Stable Operation of a Free-Electron Laser Driven by a Plasma Accelerator

The breakthrough provided by plasma-based accelerators enabled unprecedented accelerating fields by boosting electron beams to gigaelectronvolt energies within a few centimeters [1-4]. This, in turn, allows the realization of ultracompact light sources based on free-electron lasers (FELs) [5], as demonstrated by two pioneering experiments that reported the observation of self-amplified spontaneous emission (SASE) driven by plasma-accelerated beams [6,7]. However, the lack of stability and reproducibility due to the intrinsic nature of the SASE process (whose amplification starts from the shot noise of the electron beam) may hinder their effective implementation for user purposes. Here, we report a proof-of-principle experiment using plasma-accelerated beams to generate stable and reproducible FEL light seeded by an external laser. FEL radiation is emitted in the infrared range, showing the typical exponential growth of its energy over six consecutive undulators. Compared to SASE, the seeded FEL pulses have energies 2 orders of magnitude larger and stability that is 3 times higher.

Free-electron lasing with compact beam-driven plasma wakefield accelerator

The possibility to accelerate electron beams to ultra-relativistic velocities over short distances by using plasma-based technology holds the potential for a revolution in the field of particle accelerators^1-4. The compact nature of plasma-based accelerators would allow the realization of table-top machines capable of driving a free-electron laser (FEL)⁵, a formidable tool to investigate matter at the sub-atomic level by generating coherent light pulses with sub-ångström wavelengths and sub-femtosecond durations^6,7. So far, however, the high-energy electron beams required to operate FELs had to be obtained through the use of conventional large-size radio-frequency (RF) accelerators, bound to a sizeable footprint as a result of their limited accelerating fields. Here we report the experimental evidence of FEL lasing by a compact (3-cm) particle-beam-driven plasma accelerator. The accelerated beams are completely characterized in the six-dimensional phase space and have high quality, comparable with state-of-the-art accelerators⁸. This allowed the observation of narrow-band amplified radiation in the infrared range with typical exponential growth of its intensity over six consecutive undulators. This proof-of-principle experiment represents a fundamental milestone in the use of plasma-based accelerators, contributing to the development of next-generation compact facilities for user-oriented applications⁹.

Focusing of High-Brightness Electron Beams with Active-Plasma Lenses

Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.

Identification of a New Mullet Species Complex Based on an Integrative Molecular and Cytogenetic Investigation of Mugil hospes (Mugilidae: Mugiliformes)

Mullets are very common fishes included in the family Mugilidae, (Mugiliformes), which are characterized by both a remarkably uniform external morphology and internal anatomy. Recently, within this family, different species complexes were molecularly identified within Mugil, a genus which is characterized by lineages that sometimes show very different karyotypes. Here we report the results of cytogenetic and molecular analyses conducted on Mugil hospes, commonly known as the hospe mullet, from Ecuador. The study aims to verify whether the original described species from the Pacific Ocean corresponds to that identified in the Atlantic Ocean, and to identify species-specific chromosome markers that can add new comparative data about Mugilidae karyotype evolution. The karyotype of M. hospes from Ecuador is composed of 48 acrocentric chromosomes and shows two active nucleolar organizer regions (NORs). In situ hybridization, using different types of repetitive sequences (rDNAs, U1 snDNA, telomeric repeats) as probes, identified species-specific chromosome markers that have been compared with those of other species of the genus Mugil. Cytochrome c oxidase subunit I (COI) sequence analysis shows only 92-93% similarity with sequences previously deposited under this species name in GenBank, all of which were from the Atlantic Ocean. Phylogenetic reconstructions indicate the presence of three well-supported hospe mullet lineages whose molecular divergence is compatible with the presence of distinct species. Indeed, the first lineage includes samples from Ecuador, whereas the other two lineages include the Atlantic samples and correspond to M. brevirostris from Brazil and Mugil sp. R from Belize/Venezuela. Results here provided reiterate the pivotal importance of an integrative molecular and cytogenetic approach in the reconstruction of the relationships within Mugilidae.

Cryptic Caribbean species of Scorpaena (Actinopterygii: Scorpaeniformes) suggested by cytogenetic and molecular data

Cytogenetic and molecular analyses enabled identification of two cytotypes among individuals of the spotted scorpion fish Scorpaena plumieri from Margarita Island, Venezuela. Cytotype 1 was characterized by 48 subtelo-acrocentric chromosomes and fundamental number (number of chromosome arms; FN) equalled 48, while cytotype 2 was characterized by two metacentric and 46 subtelo-acrocentric chromosomes and FN was 50. These cytotypes also differed in the location of the ribosomal gene clusters and in the distribution of the constitutive heterochromatin. Moreover, fish from the cytotypes 1 and 2 were found to belong to distinct mitochondrial lineages. The presence of two S. plumieri cytotypes from two lineages separated by high genetic distance suggests that they correspond to sympatric cryptic species.

