaded filters, and 0.21 Mm-1 %-1 in the case filters loaded with ammonium sulfate. The 60 s running average of the particle light-absorption coefficient at 625 nm measured with the MA200 revealed a response of around -0.4 Mm-1 %-1 for all three cases. Whereas the response of the STAP varies over the different loading materials, in contrast, the MA200 was quite stable. The response was, for the STAP, in the range of 0.17 to 0.24 Mm-1 %-1 and, in the case of ammonium sulfate loading and in the BC-loaded case, 0.17 to 0.62 Mm-1 %-1. In the ammonium sulfate case, the minimum response shown by the MA200 was -0.42 with a maximum of -0.36 Mm-1 %-1 and a minimum of -0.42 and maximum -0.37 Mm-1 %-1 in the case of BC. A linear correction function for the STAP was developed here. It is provided by correlating 1 Hz resolved recalculated particle light-absorption coefficients and RH change rates. The linear response is estimated at 10.08 Mm-1 s-1 %-1. A correction approach for the MA200 is also provided; however, the behavior of the MA200 is more complex. Further research and multi-instrument measurements have to be conducted to fully understand the underlying processes, since the correction approach resulted in different correction parameters across various experiments. However, the exponential recovery after the filter of the MA200 experienced a RH change could be reproduced. However, the given correction approach has to be estimated with other RH sensors as well, since each sensor has a different response time. And, for the given correction approaches, the uncertainties could not be estimated, which was mainly due to the response time of the RH sensor. Therefore, we do not recommend using the given approaches. But they point in the right direction, and despite the imperfections, they are useful for at least estimating the measurement uncertainties due to relative humidity changes. Due to our findings, we recommend using an aerosol dryer upstream of absorption photometers to reduce the RH effect significantly. Furthermore, when absorption photometers are used in vertical measurements, the ascending or descending speed through layers of large relative humidity gradients has to be low to minimize the observed RH effect. But this is simply not possible in some scenarios, especially in unmixed layers or clouds. Additionally, recording the RH of the sample stream allows correcting for the bias during post-processing of the data. This data correction leads to reasonable results, according to the given example in this study. © Author(s) 2019

Climatic fluctuations inferred for the Middle and Late Pleniglacial (MIS 2) based on high-resolution (∼ca. 20 y) preliminary environmental magnetic investigation of the loess section of the Madaras brickyard (Hungary)

Abstract The Madaras brickyard section found at the northernmost fringe of the Backa loess plateau is one of the thickest and best-developed last glacial loess sequences of Central Europe. In the present work high-resolution magnetic susceptibility measurements (at 2 cm) were implemented on samples from the 10 m-section corresponding to a period between 29 and 11 KY cal b2K. One aim was to compare the findings with the ice core records of northern Greenland in order to establish a high-resolution paleoclimatic record for the last climatic cycle and with findings documented in other biotic and abiotic proxies so far. Our results revealed a strong variability of loess/paleosol formation during MIS 2. Millennial time-scale climatic events that characterize the North Atlantic during the last climatic cycle have been identified. From 29 ka up to the start of the LGM, the recorded MS values show a weak, negative correlation with the temperature proxy, and a weak positive correlation with the dust concentration of Greenland. A strong correlation was observed with the local paleotemperatures. Local climatic factors must have had a more prominent effect here on loess/paleosol development than the climate shifts over Greenland. During the LGM the same pattern is seen with a stronger correlation with the dust concentrations and a weaker correlation with the local temperature. Local climatic factors, plus dust accumulation, must have had a prominent influence on loess/paleosol development here. From the terminal part of the LGM a strong positive correlation of the MS values with the temperature proxy for Greenland accompanied by a strong negative correlation with the dust concentration values is observed. Correlation with local paleotemperatures is positive and moderate, strong. Here climate shifts over Greenland, as well as local endowments equally had an important role on the development of the MS signal

The Compliance Model of Employment Standards Enforcement: An Evidence-based Assessment of its Efficacy in Instances of Wage Theft

This article critically assesses the compliance model of employment standards (ES) enforcement through a study of monetary employment standards violations in Ontario, Canada. The findings suggest that, in contexts where changes to the organization of work deepen insecurity for employees, models of enforcement that emphasize compliance over deterrence are unlikely to effectively prevent or remedy ES violations

Patient-Specific Prosthetic Fingers by Remote Collaboration - A Case Study

The concealment of amputation through prosthesis usage can shield an amputee from social stigma and help improve the emotional healing process especially at the early stages of hand or finger loss. However, the traditional techniques in prosthesis fabrication defy this as the patients need numerous visits to the clinics for measurements, fitting and follow-ups. This paper presents a method for constructing a prosthetic finger through online collaboration with the designer. The main input from the amputee comes from the Computer Tomography (CT) data in the region of the affected and the non-affected fingers. These data are sent over the internet and the prosthesis is constructed using visualization, computer-aided design and manufacturing tools. The finished product is then shipped to the patient. A case study with a single patient having an amputated ring finger at the proximal interphalangeal joint shows that the proposed method has a potential to address the patient's psychosocial concerns and minimize the exposure of the finger loss to the public.Comment: Open Access articl

An in-plane photoelectric effect in two-dimensional electron systems for terahertz detection

