Investigation of hollow cylindrical metal terahertz waveguides suitable for cryogenic environments.

The field of terahertz (THz) waveguides continues to grow rapidly, with many being tailored to suit the specific demands of a particular final application. Here, we explore waveguides capable of enabling efficient and accurate power delivery within cryogenic environments (< 4 K). The performance of extruded hollow cylindrical metal waveguides made of un-annealed and annealed copper, as well as stainless steel, have been investigated for bore diameters between 1.75 - 4.6 mm, and at frequencies of 2.0, 2.85 and 3.4 THz, provided by a suitable selection of THz quantum cascade lasers. The annealed copper resulted in the lowest transmission losses, < 3 dB/m for a 4.6 mm diameter waveguide, along with 90° bending losses as low as ~2 dB for a bend radius of 15.9 mm. The observed trends in losses were subsequently analyzed and related to measured inner surface roughness parameters. These results provide a foundation for the development of a wide array of demanding low-temperature THz applications, and enabling the study of fundamental physics.

Hollow metallic waveguides integrated with terahertz quantum cascade lasers.

We present the realization of a compact, monolithically integrated arrangement of terahertz quantum cascade lasers with hollow metallic cylindrical waveguides. By directly mounting a copper pipe to the end facet of a double metal waveguide, it was possible to significantly improve the far field emission from such a sub-wavelength plasmonic mode, while preserving the characteristic performance of the laser. Careful alignment of the quantum cascade laser and the hollow waveguide is required in order to prevent the excitation of higher order/mixed modes as predicted with a high degree of accuracy by a theoretical model. Finally, this approach proved to be a superior method of beam shaping when compared to other in situ arrangements, such as a silicon hyper-hemispherical lens glued to the facet, which are presented.

A multicenter phase II study of induction chemotherapy with FOLFOX-4 and cetuximab followed by radiation and cetuximab in locally advanced oesophageal cancer.

BACKGROUND: Preoperative chemoradiotherapy (CRT) improves the survival of patients with oesophageal cancer when compared with surgery alone. METHODS: We conducted a phase II, multicenter trial of FOLFOX-4 and cetuximab in patients with locally advanced oesophageal cancer (LAEC) followed by daily radiotherapy (180 cGy fractions to 5040 cGy) with concurrent weekly cetuximab. Cytokines levels potentially related to cetuximab efficacy were assessed using multiplex-bead assays and enzyme-linked immunosorbent assay at baseline, at week 8 and at week 17. Primary end point was complete pathological response rate (pCR). RESULTS: In all, 41 patients were enroled. Among 30 patients who underwent surgery, a pCR was observed in 8 patients corresponding to a rate of 27%. The most frequent grade 3/4 toxicity was skin (30%) and neutropenia (30%). The 36-month survival rates were 85 and 52% in patients with pathological CR or PR vs 38 and 33% in patients with SD or PD. CONCLUSIONS: Incorporating cetuximab into a preoperative regimen for LAEC is feasible; no correlation between cytokines changes and patient outcome was observed. Positron emission tomography/computed tomography study even if influenced by the small number of patients appears to be able to predict patients outcome both as early and late metabolic response.

Differential near-field scanning optical microscopy with THz quantum cascade laser sources.

We have realized a differential Near-field Scanning Optical Microscope (NSOM) working with subwavelength resolution in the THz spectral region. The system employs a quantum cascade laser emitting at lambda approximately 105 microm as source, and the method, differently from conventional NSOM, involves diffracting apertures with size comparable to the wavelength. This concept ensures a higher signal-to-noise level at the expense of an additional computational step. In the implementation here reported lambda/10 resolution has been achieved; present limiting factors are investigated through finite difference time domain simulations.

UV second harmonic generation at 266 nm in He+ implanted beta-BaB2O4 optical waveguides.

We report on the second harmonic generation of deep UV light in beta -BaB(2)O(4) (BBO) waveguides pumped by a frequency-doubled continuous-wave Nd:YAG laser. An output power of 0.32 mW at 266 nm has been achieved for an internal pump power of 670 mW. Optical channel waveguides in BBO crystals were produced by He(+) ion implantation, lithographic masking and ion etching. The linear and nonlinear optical properties and the power handling capability of these waveguides are presented.

External amplitude and frequency modulation of a terahertz quantum cascade laser using metamaterial/graphene devices.

Active control of the amplitude and frequency of terahertz sources is an essential prerequisite for exploiting a myriad of terahertz applications in imaging, spectroscopy, and communications. Here we present a optoelectronic, external modulation technique applied to a terahertz quantum cascade laser which holds the promise of addressing a number of important challenges in this research area. A hybrid metamaterial/graphene device is implemented into an external cavity set-up allowing for optoelectronic tuning of feedback into a quantum cascade laser. We demonstrate powerful, all-electronic, control over the amplitude and frequency of the laser output. Full laser switching is performed by electrostatic gating of the metamaterial/graphene device, demonstrating a modulation depth of 100%. External control of the emission spectrum is also achieved, highlighting the flexibility of this feedback method. By taking advantage of the frequency dispersive reflectivity of the metamaterial array, different modes of the QCL output are selectively suppressed using lithographic tuning and single mode operation of the multi-mode laser is enforced. Side mode suppression is electrically modulated from ~6 dB to ~21 dB, demonstrating active, optoelectronic modulation of the laser frequency content between multi-mode and single mode operation.