Two-Color Radiation Generated in a Seeded Free-Electron Laser with Two Electron Beams

We present the experimental evidence of the generation of coherent and statistically stable two-color free-electron laser radiation obtained by seeding an electron beam double peaked in energy with a laser pulse single spiked in frequency. The radiation presents two neat spectral lines, with time delay, frequency separation, and relative intensity that can be accurately controlled. The analysis of the emitted radiation shows a temporal coherence and a shot-to-shot regularity in frequency significantly enhanced with respect to the self-amplified spontaneous emission.

Observation of time-domain modulation of free-electron-laser pulses by multipeaked electron-energy spectrum

We present the experimental demonstration of a new scheme for the generation of ultrashort pulse trains based on free-electron-laser (FEL) emission from a multipeaked electron energy distribution. Two electron beamlets with energy difference larger than the FEL parameter ρ have been generated by illuminating the cathode with two ps-spaced laser pulses, followed by a rotation of the longitudinal phase space by velocity bunching in the linac. The resulting self-amplified spontaneous emission FEL radiation, measured through frequency-resolved optical gating diagnostics, reveals a double-peaked spectrum and a temporally modulated pulse structure.

Cytogenetic analysis of a self-fertilizing fish, Rivulus marmoratus: remarkable chromosomal constancy over a vast geographic range

The aplocheiloid killifish Rivulus marmoratus is the only known self-fertilizing hermaphroditic vertebrate. Most natural populations consist almost entirely of hermaphrodites and comprise arrays of homozygous clones. However, in almost all populations thus far studied, clonal variation, as detected with molecular techniques, is very high. A karyological survey was carried out on specimens from Brazil, the Bahamas, Belize, and Florida (4 locales) by C-banding, silver staining, and fluorescent staining. The chromosome complement of R. marmoratus is surprisingly uniform over its vast geographic range, in terms of both chromosome number and morphology, heterochromatin distribution and composition, and nucleolar organizer region (NOR) distribution. The short arms of chromosome pair 15, where NORs are located, showed the only variation detected in this study: those of pattern A were consistently shorter than those of pattern B; moreover, the latter show positive heteropycnosis with Giemsa staining. The present data demonstrate that chromosomal variation is not a significant part of the clonal divergence in this species, even though its breeding system, by forming homozygotes for new rearrangements almost immediately, should make that variation easier to detect. The high chromosomal homogeneity is discussed in the light of the peculiar natural history of the species.

Investigating factors associated with adherence behaviour in patients with chronic myeloid leukemia: an observational patient-centered outcome study

Background:

Optimal adherence to imatinib therapy is of paramount importance to maximise treatment effectiveness in patients with chronic myeloid leukaemia (CML). The main objective of this study was to investigate patient-reported personal factors associated with adherence behaviour.

Methods:

Analysis was conducted on 413 CML patients receiving long-term therapy with imatinib. Adherence behaviour was measured with the Morisky Medication Adherence Scale and personal factors investigated included: quality of life, perceived social support, fatigue, symptom burden, psychological wellbeing and desire for additional information. Key socio-demographic and treatment-related factors were also taken into account. Univariate and multivariate logistic regression analyses were used to investigate factors associated with optimal adherence to therapy.

Results:

In all, 53% of patients reported an optimal adherence behaviour. The final multivariate model retained the following variables as independent predictors of optimal adherence to therapy: desire for more information (ref. no), odds ratio (OR)=0.43 (95% confidence interval (CI), 0.29–0.66; P<0.001), social support (higher score representing greater support), OR=1.29 (95% CI, 1.11–1.49; P<0.001) and concomitant drug burden (ref. no), OR=1.82 (95% CI, 1.18–2.80; P=0.006).

Conclusion:

This study suggests that a higher level of social support, satisfaction with information received and concomitant drug burden are the main factors associated with greater adherence to long-term imatinib therapy.

