A Historical Perspective and Review of the Evidence to Support Fruit Bats as the Natural Reservoir for Ebola Viruses

The Ebola viruses cause sporadic outbreaks of Ebola hemorrhagic fever (EHF) where origins have been traced to the continent of Africa and the Philippines. Since the initial discovery of Zaire and Sudan ebolavirus in 1976, the Ebola viruses have been responsible for severe hemorrhagic fever outbreaks in Africa with case fatality rates between 40-90%. The natural reservoir(s) of the Ebola viruses is currently unknown, but there is mounting evidence that fruit bats may play a key role. The goal of the current study is to screen a large variety of bat species from Africa and Asia where Ebola is known to be endemic for the presence of IgG specific antibody to Ebola virus in order to see which bat species may show evidence of past Ebola virus infection. Ebola virus would not be expected to cause lethal disease in its natural reservoir; therefore the presence of IgG antibody would be present. Identifying the species of bats that have been infected will allow researchers to hopefully isolate Ebola virus from bats adding to the evidence that bats are a reservoir species. The knowledge gained may also provide clues to new species of bats yet to be identified as possible natural reservoir(s) as well as expand the known geographical range of known Ebola virus outbreaks. Knowing which species of bats as well as their geographic range may help prevent future Ebola outbreaks by minimizing human-reservoir contact

From Student to Teacher: Renegotiating Professional Identities

This case-study examines how first-year educators renegotiated their teacher identities as they transitioned from pre-service teachers (PSTs) to professionals. Both participants graduated from the same Teacher Education Program (TEP) and conducted their student internship in the same school as their first year of teaching. The results of this study have unique implications on first-year teachers working in the location of their student internships, as they reported isolation, internalized infantilization, and inconsistent identities. The author argues for TEPs to intentionally prepare PSTs for navigating this transition, and challenge preconceived notions of the benefits of student teaching and working in the same K-12 institution

FREQUENCY COMB PHASE-LOCKED CAVITY RING-DOWN SPECTROSCOPY

Cavity ring-down spectroscopy (CRDS) is a widely used tool for trace gas sensing and molecular lineshape studies which involves the use of high-finesse optical cavities to provide long effective pathlengths and high spectral resolution. Here, we present a novel implementation of CRDS where the probe laser is phase locked to a self-referenced octave-spanning optical frequency comb referenced to a Cs clock, and in which the optical cavity is subsequently locked to the stabilized probe laser beam. This approach provides an absolute frequency axis and increased coupling efficiency. It allows for frequency steps of arbitrary size to be made, which can be as small as the order of the linewidth of the stabilized probe laser. The optical cavity follows tunable optical sidebands of the probe laser generated with an electro-optic modulator. This allows for up to 40 GHz of tuning in a single spectral scan, with spectral intervals as small as 200 kHz. The optical cavity is locked to the stabilized probe laser by inducing a slight axial dither (20 kHz modulation amplitude in the optical domain) on a piezo-driven cavity mirror. The resulting transmitted probe beam generates an error signal which can be used to center the piezo offset voltage with a low-bandwidth lock. The absolute frequency uncertainty of the locked probe laser is 1 kHz on a timescale of several hours, which is well in excess of the measurement time. We present a variety of measurements that highlight the power of this technique. Line positions and pressure shifting coefficients can be determined with nearly an order of magnitude smaller uncertainty by comparison to those obtained using conventional FS-CRDS measurements. We apply this technique to several H$_2$O and CO$_2$ transitions in the 1.6 $\mu$m wavelength region and report standard uncertainties in line positions as low as 20 kHz

Spectroscopic line parameters of helium- and hydrogen-broadened 12c16o transitions in the 3–0 band from 6270 cm−1to 6402 cm−1.

