Generation of Mid-IR Wavelengths

Generation of mid-IR wavelengths Deborah Robinson, Robert Hartsock, and Kelly Gaffney Abstract Research to determine basic molecular properties utilizing pump/probe experiments is an on going effort at SLAC. Here we have been given the task to generate mid-IR laser pulses and commission a mid-IR detector for said experiments and research. The mid-IR pulses will be used to probe the changes in molecular properties induced by exciting the electrons in molecules with visible pump pulses. In order to accomplish this, an optical parametric amplifier (OPA) has been set-up and aligned. The pump beam for the OPA is a 40 femtosecond 800nm beam from a Ti:Sapphire chirped pulse amplified laser system with an output of approximately 1mJ/pulse. In the OPA, one photon of higher energy is frequency mixed or split into two photons of lower energy using nonlinear processes in a nonlinear crystal. Here we have generated 1400nm and 1900nm wavelengths in the near-IR spectrum out of the OPA from the 800nm pump. These signal and idler output wavelengths from the OPA will then be frequency difference mixed in a second nonlinear crystal to yield mid-IR wavelengths to test the mid-IR detector

Beyond Content, Deeper than Delivery: What Critique Feedback Reveals about Communication Expectations in Design Education

In design education, the critique is a communication event in which students present their design and critics provide feedback. Presumably, the feedback gives the students information about their progress on the design. Yet critic feedback also serves a socializing function—providing students information about what it means to communicate well in the design education context. Using a qualitative research methodology, this study explores what critic feedback reflects about expected communication competencies in design studios. Results suggest that communication competence in this setting involves interaction management, demonstration of design evolution, transparent advocacy of intent, explanation of visuals, and the staging of the performance—all of which imply a communicative identity for students that is tethered to the content and delivery of the presentation, but has implications beyond the content and delivery to the broader disciplinary culture. Implications of this study provide insight for faculty and students involved in pedagogical spaces in which feedback plays an important role in the instructional process—suggesting its potential for shaping disciplinary identities, relationships, and social contexts

Ultrafast X-ray Science at the Sub-Picosecond Pulse Source

The ultrafast, high brightness x-ray free electron laser (XFEL) sources of the future have the potential to revolutionize the study of time dependent phenomena in the natural sciences. These linear accelerator (linac) sources will generate femtosecond (fs) x-ray pulses with peak flux comparable to conventional lasers, and far exceeding all other x-ray sources. The Stanford Linear Accelerator Center (SLAC) has pioneered the development of linac science and technology for decades, and since 2000 SLAC and the Stanford Synchrotron Radiation Laboratory (SSRL) have focused on the development of linac based ultrafast electron and x-ray sources. This development effort has led to the creation of a new x-ray source, called the Sub-Picosecond Pulse Source (SPPS), which became operational in 2003 [1]. The SPPS represents the first step toward the world's first hard x-ray free electron laser (XFEL), the Linac Coherent Light Source (LCLS), due to begin operation at SLAC in 2009. The SPPS relies on the same linac-based acceleration and electron bunch compression schemes that will be used at the LCLS to generate ultrashort, ultrahigh peak brightness electron bunches [2]. This involves creating an energy chirp on the electron bunch during acceleration and subsequent compression of the bunch in a series of energy-dispersive magnetic chicanes to create 80 fs electron pulses. The SPPS has provided an excellent opportunity to demonstrate the viability of these electron bunch compression schemes and to pursue goals relevant to the utilization and validation of XFEL light sources

Multi-sensor classification of tennis strokes

In this work, we investigate tennis stroke recognition using a single inertial measuring unit attached to a player’s forearm during a competitive match. This paper evaluates the best approach for stroke detection using either accelerometers, gyroscopes or magnetometers, which are embedded into the inertial measuring unit. This work concludes what is the optimal training data set for stroke classification and proves that classifiers can perform well when tested on players who were not used to train the classifier. This work provides a significant step forward for our overall goal, which is to develop next generation sports coaching tools using both inertial and visual sensors in an instrumented indoor sporting environment

Metabolome-Informed Microbiome Analysis Refines Metadata Classifications and Reveals Unexpected Medication Transfer in Captive Cheetahs.