Self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering

We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

Experimental demonstration of emittance compensation with velocity bunching

In this Letter we report the first experiments aimed at the simultaneous demonstration of the emittance compensation process and velocity bunching in a high brightness electron source, the SPARC photoinjector in INFN-LNF. While a maximum compression ratio up to a factor 14 has been observed, in a particular case of interest a compression factor of 3, yielding a slice current of 120 A with less than 2 microm slice emittance, has been measured. This technique may be crucial in achieving high brightness beams in photoinjectors aiming at optimized performance of short wavelength single-pass free electron lasers or other advanced applications in laser-plasma accelerators.

Analysis methodology of movable emittance-meter measurements for low energy electron beams

The design of photoinjectors for modern free electron laser linac relies heavily on particular beam behavior in the few meters after the gun. To experimentally characterize it a movable emittance meter was proposed and built [L. Catani et al., Rev. Sci. Instrum. 77, 093301 (2006)] based on the beam slicing technique. This paper addresses all the aspects of analysis of the data acquired with the emittance meter and common to any slit based emittance measurement for low energy beams.

Direct measurement of the double emittance minimum in the beam dynamics of the sparc high-brightness photoinjector

In this Letter we report the first experimental observation of the double emittance minimum effect in the beam dynamics of high-brightness electron beam generation by photoinjectors; this effect, as predicted by the theory, is crucial in achieving minimum emittance in photoinjectors aiming at producing electron beams for short wavelength single-pass free electron lasers. The experiment described in this Letter was performed at the SPARC photoinjector site, during the first stage of commissioning of the SPARC project. The experiment was made possible by a newly conceived device, called an emittance meter, which allows a detailed and unprecedented study of the emittance compensation process as the beam propagates along the beam pipe.

Comparative molecular cytogenetic analysis of two congeneric species, Mugil curema and M. liza (Pisces, Mugiliformes), characterized by significant karyotype diversity

Two congeneric mullet species, Mugil liza and M. curema, respectively with an all-uniarmed and an all-biarmed karyotype, were cytogenetically studied by base-specific fluorochrome staining and FISH-mapping of 45S and 5S ribosomal RNA genes (rDNA) and the (TTAGGG)(n) telomeric repeats. Whereas 45S rDNA sites might be homeologus in the two species, 5S rDNA sites are not, as they are localized on chromosome arms of different size. In both species, the (TTAGGG)(n) telomeric probe hybridized to natural telomeres and was found scattered along the NORs. In metacentric chromosomes of M. curema, no pericentromeric signals of the telomeric probe were detected. Data are discussed in relation to the karyotype evolution in Mugilidae and to the mechanisms and the evolutionary implications of Robertsonian rearrangements in M. curema.

The selection of patients for breast reduction: should health commissions have a say?

Selective or restrictive access policies operate for breast reduction, despite proven benefits. The rationale for these policies, in particular the requirement of psychiatric assessment prior to a plastic surgical consultation, as an aid to patient selection by the health commission, was examined in 57 general practice referrals to a plastic surgical unit. In 22 cases, these policies deterred the patient or GP from pursuing the referral further. Sixteen cases were funded by the health commission directly, 16 patients required psychiatric or orthopaedic referrals, and three patients were refused funding outright. The decision to fund, reject or refer to a non-plastic-surgical specialist was not statistically related to the patients' symptoms. Non-plastic-surgical assessment resulted in referral for a plastic surgical opinion in 15 of 16 patients. We conclude that these selective policies are unsatisfactory, since patient management is not related to symptoms and the use of non-plastic-surgical opinions by the health commission as an aid to rationing is of little benefit.

Cytogenetic analysis of Liza ramada (Pisces, Perciformes) by different staining techniques and fluorescent in situ hybridization

A cytogenetic investigation was carried out on specimens of Liza ramada, a mugilid species common in the Mediterranean sea. The analysis of chromosomes was performed through Ag-staining, C-banding, chromomycin A3 and DAPI staining, and fluorescent in situ hybridization with ribosomal genes. The results obtained are discussed with respect to cytotaxonomic implications and to the features of NORs.

Interleukins 2 and 12 activate natural killer cytolytic responses of peripheral blood mononuclear cells from patients with head and neck squamous cell carcinoma

OBJECTIVES

To examine the capacity of interleukin-2 (IL-2) and interleukin-12 (IL-12) to modulate the cytolytic activity of peripheral blood mononuclear cells against squamous cell carcinoma, and to determine whether peripheral blood mononuclear cells from healthy donors respond differently to IL-12 than do peripheral blood mononuclear cells from patients with head and neck squamous cell carcinoma.