We present helium- and hydrogen-broadened linewidths, pressure-induced shifts, and collisional narrowing coefficients for selected lines in the P- and R- branch of the second overtone (3–0) band of CO, spanning from 6270 \wn to 6402 \wn. The contribution of speed dependent effects and partial correlation between velocity-changing and dephasing collisions on the foreign broadened line shapes are also discussed. The data were obtained using the frequency-stabilized cavity ringdown spectroscopy technique. Spectra were collected at room temperature over a pressure range from 13.3 kPa to 100 kPa. The spectrum frequency axis is referenced via an optical frequency comb to a Cs clock, which provides pressure shifting values with uncertainties as low as 100 kHz/atm. The spectra exhibited signal-to-noise ratios as high as 20,000:1, which enables rigorous tests of theoretical line profiles through multi-spectrum least squares data analysis. The partially correlated, quadratic-speed-dependent Nelkin Ghatak profile gives a quality of fit mostly commensurate with the high spectrum signal-to-noise and minimizes structural residuals

HIGH PRECISION 2.0 μm PHOTOACOUSTIC SPECTROMETER FOR DETERMINATION OF THE 13CO2/12CO2 ISOTOPE RATIO

We have developed a portable photoacoustic spectrometer for high precision measurements of the $^{13}$CO$_{2}$/$^{12}$CO$_{2}$ isotope ratio and the absolute molar concentration of each isotope. The spectrometer extends on our previous work at 1.57 $mu$m [1], and now employs two separate intensity modulated distributed feedback lasers and a fiber amplifier, operating in the 2.0 $mu$m wavelength region. Each DFB is selected to probe individual spectrally isolated ro-vibrational transitions for $^{12}$CO$_{2}$ and $^{13}$CO$_{2}$. The spectrometer is actively temperature controlled, mitigating variations in the two spectral line intensities and the temperature dependent system response. _x000d_ _x000d_ For measurements of ambient concentrations of carbon dioxide at nominally natural abundance in dry air, we demonstrate a measurement precision of 140 ppb for $^{12}$CO$_{2}$ with a 1 s averaging time and 10 ppb for $^{13}$CO$_{2}$ with a 60 s averaging time. Precision in $delta$13C of better than 0.1 permil is demonstrated. The analyzer response is calibrated in terms of certified gas mixtures and compared to characterization by cavity ringdown spectroscopy. We also investigate how water vapor affects the photoacoustic signals by promoting collisional relaxation for each isotope. _x000d_ _x000d_ [1] Z.D. Reed, B. Sperling, et al. App. Phys. B. 117, 645-657, 201

MOLECULAR LINE INTENSITIES OF CARBON DIOXIDE IN THE 1.6 μm REGION DETERMINED BY CAVITY RINGDOWN SPECTROSCOPY

Here we present some recent advances in frequency stabilized cavity ring-down spectroscopy (FS-CRDS) measurements of molecular line intensities of carbon dioxide in the (30012)$\leftarrow$ (00001), the (30013)$\leftarrow$(00001), and the (30014)$\leftarrow$(00001) bands near 1.6 $\mu$m. These measurements were performed near 296K using a frequency stabilized cavity ringdown spectrometer [1]. Additional independent measurements were performed on a frequency agile rapid scanning (FARS) CRDS [2]. We have compared the line intensities obtained from Hartmann Tran Profile (HTP) fits of the measured spectra to several spectroscopic databases, including UCL (ie, HITRAN2016) [3]. The overall agreement between these results and the ab initio calculations of Zak et al is excellent [3], although some individual transitions show deviations of up to 1\%. The intensities for the (30012)$\leftarrow$(00001) show average agreement at the 0.1\% level. Preliminary measurements on the (30013)$\leftarrow$(00001), and the (30014)$\leftarrow$(00001) bands in this region also show good agreement with the ab initio of Zak et al for the (30013)$\leftarrow$(00001), but considerably poorer agreement for the (30014)$\leftarrow$(00001) band. No significant J-dependence is observed for any of the three bands. This work demonstrates significant improvement in experimental determination of important CO$_{2}$ line intensities in the 1.6 $\mu$m region. It also demonstrates that it may be feasible for ab initio theory to provide sufficiently accurate results for global determinations of line intensities in the near future. [1] H. Lin, Z. D. Reed, V. T. Sironneau, and J. T. Hodges, J. Quant. Spectrosc. Radiat. Transfer 161, 11-20 (2015). [2] G. W. Truong, K. O. Douglass, S. E. Maxwell, R. D. van Zee, D. F. Plusquellic, J. T. Hodges, and D. A. Long, Nat. Photonics 7, 532-534 (2013). [3] E. J. Zak, J. Tennyson, O. L. Polyansky, L. Lodi, N. F. Zobov, S. A. Tashkun, and V. I. Perevalov, J. Quant. Spectrosc. Radiat. Transfer 189, 267-280 (2017)