Many mid- and far-infrared semiconductor photodetectors rely on a photonic response, when the photon energy is large enough to excite and extract electrons due to optical transitions. Toward the terahertz range with photon energies of a few milli–electron volts, classical mechanisms are used instead. This is the case in two-dimensional electron systems, where terahertz detection is dominated by plasmonic mixing and by scattering-based thermal phenomena. Here, we report on the observation of a quantum, collision-free phenomenon that yields a giant photoresponse at terahertz frequencies (1.9 THz), more than 10-fold as large as expected from plasmonic mixing. We artificially create an electrically tunable potential step within a degenerate two-dimensional electron gas. When exposed to terahertz radiation, electrons absorb photons and generate a large photocurrent under zero source-drain bias. The observed phenomenon, which we call the “in-plane photoelectric effect,” provides an opportunity for efficient direct detection across the entire terahertz range.George and Lilian Schiff Studentship, Schiff Foundation, University of Cambridge Honorary Vice-Chancellor’s Award, Cambridge Trust, University of Cambridg

Depression and risk factors for depression among mothers of sick infants in Kumasi, Ghana

ObjectiveTo describe the prevalence of and risk factors for depression in a high‐risk population of mothers of ill newborns in Ghana.MethodsSemi‐structured interviews were conducted with women who had a hospitalized newborn at a tertiary teaching hospital in Kumasi, Ghana. Surveys included information on maternal demographics, pregnancy and delivery, interpersonal violence, and social support. Postpartum depression was measured with the Patient Health Questionnaire (PHQ)‐9. Bivariable analysis was conducted using analysis of variance, χ2, and Fisher exact tests; multivariable analysis was performed using multinomial logistic regression.ResultsIn total, 153 women completed the survey. Fifty (32.7%) had PHQ‐9 scores of 5–9, indicating mild depression; 42 (27.4%) had PHQ‐9 scores of 10–14, indicating moderate depression; and 15 (9.8%) had scores of 15 or higher, indicative of moderate/severe depression. History of interpersonal violence with current partner predicted depression.ConclusionMothers of sick infants in Ghana are at high risk for symptoms of clinical depression. This is of critical importance because maternal depression affects infant health outcomes and may be particularly important for mothers of sick infants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135602/1/ijgo228.pd

Characterisation of the pathogenic effects of the in vivo expression of an ALS-linked mutation in D-amino acid oxidase: Phenotype and loss of spinal cord motor neurons

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset neuromuscular disorder characterised by selective loss of motor neurons leading to fatal paralysis. Current therapeutic approaches are limited in their effectiveness. Substantial advances in understanding ALS disease mechanisms has come from the identification of pathogenic mutations in dominantly inherited familial ALS (FALS). We previously reported a coding mutation in D-amino acid oxidase (DAOR199W) associated with FALS. DAO metabolises D-serine, an essential co-agonist at the N-Methyl-D-aspartic acid glutamate receptor subtype (NMDAR). Using primary motor neuron cultures or motor neuron cell lines we demonstrated that expression of DAOR199W, promoted the formation of ubiquitinated protein aggregates, activated autophagy and increased apoptosis. The aim of this study was to characterise the effects of DAOR199W in vivo, using transgenic mice overexpressing DAOR199W. Marked abnormal motor features, e.g. kyphosis, were evident in mice expressing DAOR199W, which were associated with a significant loss (19%) of lumbar spinal cord motor neurons, analysed at 14 months. When separated by gender, this effect was greater in females (26%; p< 0.0132). In addition, we crossed the DAOR199W transgenic mouse line with the SOD1G93A mouse model of ALS to determine whether the effects of SOD1G93A were potentiated in the double transgenic line (DAOR199W/SOD1G93A). Although overall survival was not affected, onset of neurological signs was significantly earlier in female double transgenic animals than their female SOD1G93A littermates (125 days vs 131 days, P = 0.0239). In summary, some significant in vivo effects of DAOR199W on motor neuron function (i.e. kyphosis and loss of motor neurons) were detected which were most marked in females and could contribute to the earlier onset of neurological signs in double transgenic females compared to SOD1G93A littermates, highlighting the importance of recognizing gender effects present in animal models of ALS

Tools and methods for providing assurance of clonality for legacy cell lines

Over the last several years demonstration of cell line clonality has been a topic of many industry and regulatory presentations and papers. Guidance has been provided by the regulatory authorities, especially the FDA, on a path forward for providing evidence of clonality with high probability. It has been recommended that two-rounds of limiting dilution cloning (LDC) at sufficiently low seeding densities (≤0.5 cells/well) provides sufficient evidence that a cell line is clonal. Furthermore, one-round of LDC may also suffice if supplemental data from a characterized FACS or plate-imaging workflow are also included in the package. Cell lines generated by methods that do not demonstrate high probability of clonal derivation, including legacy cell lines, may require additional studies to provide assurance and/or process control strategies to satisfy regulatory expectations. Within the Biologics function of the IQ Consortium the “Clonality” Working Group is focusing on methods and tools which could be utilized to provide a high assurance of clonality for legacy cell lines. The presentation will outline a three tier approach to address legacy cell line clonality assurance: standard practices already used in industry to support limit of in vitro cell age studies, enhanced control strategies to ensure process consistency, and emerging technologies that could be used to further support cell line clonality

Past, present, and future of the Living Planet Index

As we enter the next phase of international policy commitments to halt biodiversity loss (e.g., Kunming-Montreal Global Biodiversity Framework), biodiversity indicators will play an important role in forming the robust basis upon which targeted, and time sensitive conservation actions are developed. Population trend indicators are one of the most powerful tools in biodiversity monitoring due to their responsiveness to changes over short timescales and their ability to aggregate species trends from global down to sub-national or even local scale. We consider how the project behind one of the foremost population level indicators - the Living Planet Index - has evolved over the last 25 years, its value to the field of biodiversity monitoring, and how its components have portrayed a compelling account of the changing status of global biodiversity through its application at policy, research and practice levels. We explore ways the project can develop to enhance our understanding of the state of biodiversity and share lessons learned to inform indicator development and mobilise action