Influences of Chronic Stress on Irritable Bowel Syndrome, Anxiety, Depression, and the Microbiome

IBS effects approximately 5% of the world’s population with symptoms ranging from unexplainable constipation to daily abdominal pain. Though treatment options are available and have been proven beneficial for certain individuals, discovering the root cause of IBS has been difficult to accomplish due to the variety of symptoms that differ from case to case. This study aims to increase understanding of the influence that chronic stress has on irritable bowel syndrome, anxiety, depression, and the microbiome in the college-age population since this group is likely to experience daily stressors, anxiety- and depressive-like thoughts, as well as IBS symptoms. Current research suggests that anxiety and depression, the microbiome, and the gut- brain axis are in some way associated with symptoms of IBS. This research used a survey design with quantitative analysis of data and was distributed to a random sample of undergraduate students at Grand Valley State University. The survey contained questions about the participants’ bowel habits, anxiety levels, depression levels, and perceived stress levels. Frequencies, Prevalence Ratios, Ordinal Regression, Crosstabulations, and Pearson’s Chi-Square or Fisher’s Exact test were used to understand the prevalence of IBS diagnosis and IBS symptoms compared to stress, anxiety, and depression scores. The data indicate that among college students without a medical diagnosis of IBS, higher levels of IBS symptoms are associated with severe levels of stress, moderate to severe levels of anxiety, and moderate to severe levels of depression. By encouraging the idea that these symptoms are interrelated, it can increase awareness for medical professionals to screen patients for IBS if they score high on mood disorder or stress surveys. Furthermore, treatment options can be updated in terms of medical nutrition therapy as well as related to mental health in order to arm individuals with the necessary tools that they need to treat this syndrome and overcome painful and uncomfortable symptoms

Study of a harmonic mode lock stability under external continuous-wave injection

In this paper, we investigate experimentally the effect of an injected continuous external optical laser in a stable passive harmonic mode-locked fiber laser operating in the anomalous dispersion regime. Under specific conditions, the continuous-wave significantly increases the stability of the harmonic mode-locked regime. This occurs for a discrete set of wavelengths and below a critical injected power

Spectral dynamics of square pulses in passively mode-locked fiber lasers

We investigate experimentally and numerically the spectral dynamics of square pulses generated in passively mode-locked fiber lasers under the dissipative soliton resonance. The features of the transition from the single-peak spectral profile to the doublet spectrum with increasing pump power are studied. The used master equation takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. Experimental data are obtained for an Er:Yb-doped fiber ring laser. The theoretical and experimental results are in good agreement with each other

Harmonic dissipative soliton resonance square pulses in an anomalous dispersion passively mode-locked fiber ring laser

We demonstrate the generation of dissipative soliton resonance square pulses from a co-doped Er:Yb double-clad fiber ring laser operating in an all anomalous dispersion regime. The obtained pulses have a repetition rate of 672 kHz and a pulse energy of 409 nJ. By carefully adjusting the polarization controllers while increasing the pump power, the square pulse can split into a series of identical equally spaced smaller square pulses up to the 13th harmonic of the fundamental repetition frequency. The average output energy of the square pulses follows a scaling law versus the harmonic orde

Strong HI Lyman-α\alpha variations from the 11 Gyr-old host star Kepler-444: a planetary origin ?