DESIGN

Case-comparison study of a consecutive sample of patients with head and neck squamous cell carcinoma who were scheduled to undergo surgical excision.

PARTICIPANTS

The study included 10 patients with stage III or IV carcinoma matched with 10 volunteer blood donors.

INTERVENTION

Isolated peripheral blood mononuclear cells from patients and volunteers were treated with IL-2, 10 U/mL and 100 U/mL; IL-12, 1 U/mL or 10 U/mL; or a combination of IL-2 and IL-12.

RESULTS

The combination of IL-2 and IL-12 consistently produced the greatest activation cytolysis than either cytokine alone at all concentrations tested. This increased activity against a squamous cell carcinoma cell line was seen in lymphocytes from volunteers and patients.

CONCLUSION

Our findings suggest a new treatment regimen for the patient with head and neck cancer that uses immunomodulation with a combination of cytokines.

Fanconi anemia in brothers initially diagnosed with VACTERL association with hydrocephalus, and subsequently with Baller-Gerold syndrome

Two brothers with presumed Baller-Gerold syndrome, one of whom was previously diagnosed with the association of vertebral, cardiac, renal, limb anomalies, anal atresia, tracheo-esophageal fistula (VACTERL) association with hydrocephalus, were evaluated for chromosome breakage because of severe thrombo cytopenia in one of them. Spontaneous and clastogen-induced breakage was markedly increased in both patients as compared to control individuals. Clinical manifestations and chromosome breakage, consistent with Fanconi anemia, in patients with a prior diagnosis of either Baller-Gerold syndrome, reported earlier in one other patient [Farrell et al., 1994: Am J Med Genet 50:98-99], or with VACTERL association with hydrocephalus, recently reported in 3 patients [Toriello et al., 1991: Proc Greenwood Genet Center 11:142; Porteus et al., 1992: Am J Med Genet 43:1032-1034], underline the clinical heterogeneity of Fanconi anemia and raise the question of whether these syndromes are distinct disorders or phenotypic variations of the same disease.

Plain film evaluation of bone grafting for nonunited scaphoid fractures

OBJECTIVE

To determine how the appearance of fracture line bridging and graft incorporation changed on sequential plain films obtained during the healing of successful grafts for scaphoid nonunion.

DESIGN

We identified 50 patients who had healed Russe bone grafts for nonunited scaphoid fractures. These patients had 214 sets of wrist radiographs obtained 1-36 months after surgery. Each set of radiographs was reviewed in random order by two observers who were blinded as to the patient's name and the time interval since surgery. Closure of the fracture line and the presence of a linear lucency in each of six zones surrounding the graft were assessed using a three-point grading scale.

PATIENTS

Forty-six men and four women were included in the study. Their mean age was 30 years with a range from 21-43 years.

RESULTS AND CONCLUSIONS

With increasing time after surgery, there was progressive fracture line closing and disappearance of linear lucencies at the interfaces between the scaphoid and the graft. However, a 20% of the patients had a well-defined lucency in at least one of the six zones around the graft on their last film. Even 1 year after surgery, the fracture line showed no bridging on the radial side in 22% of patients and on the ulnar side in 11%. We conclude that after grafting, most scaphoid nonunions show progressive fracture line closure and graft incorporation. However, the fracture line may not completely close and lucencies may persist in several zones around the graft for more than 1 year. These radiographic appearances should be recognized as part of the normal spectrum of healing.

Lysis of neuroblastoma cell lines by human natural killer cells activated by interleukin-2 and interleukin-12

Neuroblastoma is the most common extracranial, solid tumor in children. Despite intensive chemotherapy and bone marrow transplantation, the 5-year projected survival rate is 20% to 25%. In vitro studies have shown enhanced natural killer cell (NK) lysis of tumor cells after exposure of NK cells to interleukin-2 (IL-2). In vivo studies have demonstrated similar immunologic effects but have also revealed severe toxicities associated with the use of IL-2. IL-12 is a newly described cytokine that has several properties, including the ability to act synergistically with IL-2 in generating lymphokine-activated killer cells (LAK) against known tumor targets. We investigated the role of IL-12 in the generation of peripheral blood mononuclear cell (PBMC) lysis of neuroblastoma cell lines. PBMC were activated with IL-12 alone and in combination with IL-2. Whereas IL-12 alone produced only modest enhancement of NK cell cytotoxicity, the combination of IL-2 and IL-12 was most effective in activating NK cell lysis of neuroblastoma cell lines. Further, we showed that large granular lymphocytes were the effector cells involved in target cell lysis. Finally, the CD18 molecule was shown to be critical in the lysis of neuroblastoma cells by activated PBMC.

