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Subjective measurement of peripheral refraction
Get PDFThe quality of the peripheral image affects several visual aspects. In particular, eye shape, determined by peripheral refraction, has been shown to be an important factor associated with refractive error in children. For this reason, analysis of off-axis refractive error is one of the subjective measurements that should be performed during refractive procedures. Peripheral refraction refers to the
position of the focal point of light radiation reaching the eye when horizontal rays are focused on fovea, outside primary visual axis. Recent studies have found the peripheral refractive error plays an important role in the development of myopia: myopic individuals show hyperopic defocus unlike emmetropes or hyperopes, who have myopic defocus at the peripheral level; thus, in order to focus objects located in the peripheral visual field on the retina, the bulb is prone to elongation. The aim of the study was to develop a method for measuring peripheral refraction, accessible to all clinicians without special instruments, and that can be performed during the refractive examination to obtain an additional finding in addition to the central refractive data
Comparative analysis of tear film stability: Automated non-invasive and fluorescein tear break-up time
Get PDFThe tear film plays a crucial role in maintaining ocular surface physiology, with tear film stability being a key parameter. Tear break-up time (TBUT) is a common method for assessing tear film stability, involving the duration between a full blink and the initial disruption in the tear film. This study aimed to assess non-invasive break-up time (NIBUT) using an automatic approach and compare it with the traditional fluoresce in break-up time (fBUT) method. Forty-three non contact lens wearers were enrolled, and NIBUT data were collected using the Sirius+ instrument. fBUT was conducted using fluoresce in sodium strips. Test-retest measurements were performed with 2 hours delay. NIBUT values were consistently longer than fBUT values (14.8±8.0svs. 8.7±5.2s), aligning with existing literature. The results revealed good test-retest reliability for both methods; however, intra observer repeatability was weak. A potential limitation was the non-randomized sequence of measurements, with fBUT consistently performed at the end due to its
invasive nature. Variations in the coverage area of fBUT and NIBUT assessments, influenced by factors like the Placido disc dimension, and the lash shadows, may have contributed to shorter times with fBUT. Preliminary analyses focusing only on the corneal area covered by Sirius+ Placido rings supported this hypothesis. In summary, while NIBUT consistently showed longer values than fBUT, further
investigations considering limitations and potential influencing factors are warranted for a comprehensive understanding of tear film stability assessment
Methods and tools for generating the DTM of an archaeological site: the case-study of the photogrammetric survey of Nora (Sardinia, Italy)
No full textThis paper describes the high-resolution survey of the archaeological site of Nora (Sardinia, Italy) using the aerophotogrammetric technique. The survey was conducted in October 2021 on a 14-hectare peninsula located in the Gulf of Cagliari. Previous attempts to survey the area, aside from the 1 metre/pixel LiDAR survey carried out by the Region of Sardinia, have been hampered by the challenges posed by the size of the area and the costs involved. The Digital Terrain Model was obtained from the 3D model created with the Agisoft Metashape© software by removing the buildings and the vegetation. The segmentation process was carried out using Cloud Compare and the resulting DTM was then analysed using the geomorphological analysis tools provided by QGIS. The seabed DTM was obtained through several survey campaigns between 2013 and 2015, using the same software. The terrestrial DTM was merged with the seabed DTM, resulting in a comprehensive 3D and 2D model of the peninsula and its surroundings. The final DTM was printed with rapid prototyping technologies to explore its potential use as a tactile model for promotion and dissemination in the field
Heavy meson spectroscopy results at BESIII
Get PDFAlthough the charmonium spectrum seems to be well investigated, charmonia can still be used as benchmarks to test QCD predictions, as these states lie in the transition region between perturbative and non-perturbative QCD. Despite the need for experimental confirmations, slowdowns arise from limited statistics of the production of non-vector states. Indeed, some charmonium states’ masses,
widths and brancing fractions are still far from being precisely known. Since 2009, BESIII has been scanning and investigating the energy range between 2.0 and 4.9 GeV. Thanks to its largest data sets of charmonium resonances (J/ψ, ψ(2S), and ψ(3770)) in the world as well as other data sets at the centre-of-mass energies above 3.8 GeV, BESIII can overcome statistical limitations to shed light on open questions
