Patterns of Oral Microbiota Diversity in Adults and Children: A Crowdsourced Population Study.

Oral microbiome dysbiosis has been associated with various local and systemic human diseases such as dental caries, periodontal disease, obesity, and cardiovascular disease. Bacterial composition may be affected by age, oral health, diet, and geography, although information about the natural variation found in the general public is still lacking. In this study, citizen-scientists used a crowdsourcing model to obtain oral bacterial composition data from guests at the Denver Museum of Nature & Science to determine if previously suspected oral microbiome associations with an individual's demographics, lifestyle, and/or genetics are robust and generalizable enough to be detected within a general population. Consistent with past research, we found bacterial composition to be more diverse in youth microbiomes when compared to adults. Adult oral microbiomes were predominantly impacted by oral health habits, while youth microbiomes were impacted by biological sex and weight status. The oral pathogen Treponema was detected more commonly in adults without recent dentist visits and in obese youth. Additionally, oral microbiomes from participants of the same family were more similar to each other than to oral microbiomes from non-related individuals. These results suggest that previously reported oral microbiome associations are observable in a human population containing the natural variation commonly found in the general public. Furthermore, these results support the use of crowdsourced data as a valid methodology to obtain community-based microbiome data

Determination of two-photon exchange amplitudes from elastic electron-proton scattering data

Using the available cross section and polarization data for elastic electron-proton scattering, we provide an extraction of the two-photon exchange amplitudes at a common value of four-momentum transfer, around Q^2 = 2.5 GeV^2. This analysis also predicts the e^+ p / e^- p elastic scattering cross section ratio, which will be measured by forthcoming experiments.Comment: 4 pages, 5 figures, updated error analysi

Deeply Virtual Compton Scattering off the Neutron

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e⃗,e′γ)X cross section measured at Q2=1.9  GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to Eq, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced

Mjerenje omjera električnog i magnetskog faktora oblika protona odbojnom polarizacijom

The longitudinal and transverse polarizations of the outgoing proton were measured for the reaction 1H(→ e , e′ → p) at four-momentum transfer squared of 0.5 to 3.5 GeV2 . The ratio of the electric to magnetic form factors of the proton is proportional to the ratio of the transverse to longitudinal polarizations.Mjerila se uzdužna i poprečna polarizacija izlaznih protona u reakciji 1H(→ e , e′ → p) za kvadrate prijenosa četiri-impulsa od 0.5 do 3.5 GeV2 . Omjer električnog i magnetskog faktora oblika protona je razmjeran omjeru poprečne i uzdužne polarizacije

Mjerenje odbojne polarizacije u reakciji 16^O (→ e , e′ → p)

The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction 16^O (→ e , e′ → p) at a four-momentum transfer squared of 0.8 GeV2 in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton’s form factors in the nuclear medium.Mjerile su se uzdužna i poprečna komponenta polarizacije izlaznih protona u reakciji 16^O (→ e , e′ → p) za kvadrat prijenosa impulsa od 0.8 GeV2 , u kvazislobodnim kinematičkim uvjetima. Ovo su prva mjerenja prijenosa polarizacije za složenu jezgru. Usporedba omjera poprečne i uzdužne polarizacije s teorijskim predviđanjima omogućava proučavanje promjena faktora oblika protona kada je u nuklearnom okruženju

Flux profile scanners for scattered high-energy electrons

The paper describes the design and performance of flux integrating Cherenkov scanners with air-core reflecting light guides used in a high-energy, high-flux electron scattering experiment at the Stanford Linear Accelerator Center. The scanners were highly radiation resistant and provided a good signal to background ratio leading to very good spatial resolution of the scattered electron flux profile scans.Comment: 22 pages, 17 figure