Vaginal Malignant Melanoma: Case Report and Review of the Literature

Introduction

Primary vaginal malignant melanomas are rare tumours with a limited number of cases published in the literature. They primarily affect post-menopausal women with a median age of 57–68 years and have a dismal prognosis. The 5-year survival rate, regardless of treatment, is approximately 5–25%.

Case description

We present the case of an 87-year-old female who presented with haematuria and urinary incontinence. She was diagnosed with AJCC stage IIIC vaginal melanoma. Considering her age and the extent of malignancy, surgery was not a viable option and immunotherapy with nivolumab and ipilimumab was initiated as treatment.

Discussion

The diagnosis of vaginal melanomas includes pathological analysis and immunohistochemistry (IHC) of the mass, imaging to determine extent, and genetic testing. Surgery is the preferred treatment in suitable cases. For metastatic or unresectable cases, immunotherapy or targeted therapy is the preferred first-line treatment. Due to the lack of an adequate number of cases to conduct randomized clinical trials, prognostic factors and treatment protocols for vaginal melanomas are not clearly defined. At present, the management of these tumours is largely based on retrospective studies and anecdotal evidence accompanied by significant knowledge gaps. Our case will be a valuable addition to the existing literature on vaginal melanomas that are managed non-surgically.

LEARNING POINTS

The effect of chemical representation on active machine learning towards closed-loop optimization

Multivariate chemical reaction optimization involving catalytic systems is a non-trivial task due to the high number of tuneable parameters and discrete choices.

Telemedicine Physical Examination Utilizing a Consumer Device Demonstrates Poor Concordance with In-Person Physical Examination in Emergency Department Patients with Sore Throat: A Prospective Blinded Study

BACKGROUND

Telemedicine allows patients to connect with healthcare providers remotely. It has recently expanded to evaluate low-acuity illnesses such as pharyngitis by using patients' personal communication devices. The purpose of our study was to compare the telemedicine-facilitated physical examination with an in-person examination in emergency department (ED) patients with sore throat.

MATERIALS AND METHODS

This was a prospective, observational, blinded diagnostic concordance study of patients being seen for sore throat in a 60,000-visit Midwestern academic ED. A telemedicine and a face-to-face examination were performed independently by two advanced practice providers (APP), blinded to the results of the other evaluator. The primary outcome was agreement on pharyngeal redness between the evaluators, with secondary outcomes of agreement and inter-rater reliability on 14 other aspects of the pharyngeal physical examination. We also conducted a survey of patients and providers to evaluate perceptions and preferences for sore throat evaluation using telemedicine.

RESULTS

Sixty-two patients were enrolled, with a median tonsil size of 1.0. Inter-rater agreement (kappa) for tonsil size was 0.394, which was worse than our predetermined concordance threshold. Other kappa values ranged from 0 to 0.434, and telemedicine was best for detecting abnormal coloration of the palate and tender superficial cervical lymph nodes (anterior structures), but poor for detecting abnormal submandibular lymph nodes or asymmetry of the posterior pharynx (posterior structures). In survey responses, telemedicine was judged easier to use and more comfortable for providers than patients; however, neither patients nor providers preferred in-person to telemedicine evaluation.

CONCLUSION

Telemedicine exhibited poor agreement with the in-person physical examination on the primary outcome of tonsil size, but exhibited moderate agreement on coloration of the palate and cervical lymphadenopathy. Future work should better characterize the importance of the physical examination in treatment decisions for patients with sore throat and the use of telemedicine in avoiding in-person healthcare visits.

Testing Hadronic Interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_{CM}=110-170  TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.

Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8±0.7(stat)±6.7(syst)  MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.

Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield

Electrical breakdown sets a limit on the kinetic energy that particles in a conventional radio-frequency accelerator can reach. New accelerator concepts must be developed to achieve higher energies and to make future particle colliders more compact and affordable. The plasma wakefield accelerator (PWFA) embodies one such concept, in which the electric field of a plasma wake excited by a bunch of charged particles (such as electrons) is used to accelerate a trailing bunch of particles. To apply plasma acceleration to electron-positron colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas. Although substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFAs where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered--'self-loaded'--so that about a billion positrons gain five gigaelectronvolts of energy with a narrow energy spread over a distance of just 1.3 metres. They extract about 30 per cent of the wake's energy and form a spectrally distinct bunch with a root-mean-square energy spread as low as 1.8 per cent. This ability to transfer energy efficiently from the front to the rear within a single positron bunch makes the PWFA scheme very attractive as an energy booster to an electron-positron collider.

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with [Formula: see text] eV by analyzing cosmic rays with energies above [Formula: see text] eV arriving within an angular separation of approximately 15[Formula: see text]. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

Experimental demonstration of a soft x-ray self-seeded free-electron laser

The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using a grating monochromator system. We report the demonstration of soft x-ray self-seeding with a measured resolving power of 2000-5000, wavelength stability of 10(-4), and an increase in peak brightness by a factor of 2-5 across the photon energy range of 500-1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50-fold higher brightness to users.

Beam loading by distributed injection of electrons in a plasma wakefield accelerator

We show through experiments and supporting simulations that propagation of a highly relativistic and dense electron bunch through a plasma can lead to distributed injection of electrons, which depletes the accelerating field, i.e., beam loads the wake. The source of the injected electrons is ionization of the second electron of rubidium (Rb II) within the wake. This injection of excess charge is large enough to severely beam load the wake, and thereby reduce the transformer ratio T. The reduction of the average T with increasing beam loading is quantified for the first time by measuring the ratio of peak energy gain and loss of electrons while changing the beam emittance. Simulations show that beam loading by Rb II electrons contributes to the reduction of the peak accelerating field from its weakly loaded value of 43  GV/m to a strongly loaded value of 26  GV/m.

Generating periodic terahertz structures in a relativistic electron beam through frequency down-conversion of optical lasers

We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow band THz sources.

Measurement of the proton-air cross section at √s=57 TeV with the Pierre Auger Observatory

We report a measurement of the proton-air cross section for particle production at the center-of-mass energy per nucleon of 57 TeV. This is derived from the distribution of the depths of shower maxima observed with the Pierre Auger Observatory: systematic uncertainties are studied in detail. Analyzing the tail of the distribution of the shower maxima, a proton-air cross section of [505±22(stat)(-36)(+28)(syst)] mb is found.

Evidence of high harmonics from echo-enabled harmonic generation for seeding x-ray free electron lasers

Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science.

Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.

Observation of ultrahigh-energy cosmic rays with the ANITA balloon-borne radio interferometer

We report the observation of 16 cosmic ray events with a mean energy of 1.5 × 10¹⁹ eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2° for the event arrival directions.

Demonstration of the echo-enabled harmonic generation technique for short-wavelength seeded free electron lasers

We report the first experimental demonstration of the echo-enabled harmonic generation technique, which holds great promise for generation of high-power, fully coherent short-wavelength radiation. In this experiment, coherent radiation at the 3rd and 4th harmonics of the second seed laser is generated from the so-called beam echo effect. The experiment confirms the physics behind this technique and paves the way for applying the echo-enabled harmonic generation technique for seeded x-ray free electron lasers.

New limits on the ultrahigh energy cosmic neutrino flux from the ANITA experiment

We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of E(nu) approximately 3 x 10(18) eV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultrahigh energy extensive air showers.

Halo formation and emittance growth of positron beams in plasmas

An ultrarelativistic 28.5 GeV, 700-microm-long positron bunch is focused near the entrance of a 1.4-m-long plasma with a density n(e) between approximately equal to 10(13) and approximately equal to 5 x 10(14) cm(-3). Partial neutralization of the bunch space charge by the mobile plasma electrons results in a reduction in transverse size by a factor of approximately equal to 3 in the high emittance plane of the beam approximately equal to 1 m downstream from the plasma exit. As n(e) increases, the formation of a beam halo containing approximately 40% of the total charge is observed, indicating that the plasma focusing force is nonlinear. Numerical simulations confirm these observations. The bunch with an incoming transverse size ratio of approximately 3 and emittance ratio of approximately 5 suffers emittance growth and exits the plasma with approximately equal sizes and emittances.

