ABSTRACT
The space-charge field of a relativistic charged bunch propagating in plasma is screened due to the presence of mobile charge carriers. We experimentally investigate such screening by measuring the effect of dielectric wakefields driven by the bunch in a uncoated dielectric capillary where the plasma is confined. We show that the plasma screens the space-charge field and therefore suppresses the dielectric wakefields when the distance between the bunch and the dielectric surface is much larger than the plasma skin depth. Before full screening is reached, the effects of dielectric and plasma wakefields are present simultaneously.
ABSTRACT
Plasma wakefield acceleration represented a breakthrough in the field of particle accelerators by pushing beams to gigaelectronvolt energies within centimeter distances. The large electric fields excited by a driver pulse in the plasma can efficiently accelerate a trailing witness bunch paving the way toward the realization of laboratory-scale applications like free-electron lasers. However, while the accelerator size is tremendously reduced, upstream and downstream of it the beams are still handled with conventional magnetic optics with sizable footprints and rather long focal lengths. Here we show the operation of a compact device that integrates two active-plasma lenses with short focal lengths to assist the plasma accelerator stage. We demonstrate the focusing and energy gain of a witness bunch whose phase space is completely characterized in terms of energy and emittance. These results represent an important step toward the accelerator miniaturization and the development of next-generation table-top machines.
ABSTRACT
We present a new approach that demonstrates the deflection and guiding of relativistic electron beams over curved paths by means of the magnetic field generated in a plasma-discharge capillary. We experimentally prove that the guiding is much less affected by the beam chromatic dispersion with respect to a conventional bending magnet and, with the support of numerical simulations, we show that it can even be made dispersionless by employing larger discharge currents. This proof-of-principle experiment extends the use of plasma-based devices, that revolutionized the field of particle accelerators enabling the generation of GeV beams in few centimeters. Compared to state-of-the-art technology based on conventional bending magnets and quadrupole lenses, these results provide a compact and affordable solution for the development of next-generation tabletop facilities.
ABSTRACT
A Meckel's cave tumor poses a great challenge because of the peculiar neurovascular structure of the area and the deep location. Multiple surgical approaches have been designed for this area. In this report, we describe a case treated with a combined one step single piece fronto-temporo-orbito-zygomatic craniotomy (FTOZ) endoscopic-assisted approach for the treatment of an epidermoid tumor of Meckel's cave. A 51-year-old woman presented with a clinical history of left trigeminal neuralgia and paresthesia. CT imaging revealed a left basal temporal tumor. MR showed a tumor located in Meckel's cave near the cavernous sinus, with a good enhancement after gadolinium administration. The tumor was resected through a lateral basal subtemporal extradural approach followed by an intradural approach using intraoperative neuronavigation, endoscopic assistance, neurophysiological monitoring, and an intraoperative ultrasound probe. The lesion was completely removed. No new onset neurological damage has occurred. The symptoms improved following surgery. The aesthetic appearance of the patient was respected. The combined approach with a single piece fronto-temporo-orbito-zygomatic craniotomy has enabled us to work on a wider operating field to completely remove the lesion avoiding blind spots.
Subject(s)
Neoplasms , Female , Humans , Middle Aged , Craniotomy , NeuronavigationABSTRACT
Odontoid fractures, frequently observed in patients over the age of 70, often involve the base of the axis (Anderson-D'Alonzo type 2). For surgical treatment, posterior C1-C2 fixation is the traditional method, whose fusion rates range between 93 and 100%. However, morbidity and mortality rates are high. In addition, cervical motion, especially axial rotation, is postoperatively reduced. Nakanishi and Bohler introduced the anterior screw fixation approach for the surgical treatment of odontoid fracture type II. This procedure preserves the atlantoaxial complex motion, provides immediate stability and high fracture healing rates, and, most importantly, has a low incidence of complications with good fusion rates. The surgical strategy must take into account the patient's anatomy, the morphological characteristics of the fracture, the quality of the bone, and any concomitant injuries. In this chapter, we describe a C2 type II fracture treated via a neuronavigated anterior retropharyngeal approach.