FREQUENCY-AGILE DIFFERENTIAL CAVITY RING-DOWN SPECTROSCOPY

The ultimate precision of highly sensitive cavity-enhanced spectroscopic measurements is often limited by interferences (etalons) caused by weak coupled-cavity effects. Differential measurements of ring-down decay constants have previously been demonstrated to largely cancel these effects, but the measurement acquisition rates were relatively low [1,2]. We have previously demonstrated the use of frequency agile rapid scanning cavity ring-down spectroscopy (FARS-CRDS) for acquisition of absorption spectra [3]. Here, the method of rapidly scanned, frequency-agile differential cavity ring-down spectroscopy (FADS-CRDS) is presented for reducing the effect of these interferences and other shot-to-shot statistical variations in measured decay times. To this end, an electro-optic phase modulator (EOM) with a bandwidth of 20 GHz is driven by a microwave source, generating pairs of sidebands on the probe laser. The optical resonator acts as a highly selective optical filter to all laser frequencies except for one tunable sideband. This sideband may be stepped arbitrarily from mode-to-mode of the ring-down cavity, at a rate limited only by the cavity buildup/decay time. The ability to probe any cavity mode across the EOM bandwidth enables a variety of methods for generating differential spectra. The differential mode spacing may be changed, and the effect of this method on suppressing the various coupled-cavity interactions present in the system is discussed. Alternatively, each mode may also be differentially referenced to a single point, providing immunity to temporal variations in the base losses of the cavity while allowing for conventional spectral fitting approaches. Differential measurements of absorption are acquired at 3.3 kHz and a minimum detectable absorption coefficient of 5 x10$^{-12}$ cm$^{-1}$ in 1 s averaging time is achieved. \ \ \ 1. J. Courtois, K. Bielska, and J.T Hodges J. Opt. Soc. Am. B, 30, 1486-1495, 2013 \ 2. H.F. Huang and K.K. Lehmann App. Optics 49, 1378-1387, 2010 \ 3. G.-W. Truong, K.O. Douglass, S.E. Maxwell, R.D. van Zee, D.F. Plusquellic, J.T. Hodges, and D.A. Long Nature Photonics, 7, 532-534, 201

LINE SHAPES AND INTENSITIES OF CARBON MONOXIDE TRANSITIONS IN THE (3→0) AND (4→1) BANDS

We have measured several carbon monoxide transitions in the (3$rightarrow$0) and (4$rightarrow$1) band using frequency stabilized cavity ringdown spectroscopy (FS-CRDS). The measured transitions are compared to the line strength values in HITRAN 2012 [1], those determined by Wojtewitz et al [2], and to theoretical calculations. The cavity length is actively locked to an iodine stabilized HeNe laser, providing long term frequency stability of 10 kHz and is linked to a self-referenced, octave-spanning frequency comb. The temperature of the optical cavity is actively regulated at the mK level, and the pressure measurements are SI-traceable. The sample is a NIST calibrated reference mixture of 11.98575(95)% CO in N$_{2}$. _x000d_ The absorption spectra are modeled using the Hartmann-Tran profile (HTP). The SNR in these spectra may exceed 10,000:1, which necessitates including the effects of speed dependence, collisional narrowing, and correlation between velocity-changing and dephasing collisions. _x000d_ _x000d_ The relative uncertainties of the line strengths calculated in this study are better than 0.1%. There are systematic differences on the 1% level for $^{12}$CO against both HITRAN [1] and the previous work by Wojtewitz et al [2]. The measurement uncertainties are nearly an order of magnitude lower than previous results. Additionally, the relative uncertainties in the integrated areas of selected $^{12}$CO and $^{13}$CO transitions are less than 0.006% and 0.02%, respectively, providing an excellent test case for determination of isotope ratios by direct use of theoretical line intensity calculations. _x000d_ _x000d_ $newline$_x000d_ [1] Wojtewicz, S., et al., J Quant Spect and Rad Trans,2013. 130: p.191-200. $newline$_x000d_ [2]Rothman, L.S., et al., Journal of Quant Spect and Rad Trans, 2013. 130: p. 4-50._x000d