Breakdown limits on Gigavolt-per-meter electron-beam-driven wakefields in dielectric structures

First measurements of the breakdown threshold in a dielectric subjected to GV/m wakefields produced by short (30-330 fs), 28.5 GeV electron bunches have been made. Fused silica tubes of 100 microm inner diameter were exposed to a range of bunch lengths, allowing surface dielectric fields up to 27 GV/m to be generated. The onset of breakdown, detected through light emission from the tube ends, is observed to occur when the peak electric field at the dielectric surface reaches 13.8+/-0.7 GV/m. The correlation of structure damage to beam-induced breakdown is established using an array of postexposure inspection techniques.

Observation of polarized positrons from an undulator-based source

An experiment (E166) at the Stanford Linear Accelerator Center has demonstrated a scheme in which a multi-GeV electron beam passed through a helical undulator to generate multi-MeV, circularly polarized photons which were then converted in a thin target to produce positrons (and electrons) with longitudinal polarization above 80% at 6 MeV. The results are in agreement with GEANT4 simulations that include the dominant polarization-dependent interactions of electrons, positrons, and photons in matter.

Hosing instability in the blow-out regime for plasma-wakefield acceleration

The electron hosing instability in the blow-out regime of plasma-wakefield acceleration is investigated using a linear perturbation theory about the electron blow-out trajectory in Lu et al. [in Phys. Rev. Lett. 96, 165002 (2006)10.1103/PhysRevLett.96.165002]. The growth of the instability is found to be affected by the beam parameters unlike in the standard theory Whittum et al. [Phys. Rev. Lett. 67, 991 (1991)10.1103/PhysRevLett.67.991] which is strictly valid for preformed channels. Particle-in-cell simulations agree with this new theory, which predicts less hosing growth than found by the hosing theory of Whittum et al.

Observations of the Askaryan effect in ice

We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation of the Askaryan effect in ice. As part of the complete validation process for the ANITA experiment, we performed an experiment at the Stanford Linear Accelerator Center in June 2006 using a 7.5 metric ton ice target. We measure for the first time the large-scale angular dependence of the radiation pattern, a major factor in determining the solid-angle acceptance of ultrahigh-energy neutrino detectors.

Ionization-induced electron trapping in ultrarelativistic plasma wakes

The onset of trapping of electrons born inside a highly relativistic, 3D beam-driven plasma wake is investigated. Trapping occurs in the transition regions of a Li plasma confined by He gas. Li plasma electrons support the wake, and higher ionization potential He atoms are ionized as the beam is focused by Li ions and can be trapped. As the wake amplitude is increased, the onset of trapping is observed. Some electrons gain up to 7.6 GeV in a 30.5 cm plasma. The experimentally inferred trapping threshold is at a wake amplitude of 36 GV/m, in good agreement with an analytical model and PIC simulations.

Positron production by x rays emitted by betatron motion in a plasma wiggler

Positrons in the energy range of 3-30 MeV, produced by x rays emitted by betatron motion in a plasma wiggler of 28.5 GeV electrons from the SLAC accelerator, have been measured. The extremely high-strength plasma wiggler is an ion column induced by the electron beam as it propagates through and ionizes dense lithium vapor. X rays in the range of 1-50 MeV in a forward cone angle of 0.1 mrad collide with a 1.7 mm thick tungsten target to produce electron-positron pairs. The positron spectra are found to be strongly influenced by the plasma density and length as well as the electron bunch length. By characterizing the beam propagation in the ion column these influences are quantified and result in excellent agreement between the measured and calculated positron spectra.