Subject(s)
Odontoid Process , Humans , Odontoid Process/diagnostic imaging , Odontoid Process/surgery , Bone Screws , Neck , RotationABSTRACT
The aim of this study was to determine the relationship between cervical spine sagittal alignment and clinical outcomes after using a standalone intersomatic titanium cage CeSPACE for anterior cervical discectomy and arthrodesis. We present our clinical experience in a group of 180 patients with a mean follow-up for at least 2 years. Patients were evaluated by clinical and radiological assessment preoperatively, immediately after surgery and at regular follow-up. There were 97 male and 83 female patients (average age: 56.6 years) who were preoperatively affected by cervical radiculomyelopathy that was due to spondylosis or cervical disk herniation and who underwent surgical treatment. All patients underwent an anterior discectomy and interbody fusion through the positioning of one or more levels of the CeSPACE device. Compared with the preoperative scores, improvement was seen in postoperative visual analog scale (VAS) scores and Neck Disability Index (NDI) values. The standalone intersomatic titanium cage CeSPACE for anterior cervical discectomy and arthrodesis improved radiculomyelopathy and increased the probability of cervical kyphotic alignment. However, cervical sagittal alignment after surgery was not significantly associated with clinical outcomes in terms of postoperative improvement in VAS scores and NDI values. Similarly, the change in cervical sagittal alignment was not related to visual analog scale scores or Neck Disability Index values.
Subject(s)
Spondylosis , Titanium , Humans , Female , Male , Middle Aged , Diskectomy , Cervical Vertebrae/diagnostic imaging , Cervical Vertebrae/surgery , Neck , Spondylosis/diagnostic imaging , Spondylosis/surgeryABSTRACT
COVID-19 pandemic had an impact on surgical activities. The aim of this multi-centric, retrospective study was to evaluate the impact of the COVID-19 pandemic on breast surgery. The patients who operated during the pre-pandemic year 2019 were compared to those operated in 2020. Fourteen Breast Care Units provided data on breast surgical procedures performed in 2020 and 2019: total number of breast-conserving surgery (BCS), number of 1st level oncoplastic breast surgery (OBS), number of 2nd level OBS; total number of mastectomies, mastectomies without reconstruction, mastectomies with a tissue expander, mastectomies with direct to implant (DTI) reconstruction, mastectomies with immediate flap reconstruction; total number of delayed reconstructions, number of expanders to implant reconstructions, number of delayed flap reconstructions. Overall 20.684 patients were included: 10.850 (52.5%) operated during 2019, and 9.834 (47.5%) during 2020. The overall number of breast oncologic surgical procedures in all centers in 2020 was 8.509, compared to 9.383 in 2019 (- 9%). BCS decreased by 744 cases (- 13%), the overall number of mastectomies decreased by 130 cases (- 3.5%); mastectomy-BCS ratio was 39-61% in 2019, and 42-58% in 2020. Regarding immediate reconstructive procedures mastectomies with DTI reconstruction increased by 166 cases (+ 15%) and mastectomies with immediate expander reconstruction decreased by 297 cases (- 20%). Breast-delayed reconstructive procedures in all centers in 2020 were 142 less than in 2019 (- 10%). The outburst of the COVID-19 pandemic in 2020 determined an implemented number of mastectomies compared to BCS, an implemented number of immediate breast reconstructions, mainly DTI, and a reduction of expander reconstruction.