Upper inferior vena caval anastomotic stenosis in liver transplant recipients: Doppler US diagnosis

Ultrasound (US) is routinely used as a screening tool for liver transplant dysfunction. Its use in the detection of significant vascular complications of liver transplantation such as thrombosis or stenosis of the hepatic artery and portal vein is well recognized. Its role in the detection of anastomotic stenosis of the inferior vena cava (IVC) has not been defined. The authors present US findings in five patients with such stenosis. The gray-scale and Doppler findings in all cases consisted of loss of normal hepatic vein and IVC periodicity. Some studies also showed distention of the hepatic veins and IVC and a high-velocity jet at the anastomosis, and in one case the stenosis was visualized with color Doppler US. While there are other causes of absent periodicity in the hepatic veins, this finding in the appropriate clinical setting may be a sensitive indicator of upper IVC anastomotic stenosis.

Cytogenetics of bisexual/unisexual species of Poecilia. V. Unisexual poeciliids with anomalous karyotypes from northeastern Mexico

Unisexual poeciliid fishes collected from two localities in the Soto la Marina drainage have been analyzed. Unisexual diploid and triploid specimens with anomalous karyotypes were found among karyotypically normal specimens. Chromosomal data are discussed in light of the origin of clonal diversity in unisexual/bisexual breeding complexes and with regard to the role of triploids in these breeding complexes.

Cytogenetics of bisexual/unisexual species of Poecilia. II. Analysis of heterochromatin and nucleolar organizer regions in Poecilia mexicana mexicana by C-banding and DAPI, quinacrine, chromomycin A3, and silver staining

Chromosomes of Poecilia mexicana mexicana, one of the bisexual species involved in the hybrid origin of the unisexual teleost fish species P. formosa, were analyzed by several staining techniques. Sex-specific, differential heterochromatin, found in other congeneric species, was not observed in P. m. mexicana. Nucleolar organizer regions were polymorphic among individual specimens within a given population sample. A single specimen exhibiting intraindividual variability of chromosome pair 1 and a specimen with a triploid karyotype are also described.

Cytogenetics of bisexual/unisexual species of Poecilia. II. Analysis of heterochromatin and nucleolar organizer regions in Poecilia mexicana mexicana by C-banding and DAPI, quinacrine, chromomycin A3, and silver staining

Chromosomes of Poecilia mexicana mexicana, one of the bisexual species involved in the hybrid origin of the unisexual teleost fish species P. formosa, were analyzed by several staining techniques. Sex-specific, differential heterochromatin, found in other congeneric species, was not observed in P. m. mexicana. Nucleolar organizer regions were polymorphic among individual specimens within a given population sample. A single specimen exhibiting intraindividual variability of chromosome pair 1 and a specimen with a triploid karyotype are also described.

Cytogenetics of bisexual/unisexual species of Poecilia. III. The karyotype of Poecilia formosa, a gynogenetic species of hybrid origin

Chromosomes of the Amazon molly, Poecilia formosa, a unisexual species of hybrid origin, were investigated by C-banding, silver staining, and fluorescent staining with DAPI, quinacrine dihydrochloride, and chromomycin A3. Analysis of heterochromatin distribution indicates that chromosomes similar to the W chromosome of P. latipinna are not present in the unisexual species. Therefore, morphologically differentiated sex chromosomes do not form the basis of the unisexuality in P. formosa. The number and location of nucleolar organizer regions vary in P. formosa and do not correlate well with those of the parental species.

[Effects of aflatoxins B1 on glucose-6-phosphatase activity in kidney and liver of rats (Rattus rattus norvegicus)]

The authors observed the influence of the B1 aflatoxin over rat liver and kidneys glucose-6-phosphatase activity. Animals aged 30 and 60 days received B1 aflatoxin in oil, 1 mcg/g and 5 mcg/g of body weight. The parameters were observed 6, 24 and 48 hours after the micotoxin administration. There was significant decrease of glucemia in the 30 days animals. In the 60 days animals the results suggested possible increase in the liver glucose-6-phosphatase and marked decrease in glycogen.

[Aminoaciduria screening in newborn infants using, comparatively, chromatographic and colorimetric methods]

The authors showed that the colorimetric methods used to effect aminoacidopathies screening are inadequate and unspecific. The thin layer chromatography was chosen to effect such screening and the authors showed the incidence in newborns of some aminoacid metabolism abnormalities.