Hose instability and wake generation by an intense electron beam in a self-ionized gas

The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.

Multi-GeV energy gain in a plasma-wakefield accelerator

A plasma-wakefield accelerator has accelerated particles by over 2.7 GeV in a 10 cm long plasma module. A 28.5 GeV electron beam with 1.8 x 10(10) electrons is compressed to 20 microm longitudinally and focused to a transverse spot size of 10 microm at the entrance of a 10 cm long column of lithium vapor with density 2.8 x 10(17) atoms/cm3. The electron bunch fully ionizes the lithium vapor to create a plasma and then expels the plasma electrons. These electrons return one-half plasma period later driving a large amplitude plasma wake that in turn accelerates particles in the back of the bunch by more than 2.7 GeV.

Observation of parity nonconservation in møller scattering

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).

Future possibilities of the Linac Coherent Light Source

A study of the potential for the development of the Linac Coherent Light Source (LCLS) beyond the specifications of the baseline design is presented. These future developments include delivery of X-ray pulses in the 1 fs regime, extension of the spectral range, increase of the FEL power, exploitation of the spontaneous emission, and a more flexible time structure. As this potential is exploited, the LCLS can maintain its role as a world-leading instrument for many years beyond its commissioning in 2008 and initial operation as the world's first X-ray free-electron laser.

Femtosecond and subfemtosecond x-ray pulses from a self-amplified spontaneous-emission-based free-electron laser

We propose a novel method to generate femtosecond and subfemtosecond photon pulses in a free-electron laser by selectively spoiling the transverse emittance of the electron beam. Its merits are simplicity and ease of implementation. When the system is applied to the Linac Coherent Light Source, it can provide x-ray pulses the order of 1 fs in duration containing about 10(10) transversely coherent photons.

Plasma-wakefield acceleration of an intense positron beam

Plasma wakefields are both excited and probed by propagating an intense 28.5 GeV positron beam through a 1.4 m long lithium plasma. The main body of the beam loses energy in exciting this wakefield while positrons in the back of the same beam can be accelerated by the same wakefield as it changes sign. The scaling of energy loss with plasma density as well as the energy gain seen at the highest plasma density is in excellent agreement with simulations.

Ultrarelativistic-positron-beam transport through meter-scale plasmas

We report on the first study of the dynamic transverse forces imparted to an ultrarelativistic positron beam by a long plasma in the underdense regime. Focusing of the 28.5 GeV beam is observed from time-resolved beam profiles after the 1.4 m plasma. The strength of the imparted force varies along the approximately 12 ps full length of the bunch as well as with plasma density. Computer simulations substantiate the longitudinal aberration seen in the data and reveal mechanisms for emittance degradation.

Transverse envelope dynamics of a 28.5-GeV electron beam in a long plasma

The transverse dynamics of a 28.5-GeV electron beam propagating in a 1.4 m long, (0-2)x10(14) cm(-3) plasma are studied experimentally in the underdense or blowout regime. The transverse component of the wake field excited by the short electron bunch focuses the bunch, which experiences multiple betatron oscillations as the plasma density is increased. The spot-size variations are observed using optical transition radiation and Cherenkov radiation. In this regime, the behavior of the spot size as a function of the plasma density is well described by a simple beam-envelope model. Dynamic changes of the beam envelope are observed by time resolving the Cherenkov light.

X-ray emission from betatron motion in a plasma wiggler

The successful utilization of an ion channel in a plasma to wiggle a 28.5-GeV electron beam to obtain broadband x-ray radiation is reported. The ion channel is induced by the electron bunch as it propagates through an underdense 1.4-meter-long lithium plasma. The quadratic density dependence of the spontaneously emitted betatron x-ray radiation and the divergence angle of approximately (1-3)x10(-4) radian of the forward-emitted x-rays as a consequence of betatron motion in the ion channel are in good agreement with theory. The absolute photon yield and the peak spectral brightness at 14.2-keV photon energy are estimated.