Subject(s)
Breast Neoplasms , COVID-19 , Mammaplasty , Humans , Female , Mastectomy , Retrospective Studies , Pandemics , Breast Neoplasms/surgery , Mammaplasty/methodsABSTRACT
In hydrogeological research, the systematic and periodic measurement of the piezometric level is fundamental to assess aquifer storage, identify recharge and discharge areas, define flow directions and to infer the balance between inputs and withdrawals. Furthermore, knowledge of this variable and its fluctuations is essential for the efficient management and protection of groundwater resources. In this work, a novel methodology is proposed for the remote acquisition of piezometric information from traditional large-diameter wells, using drone-borne LiDAR observations. The workflow developed consists of different stages, from flight planning and parameter setting, to point cloud generation, data processing and validation and its statistical treatment to extract piezometric information. This methodology has been applied in a small coastal aquifer with numerous wells that have served as monitoring points. The UAV-LiDAR has enabled the straightforward obtention of measurements of the piezometric level with very high vertical accuracies (RMSE of 5 cm) with minimum and maximum residuals of -8.7 and 7.9 cm respectively. Likewise, the method has shown vertical accuracies 3 times better than those inferred from the official DTM of best resolution available in Spain, which is usually used in hydrogeological works. Since the technique provides absolute values of the piezometric level, it eliminates the need for laborious levelling work prior to hydrogeological campaigns. This method has proved to be an effective alternative/complementary technique to traditional measurements of the piezometric level, allowing to monitor extensive or inaccessible areas over short periods of time and to potentially reduce gaps in hydrogeological databases.
Subject(s)
Environmental Monitoring , Groundwater , Environmental Monitoring/methods , Water Wells , SpainABSTRACT
This paper sheds light on the time structure of betatron radiation, emitted by electrons that undergo betatron oscillations as they accelerate under the action of plasma wakefields. It is a common practice to assume that the betatron pulses are as short as the electron bunch length, however we show that this is not a general rule. Indeed, the betatron pulse length is affected by the betatron motion, which stretches and modulates the radiation pulses already at the source level. Propagation in a vacuum, therefore, can greatly lengthen the betatron pulses by orders of magnitude. In the wake of the above, the coherent emission of betatron radiation is studied. Coherent betatron radiation has been found to propagate in an underdense region created by ponderomotive forces, thus not suppressed by the overdense plasma absorption. This could be observed experimentally, revealing information on the acceleration process and on key beam parameters.
ABSTRACT
Photoemission is one of the fundamental processes that describes the generation of charged particles from materials irradiated by photons. The continuous progress in the development of ultrashort lasers allows investigation into the dynamics of the process at the femtosecond timescale. Here we report about experimental measurements using two ultrashort ultraviolet laser pulses to temporally probe the electrons release from a copper cathode in a radio-frequency photoinjector. By changing their relative delay, we studied how the release mechanism is affected by two-photon photoemission when tens of GW/cm2 intensities are employed. We evaluated the limits it poses on the achievable beam brightness and analyzed the resulting emission yield in terms of the electronic temperature by modeling the cathode as a two-temperature system.
ABSTRACT
In this work, we theoretically study the transduction of orbital angular momentum (OAM) l for infrared pump lasers into the THz domain. In the case of optical rectification, the transduction of OAM occurs only through a spin-orbit interaction, with the selection rule on the OAM l=0 valid for any kind of polarization of the pump, which means that there is no transfer of OAM along the propagation axis. In difference frequency generation, the selection rule for the difference Δl between the OAM of the pump fields with linear or circular polarization is l=Δl, whereas l ranges from Δl-2 to Δl+2 in cases of both radial and azimuthal polarization. Moreover, for THz generation in the latter case, the high diffraction obtained with tightly focused pumps yields l tending to Δl±2, while l tends to zero in the opposite case of large pump beams.
ABSTRACT
OBJECTIVE: The primary aim is to verify the effectiveness of an aquatic training (AT) in inpatients with severe Traumatic Brain Injury (sTBI) on balance. The secondary aims are to explore the effects on gait, activities of daily living, and quality of life, comparing to a land-based conventional protocol. METHODS: Two-arm, randomized controlled trial. Twenty inpatients with sTBI, Glasgow Coma Scale score ≤8, and Level of Cognitive Functioning ≥7 were recruited and randomly assigned to the aquatic therapy group (ATG) or to the Conventional Training Group (CTG). Patients underwent 12 individual rehabilitation sessions (3 days/week, 4 weeks), in a rehabilitation pool during the post-acute intensive neurorehabilitation. The primary outcome measure was the Berg Balance Scale (BBS). Secondary outcome measures were the Modified Barthel Index (MBI), Disability Rating Scale (DRS), Tinetti Gait Balance Scale (TBG) and Quality of Life After Brain Injury (QOLIBRI). All the evaluations were performed at the baseline and after 4 weeks of training. RESULTS: The within-subjects analysis showed a significant improvement both in ATG and CTG in MBI, BBS, TBG, and QOLIBRI. CONCLUSION: Our results may support the use of AT during post-acute phase to improve motor functions and quality of life in patients with sTBI.