Even high-quality collection and reporting of study metadata in microbiome studies can lead to various forms of inadvertently missing or mischaracterized information that can alter the interpretation or outcome of the studies, especially with nonmodel organisms. Metabolomic profiling of fecal microbiome samples can provide empirical insight into unanticipated confounding factors that are not possible to obtain even from detailed care records. We illustrate this point using data from cheetahs from the San Diego Zoo Safari Park. The metabolomic characterization indicated that one cheetah had to be moved from the non-antibiotic-exposed group to the antibiotic-exposed group. The detection of the antibiotic in this second cheetah was likely due to grooming interactions with the cheetah that was administered antibiotics. Similarly, because transit time for stool is variable, fecal samples within the first few days of antibiotic prescription do not all contain detected antibiotics, and the microbiome is not yet affected. These insights significantly altered the way the samples were grouped for analysis (antibiotic versus no antibiotic) and the subsequent understanding of the effect of the antibiotics on the cheetah microbiome. Metabolomics also revealed information about numerous other medications and provided unexpected dietary insights that in turn improved our understanding of the molecular patterns on the impact on the community microbial structure. These results suggest that untargeted metabolomic data provide empirical evidence to correct records and aid in the monitoring of the health of nonmodel organisms in captivity, although we also expect that these methods may be appropriate for other social animals, such as cats.IMPORTANCE Metabolome-informed analyses can enhance omics studies by enabling the correct partitioning of samples by identifying hidden confounders inadvertently misrepresented or omitted from carefully curated metadata. We demonstrate here the utility of metabolomics in a study characterizing the microbiome associated with liver disease in cheetahs. Metabolome-informed reinterpretation of metagenome and metabolome profiles factored in an unexpected transfer of antibiotics, preventing misinterpretation of the data. Our work suggests that untargeted metabolomics can be used to verify, augment, and correct sample metadata to support improved grouping of sample data for microbiome analyses, here for nonmodel organisms in captivity. However, the techniques also suggest a path forward for correcting clinical information in microbiome studies more broadly to enable higher-precision analyses

Glucose-lactate metabolic cooperation in cancer: insights from a spatial mathematical model and implications for targeted therapy

A recent study has hypothesised a glucose–lactate metabolic symbiosis between adjacent hypoxic and oxygenated regions of a developing tumour, and proposed a treatment strategy to target this symbiosis. However, in vivo experimental support remains inconclusive. Here we develop a minimal spatial mathematical model of glucose–lactate metabolism to examine, in principle, whether metabolic symbiosis is plausible in human tumours, and to assess the potential impact of inhibiting it. We find that symbiosis is a robust feature of our model system—although on the length scale at which oxygen supply is diffusion-limited, its occurrence requires very high cellular metabolic activity—and that necrosis in the tumour core is reduced in the presence of symbiosis. Upon simulating therapeutic inhibition of lactate uptake, we predict that targeted treatment increases the extent of tissue oxygenation without increasing core necrosis. The oxygenation effect is correlated strongly with the extent of wild-type hypoxia and only weakly with wild-type symbiotic behaviour, and therefore may be promising for radiosensitisation of hypoxic, lactate-consuming tumours even if they do not exhibit a spatially well-defined symbiosis. Finally, we conduct in vitro experiments on the U87 glioblastoma cell line to facilitate preliminary speculation as to where highly malignant tumours might fall in our parameter space, and find that these experiments suggest a weakly symbiotic regime for U87 cells, thus raising the new question of what relationship might exist between symbiosis and tumour malignancy

Likely Impact of the COVID-19 Pandemic on Newborn Hearing Screening and Follow-up Services in the United States in 2020

This perspective aims to highlight aspects of the Early Hearing Detection and Intervention (EHDI) newborn hearing screening and follow-up processes that were impacted by the COVID-19 pandemic and considers factors that likely impacted follow-up after newborn hearing screening among infants born in the United States during 2020. Efforts to minimize the potential impact of missed or delayed identification of hearing loss in infants and young children will also be discussed to help guide future program improvement activities