Immunological and physiochemical characterization of fish myosins

Increased sales of surimi seafood, with the majority as crabstick in the United States indicates that surimi based products are becoming more popular. With growing popularity, there is increased competition for market share. Under these circumstances, some companies may be willing to sacrifice product quality in order to facilitate manufacture and reduce price as a means of gaining market share. During the last 10 years, poor quality imports, which exceeded nearly 2 million pounds a year, have negatively impacted the domestic market. The most important factor in surimi production is the textural properties imparted by the fish protein. Consequently, crabstick quality is directly related to the amount of fish protein from raw surimi that is used. A high quality crabstick product typically contains 40% or higher fish protein. The protein content and quality of raw surimi are varied by fish species and surimi grade. As a way to increase profits, lower quality products can be sold while claiming they are made primarily of high quality fish protein surimi. Indirect enzyme-linked immunosorbent assays (ELISA) technique was used to identify and quantify the use of dried egg white (DEW) and whey protein concentrate (WPC) in crabsticks. The use of SDS-PAGE for the quantification of protein additives has had limited success due to the high shear and high temperature processes of surimi crabstick. Monoclonal (anti-heat denatured ovalbumin) and polyclonal (anti-β-lactoglobulin) antibodies were used. Antibodies showed no significant cross-reactivity with non-target crabstick proteins. An optimized extraction solution of 10% SDS and 2.5% βME yielded high extractability with improved consistency. Quantification of DEW and WPC was achieved using the optimized extraction solution and indirect ELISA. Estimated DEW values were within 7% of actual values, WPC samples were within 17%. Inter-assay coefficients of variance for DEW ranged from 0.9% to 3.1% and those of the WPC were 1.0% to 8.0%. A competitive enzyme-linked immunosorbent assay (ELISA) was developed for quantification of Alaska pollock (AP) surimi in crabsticks. Identification of fish species is complicated by processing, cooking, and additional ingredients. ELISA is a powerful tool for identification and quantification of fish species. Polyclonal antibodies were raised in rabbits against a 15-amino-acid peptide (Ala-Pro-Lys-Lys-Asp-Val-Lys-Ala-Pro- Ala-Ala-Ala-Ala-Lys-Lys) determined from the myosin light chain 1 (MLC 1) of AP. Immunoblotting showed the anti-pep-AP antibody had no significant cross-reactivity with protein additives. However, cross-reactivity of the MLC 1 from Pacific whiting, and threadfin bream surimi was observed. MLC 1 was purified from AP surimi and used as the coating protein in the competitive ELISA. MLC 1 was serially diluted and had a R² of 0.9845 following a logarithmic curve. All estimations of AP surimi were within 9% of the actual value. Inter-assay coefficients of variance ranged from 4.2 to 4.9%. Antibodies were produced by injection of a synthesized 15-amino acid peptide or by whole myosin light chain 1 isolated from Alaska pollock (AP). A direct sandwich ELISA was tested using extracts prepared from AP, Pacific whiting (PW), true cod (TC), tilapia (T), and catfish (C). Fish extracts were studied using SDS-PAGE and Western blotting. A standard curve was created for each fish and used to estimate 3 different verification samples. All estimations were within 10, 37.5, 30, 43, and 34% of the actual value for AP, PW, TC, T, and C, respectively. When one or more fish species was mixed together with AP the estimation of the Alaska pollock content became much less accurate. This study confirms a direct sandwich ELISA accurately detects the quantity of AP. Testing found the sandwich ELISA developed exhibited cross-reactivity with other protein sources such as beef, chicken, pork, shrimp, and clam. Purified Chinook salmon myosin was studied using SDS-PAGE and densitometric analysis to determine its purity, which was 94%. Myosin subjected to linear heating began to form aggregates at > 24 °C as measured by turbidity at 320 nm. Conformational changes, as measured by surface hydrophobicity (S[subscript o]), began at 18.5 °C and continued to increase up to 75 °C after which it decreased slightly. Total sulfhydryl content (TSH) showed similar trends from 18.5 to 50 °C after which point the TSH began to drop. Surface reactive sulfhydryl groups (SRSH) gradually increased as the temperature increased from 18.5 to 50 °C and then followed a similar trend as the TSH decreased from 55 to 80 °C. Differential scanning calorimetry showed four peaks, three endothermic (27.9, 36.0, 45.5 °C) and one exothermic (49.0 °C). Dynamic rheological measurements provided information concerning the gelation point of salmon myosin which was 31.1 °C as samples were heated at 2 °C/min. Purified tilapia myosin was digested with α-chymotrypsin and purified to obtain heavy meromyosin (HMM) and light meromyosin (LMM). Tilapia myosin, HMM, and LMM were studied using SDS-PAGE. Myosin, HMM, and LMM were linearly heated from 10 to 90 °C and showed protein denaturation/aggregation during heating as measured by turbidity at 320 nm. Conformational changes as measured by surface hydrophobicity (S[subscript o]) showed a marked increase for myosin and HMM between 30 and 40 °C and reached a stable plateau at 70 °C. LMM, in an extremely small magnitude, also showed a continuous increase to 70 °C. Total sulfhydryl content (TSH) showed that the –SH residue content of HMM was nearly double that of LMM. Surface reactive sulfhydryl groups (SRSH) for myosin and HMM were relatively unchanged from 10 to 30 °C but increased significantly from 30 to 50 °C. SRSH content of LMM was lower than that of the TSH content of LMM but both showed a slightly decreasing trend as the sample was heated. Differential scanning calorimetry showed 3 (17.5, 41.9, and 49.9 °C), 2 (43.0 and 67.1 °C), and 3 (40.4, 51.7, and 69.0 °C) major peaks for myosin, HMM, and LMM, respectively. Dynamic rheological measurements demonstrated crossover points, which are generally recognized as gelation point, 40.3 °C for myosin and 27.0 °C for HMM. Obtaining antibodies that would bind the target protein in the highly processed crabstick proved to be a key for the success for assay development. The anti-pep-AP antibody proved to be very accurate in the qualification and quantification of Alaska pollock surimi used in crabsticks. Using the appropriate ELISA format, competitive vs. indirect, proved to be pivotal in obtaining accuracy and repeatability of the assay. Using a direct sandwich ELISA for the qualification and quantification Alaska raw fish fillets provided good estimation of Alaska pollock used in the verification sample. However, the Alaska pollock MLC 1 antibodies exhibited high levels of cross reactivity with other fish species. It has been shown that salmon myosin can be affected by heating. As myosin was heated in solution myosin aggregates began to form as evidenced by the increased turbidity. Myosin denaturation and gel formation was also supported by the thermal transition points determined from differential scanning calorimetry and dynamic rheology. The exposure of buried hydrophobic and sulfhydryl groups of myosin was increased as the myosin was linearly heated. The study of tilapia myosin, HMM, and LMM carried out from chymotryptic digestion of myosin allowed for important insights into the thermo stability and gelation properties of tilapia