Kepler-444 provides a unique opportunity to probe the atmospheric composition and evolution of a compact system of exoplanets smaller than the Earth. Five planets transit this bright K star at close orbital distances, but they are too small for their putative lower atmosphere to be probed at optical/infrared wavelengths. We used the Space Telescope Imaging Spectrograph instrument onboard the Hubble Space Telescope to search for the signature of the planet's upper atmospheres at six independent epochs in the Ly-$\alpha$ line. We detect significant flux variations during the transits of both Kepler-444e and f (~20%), and also at a time when none of the known planets was transiting (~40%). Variability in the transition region and corona of the host star might be the source of these variations. Yet, their amplitude over short time scales (~2-3 hours) is surprisingly strong for this old (11.2+-1.0Gyr) and apparently quiet main-sequence star. Alternatively, we show that the in-transits variations could be explained by absorption from neutral hydrogen exospheres trailing the two outer planets (Kepler-444e and f). They would have to contain substantial amounts of water to replenish such hydrogen exospheres, which would reveal them as the first confirmed ocean-planets. The out-of-transit variations, however, would require the presence of a yet-undetected Kepler-444g at larger orbital distance, casting doubt on the planetary origin scenario. Using HARPS-N observations in the sodium doublet, we derived the properties of two Interstellar Medium clouds along the line-of-sight toward Kepler-444. This allowed us to reconstruct the stellar Ly-$\alpha$ line profile and to estimate the XUV irradiation from the star, which would still allow for a moderate mass loss from the outer planets after 11.2Gyr. Follow-up of the system at XUV wavelengths will be required to assess this tantalizing possibility.Comment: Accepted for publication in A&A Name of the system added to the title in most recent versio

Investigating Cepheid ℓ\ell Carinae's Cycle-to-cycle Variations via Contemporaneous Velocimetry and Interferometry

Baade-Wesselink-type (BW) techniques enable geometric distance measurements of Cepheid variable stars in the Galaxy and the Magellanic clouds. The leading uncertainties involved concern projection factors required to translate observed radial velocities (RVs) to pulsational velocities and recently discovered modulated variability. We carried out an unprecedented observational campaign involving long-baseline interferometry (VLTI/PIONIER) and spectroscopy (Euler/Coralie) to search for modulated variability in the long-period (P $\sim$ 35.5 d) Cepheid Carinae. We determine highly precise angular diameters from squared visibilities and investigate possible differences between two consecutive maximal diameters, $\Delta_{\rm{max}} \Theta$. We characterize the modulated variability along the line-of-sight using 360 high-precision RVs. Here we report tentative evidence for modulated angular variability and confirm cycle-to-cycle differences of $\ell$ Carinae's RV variability. Two successive maxima yield $\Delta_{\rm{max}} \Theta$ = 13.1 $\pm$ 0.7 (stat.) {\mu}as for uniform disk models and 22.5 $\pm$ 1.4 (stat.) {\mu}as (4% of the total angular variation) for limb-darkened models. By comparing new RVs with 2014 RVs we show modulation to vary in strength. Barring confirmation, our results suggest the optical continuum (traced by interferometry) to be differently affected by modulation than gas motions (traced by spectroscopy). This implies a previously unknown time-dependence of projection factors, which can vary by 5% between consecutive cycles of expansion and contraction. Additional interferometric data are required to confirm modulated angular diameter variations. By understanding the origin of modulated variability and monitoring its long-term behavior, we aim to improve the accuracy of BW distances and further the understanding of stellar pulsations.Comment: Accepted for publication in MNRAS. 19 pages, 13 figures, 10 table

Multisoliton hybrid generation of fiber lasers with anomalous dispersion

We have performed a numerical simulation study of a hybrid regime of anomalous-dispersion-fiber lasers inwhich passive mode locking occurs simultaneously with the regime of regular undamped spikes induced by anintracavity saturable absorber. Stabilization and reproducibility of the laser radiation is provided by a fiber opticaldelay line due to which each subsequent spike is formed from the seed radiation of the previous one. The transientevolution and steady-state generation are analyzed. It is found that the number of ultrashort pulses in the steady-state generation depends on the initial conditions of the transient process. In the investigated generation, thespatial-temporal concentration of radiation energy is due to both passive mode locking andQ-switch operation.The hybrid regime is of interest for obtaining reproducible high-energy light pulse

Theory of passively-mode-locked fiber lasers with phase-modulated square pulses

We present results of the analysis of square pulses generated in passively-mode-locked lasers under dissipative-soliton-resonance conditions. The master equation used in this work takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. The phase modulation effects are defined as a perturbation to the solution of this equation that has the form of a square pulse without phase modulation. An analytical dependence of the change in the carrier frequency of the radiation along the pulse is found. Conditions for the occurrence of the singlet and doublet spectra of the square pulse are determined. The mechanisms responsible for the occurrence of this regime are analyzed. The obtained analytical dependencies are in good agreement with the results of numerical simulation