Subject(s)
Brain Injuries, Traumatic , Neurological Rehabilitation , Activities of Daily Living , Brain Injuries, Traumatic/complications , Exercise Therapy , Humans , Postural Balance , Quality of Life , Single-Blind Method , Treatment OutcomeABSTRACT
OBJECTIVE: Iron deficiency anemia (IDA) in patients with heart disease is correlated with decreased exercise capacity and poor health-related quality of life, and predicts worse cardiovascular outcomes, especially for elderly patients. IDA can worsen cardiac function that can be monitored with Heart Rate Variability (HRV) analysis, providing important information about cardiac health. In a recent study we explored the effect and the tolerability of the administration of Ferric Sodium EDTA in combination with vitamin C, folic acid, copper gluconate, zinc gluconate and selenomethionine (Ferachel Forte®) in "frailty" patients with secondary anemia and low kidney failure, by analysing the HRV frequency domain. The aim of the present study is the further confirmation of the safety of the already evaluated intervention, by analysing non-linear domain of HRV. PATIENTS AND METHODS: In this pilot study we enrolled 52 "frailty" elderly patients, with a recent diagnosis of secondary anemia due to iron deficiency, with Class II New York Heart Association (NYHA) hypertensive heart disease, low kidney failure, and atherosclerosis. The patients were divided in 2 groups: Group A (N=23 patients) received oral administration of Ferric Sodium EDTA in combination with vitamin C, folic acid, copper gluconate, zinc gluconate and selenomethionine (Ferachel Forte®) 2 tabs/day, containing 60 mg of Fe3+, for 24 days; Group B (N=29 patients) received intravenous administration of ferrous gluconate 63 mg/day added to saline solution, while they were hospitalized (15±5 days). We evaluated laboratory values of hemoglobin (Hb) and sideremia levels. Furthermore, we measured ECG signals before and after treatment, using non-linear analysis techniques. RESULTS: Both intravenous and oral treatments evaluated in this study, were effective and safe about the cardiovascular risk in "frailty" elderly patients, as resulted from non-linear HRV analysis. Efficacy results showed that hemoglobin and sideremia levels after treatments are significantly increased. The HRV non-linear analysis showed that all parameters evaluated, except for the SD1 values in the Group A, were not affected by treatments, confirming the absence of cardiovascular risk of the therapy. CONCLUSIONS: Non-linear HRV evaluation confirmed that oral administration of Ferric Sodium EDTA, in combination with vitamin C, folic acid, copper gluconate, zinc gluconate and selenomethionine (Ferachel forte®) did not impact the cardiovascular risk, without causing adverse events typically reported with other iron supplementation therapies, both oral and intravenous.