Placental Mesenchymal Stem Cell-Derived Extracellular Vesicles Promote Myelin Regeneration in an Animal Model of Multiple Sclerosis.

Mesenchymal stem/stromal cells (MSCs) display potent immunomodulatory and regenerative capabilities through the secretion of bioactive factors, such as proteins, cytokines, chemokines as well as the release of extracellular vesicles (EVs). These functional properties of MSCs make them ideal candidates for the treatment of degenerative and inflammatory diseases, including multiple sclerosis (MS). MS is a heterogenous disease that is typically characterized by inflammation, demyelination, gliosis and axonal loss. In the current study, an induced experimental autoimmune encephalomyelitis (EAE) murine model of MS was utilized. At peak disease onset, animals were treated with saline, placenta-derived MSCs (PMSCs), as well as low and high doses of PMSC-EVs. Animals treated with PMSCs and high-dose PMSC-EVs displayed improved motor function outcomes as compared to animals treated with saline. Symptom improvement by PMSCs and PMSC-EVs led to reduced DNA damage in oligodendroglia populations and increased myelination within the spinal cord of treated mice. In vitro data demonstrate that PMSC-EVs promote myelin regeneration by inducing endogenous oligodendrocyte precursor cells to differentiate into mature myelinating oligodendrocytes. These findings support that PMSCs' mechanism of action is mediated by the secretion of EVs. Therefore, PMSC-derived EVs are a feasible alternative to cellular based therapies for MS, as demonstrated in an animal model of the disease