Spectroscopy of heavy baryons
Get PDFWe present a study of mass spectra and electromagnetic couplings of S- and P-wave heavy baryons in the framework of a non-relativistic harmonic oscillator quark model. Particular attention is paid to the properties of heavy cascade baryons, ΞQ and Ξ Q
Search for exotic hadrons in at GlueX
Get PDFThe theoretical description of the strong interaction between quarks and gluons that form hadrons is provided by quantum chromodynamics. However, the impact of gluonic excitations on the characteristics of hadrons and their role in hadronic structure is yet to be determined. Recent discoveries of several possibly exotic hadrons highlight the significance of spectroscopic measurements in comprehending the nature of the strong interaction. These proceedings focus on the status of the hunt for exotic contributions in photoproduction data obtained with the GlueX experiment at Jefferson Lab in η()π systems. Specifically, we discuss the
investigation of the a2(1320) meson production in these key channels, which is an initial step towards identifying exotic quantum-number states, where gluonic excitations contribute to the external properties, called hybrid states. Furthermore, the discussion will cover the application of an amplitude analysis that exploits the polarization of the photon beam available to the GlueX experiment and its implications for identifying the lightest hybrid meson
Tensor glueball decay into nucleon-antinucleon
Get PDFIn the context of a chiral hadronic model, we compute the decay ratio of a tensor glueball decaying into a nucleon and antinucleon compared to the decay into 2 pions. Tensor meson dominance is assumed to also hold for the tensor glueball in order to relate the coupling constants of the different decay channels. We find that the decay width to nucleons is slightly larger than the decay width to pions, but still in the same order of magnitude
J/ψ photoproduction close to threshold at GlueX
Get PDFClose to threshold photoproduction γp → J/ψp probes small-size gluon configurations in the proton. Under certain assumptions, it allows us to study the proton properties, as gluonic GPDs, anomalous contribution to the mass of the
proton, gravitational form factors, and the mass radius of the proton. A careful comparison of the experimental data with the theoretical predictions would help us to verify the validity of those assumptions. The first cross-section measurements of near-threshold reaction γp → J/ψp by the GlueX Collaboration (Ali A. et al., Phys. Rev. Lett., 123 (2019) 072001) has attracted a considerable theoretical interest. Along with the relation to the gluonic properties of the proton, the measurement exploited a possibility of the LHCb Pentaquark (P) production in the s-channel of the observed reaction, placing a limit on the decay probability P → J/ψp. Here we present new GlueX results (Adhikari S. et al., Phys. Rev. C, 108 (2023) 025201) based on a four-times larger data set. The higher statistics, along with the full
acceptance of the GlueX spectrometer allows us to measure the differential crosssection in several energy ranges and compare the results with several theoretical calculations. The new results have already been used in a number of theoretical papers
Techniques for hadron spectroscopy studies at LHCb
Get PDFThe large heavy-flavor dataset collected by the LHCb experiment offers a good opportunity to investigate the inner structure of hadrons and helps to improve the knowledge of the strong interaction. With the ever larger data samples collected by LHCb, constant improvements of analysis methods are in demand, including for example advanced computing techinques to handle the huge data sample and the phenomenological tools to reduce the systematic uncertainties. Several selected developments in the past few years will be presented in this paper
Constraining the formation mechanisms of light (anti)nuclei at the LHC and applications for cosmic ray physics
Get PDFThe formation mechanism of light (anti)nuclei produced in highenergy hadronic collisions is an open question that is being addressed both theoretically and experimentally. Moreover, the study of (anti)nuclei production at particle accelerators is relevant to model the flux of antinuclei produced in cosmic ray interactions, which represents the dominant background for dark matter searches. According to the most accredited theoretical models, dark matter particles in the galactic halo could annihilate and produce ordinary matter-antimatter pairs. Thanks to its excellent particle identification capabilities, ALICE measured (anti)nuclei in all the collision systems and energies provided by the LHC. Measurements of transverse momentum distributions, ratios of integrated yields, and coalescence probabilities are discussed in these proceedings in comparison with two phenomenological models used to describe the production of nuclei. The performance of the upgraded ALICE detector during the proton proton data taking in
Run 3 is discussed together with perspectives on new applications to indirect dark matter searches by the AMS experiment