Subject(s)
Anemia, Iron-Deficiency/drug therapy , Ascorbic Acid/therapeutic use , Ferric Compounds/therapeutic use , Folic Acid/therapeutic use , Frailty/complications , Gluconates/therapeutic use , Heart Diseases/complications , Heart Rate/drug effects , Iron Chelating Agents/therapeutic use , Selenomethionine/therapeutic use , Aged , Aged, 80 and over , Anemia, Iron-Deficiency/blood , Anemia, Iron-Deficiency/complications , Anemia, Iron-Deficiency/diagnosis , Ascorbic Acid/adverse effects , Drug Combinations , Edetic Acid/adverse effects , Edetic Acid/therapeutic use , Female , Ferric Compounds/adverse effects , Folic Acid/adverse effects , Frail Elderly , Frailty/diagnosis , Frailty/physiopathology , Gluconates/adverse effects , Heart Disease Risk Factors , Heart Diseases/diagnosis , Heart Diseases/physiopathology , Humans , Iron Chelating Agents/adverse effects , Male , Pilot Projects , Renal Insufficiency/complications , Renal Insufficiency/diagnosis , Renal Insufficiency/physiopathology , Risk Assessment , Selenomethionine/adverse effects , Time Factors , Treatment OutcomeABSTRACT
A self-consistent analytic formalism of the description of saturation effects in optical rectification is provided. It is shown that a nonlinear absorption term arises from this process that is dominant over two-photon absorption, deriving instead from the nonlinear susceptibility of the third order. An analytical expression for the saturation intensity is provided and compared to experiments in literature. Moreover, it is shown how the saturation effects modify the transfer of the pump spectral phase and amplitude into the terahertz domain.
ABSTRACT
In this paper, we show how plasma discharge capillaries can be numerically modeled as resistors within an RLC-series discharge circuit, allowing for a simple description of these systems, while taking into account heat and radiation losses. An analytic radial model is also provided and compared to the numerical model for plasma discharge capillaries at thermal equilibrium, with corrections due to radiation losses. Finally, diagnostic techniques based on visible spectroscopy of plasma emission lines are discussed both for atomic and molecular gases, comparing experimental results with numerical simulations and theoretical calculations.
ABSTRACT
In this erratum Fig. 3 of Opt. Lett.44, 1011 (2019)OPLEDP0146-959210.1364/OL.44.001011 has been updated. A diagnostic method for the electron plasma density and temperature based on the exploitation of wide-band THz pulses is presented. The model accompanying the diagnostic method is described and it is shown useful to characterize the plasma density and temperature profile along a symmetry axis. This diagnostic is particularly interesting for plasma-acceleration schemes or laser-produced plasma channels.
ABSTRACT
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
ABSTRACT
The Río Tinto mining area provides ideal conditions for studying the role of colloidal particles in concentrating. All the elements are present in higher concentrations respect to their content in common natural waters. 234U/238U activity ratio ranges between 2.286⯱â¯0.149 and 2.531⯱â¯0.151. Concentration of Fe and Al are in the order of 104-103â¯mg/L; Co, Zn and Cu values are three times lower than Fe and Al, but still much greater than in natural waters; U reaches values up to 40.73⯵g/L. To evaluate the partitioning of these elements into the colloidal fraction, ultrafiltration (UF) experiments were made. A permeation model describing the relationship between concentration of the elements or isotopes in the permeate solution and the concentration factor (CF) was calculated. Experiments were carried out using CF from 1.5 to 25.0. The behaviour of investigated heavy metals and U can be predicted by a permeation model that provides similar permeation coefficient (Pc) for all of them (Pcâ¯=â¯0.95-0.97 for 50â¯kDa, Pcâ¯=â¯0.86-0.88 for 10â¯kDa, and Pcâ¯=â¯0.80-0.86 for 3â¯kDa). Retention for all the investigated elements occurs, resulting in up to 23% of the element associated to the 3â¯kDa colloidal fraction. The increase in U and heavy metals concentrations in the retentate fraction with the increasing CF is due to the retention of the colloidal fraction. The colloidal abundance of related metals increased with decreasing membrane MWCO even though the difference is small between 3 and 10â¯kDa fraction for some metals Characterization of colloidal material is needed to better understand the state of play in this context.
Subject(s)
Metals, Heavy , Mining , SpainABSTRACT
A diagnostic method for the electron plasma density and temperature based on the exploitation of wideband THz pulses is presented. The model accompanying the diagnostic method is described, and it is shown useful to characterize the plasma density and temperature profile along a symmetry axis. This diagnostic is particularly interesting for plasma-acceleration schemes or laser-produced plasma channels.