Hyperuniform disordered terahertz quantum cascade laser.

Laser cavities have been realized in various different photonic systems. One of the forefront research fields regards the investigation of the physics of amplifying random optical media. The random laser is a fascinating concept because, further to the fundamental research investigating light transport into complex media, it allows us to obtain non-conventional spectral distribution and angular beam emission patterns not achievable with conventional approaches. Even more intriguing is the possibility to engineer a priori the optical properties of a disordered distribution in an amplifying medium. We demonstrate here the realization of a terahertz quantum cascade laser in an isotropic hyperuniform disordered distribution exhibiting unique features, such as the presence of a photonic band gap, low threshold current density, unconventional angular emission and optical bistability.

Outbreak of Clostridium difficile diarrhoea in an orthopaedic unit: evidence by phage-typing for cross-infection.

In a three-week period five patients had diarrhoea in an orthopaedic unit. The first case was clinically diagnosed as pseudomembranous colitis but the causative agent was not sought. Of the remaining cases, two were Clostridium difficile positive. The outbreak then apparently ceased, but during the following several days two of seven stool samples taken at random from asymptomatic patients yielded C. difficile. Phage-typing of the isolates showed that all apparently belonged to the same strain.

Aetiologic diagnosis of ischaemic stroke in the emergency department: relevance for triage and clinical management.

Effective strategies for the aetiologic diagnosis in patients with ischaemic stroke can be implemented based on simple clinical criteria and instrumental tests which can be performed in a modern emergency room (ER) within 24 hours from admission. This may bear prognostic and therapeutic relevance for patients with acute stroke. Therefore, in this study we set out to establish the feasibility and accuracy of the aetiologic diagnosis of ischaemic stroke in an ER. A total of 136 consecutive patients (mean age 72+/-10 years, 60 females) with first ever ischaemic stroke admitted during 1996-1997 were evaluated with assessment of clinical features, CT scan, ECG, ultrasonography of the extracranial arteries, transthoracic echocardiography, and, in selected patients, transoesophageal echocardiography. Patients were classified into two major categories defined as stroke of determined origin and stroke of undetermined origin (a stroke with two or more possible causes or with a negative evaluation), according to the TOAST criteria. Ninety-six patients were considered affected by stroke of determined origin (70.5%), (22.7% with large artery atherosclerosis, 19.1% with cardioembolic stroke, 26.4% with lacunar stroke and 1.4% with other aetiology). The remaining 40 patients (29.4%) had stroke of undetermined origin: of these, 13 patients (9.5%) had a totally negative evaluation, 15 patients (12.5%) showed cardioembolism among the two or more possible causes of stroke and seven patients (5.1%) had atherothrombotic or lacunar aetiology. Additional work-up with transoesophageal echocardiography succeeded in demonstrating aortic embolism in five patients (3.6%; i.e. four patients with aortic plaques more than 4 mm in thickness and one patient with ulcerated plaques). In conclusion, the subtype classification system for ischaemic stroke allowed the aetiological diagnosis in 70.5% of patients while in the ER. Stroke of undetermined origin represented one-third of patients in a consecutive population with acute onset neurologic deficit of ischaemic origin. In approximately half of the patients with negative standard evaluation, cardiogenic or aortic arch embolic sources could be identified by transoesophageal echocardiography. Thus, the latter is indicated in patients with stroke of undetermined origin with negative first-line evaluation in order to identify embolic sources in the aortic arch.

Cluster of cases of Salmonella enterica serotype Rissen infection in a general hospital, Italy, 2007.

In 2007, three strains of Salmonella enterica serotype Rissen (S. Rissen) were isolated in the laboratory of diagnostic microbiology of the General Hospital of Prato, Tuscany, Italy, over a 1 month and half interval of time. The first isolate was recovered on January 26 from an outpatient with enteritis. Then, two strains were isolated on February 16 and March 11 respectively, from central venous catheters of patients who were being hospitalized in two departments of the Hospital. An epidemiologically linked cluster of cases of salmonellosis was suspected. The three strains were submitted to single enzyme-amplified fragment length polymorphism (SE-AFLP) and XbaI macrorestriction and pulsed-field gel electrophoresis (PFGE) that yielded undistinguishable profiles. Epidemiological investigations failed to identify a common source of infection within the Hospital. Moreover, the third patient had been exclusively total parenteral nutrition fed since his admission with a stomach cancer diagnosis. The first patient had a community-acquired infection, but the source of her illness was uncertain. Twenty-five further isolates identified in the years 2004-2007 in the same geographical area showed distinctly different PFGE and SE-AFLP patterns. The three patients seemed to represent a cluster of epidemiologically unrelated cases caused by a previously never recognized S. Rissen strain. Rapid subtyping of isolates is essential in the early investigation of potential outbreaks, but synthesis of conventional and molecular epidemiological investigation and availability of surveillance data is often critical to prevent the initiation of time-consuming, expensive and ineffective further investigations and control interventions.

[Study of esophageal motility in diabetic patients using the scintigraphic method]. / Studio della motilità esofagea in pazienti diabetici con metodo scintigrafico.

Oesophagus scintigraphy with 99mTc was used to evaluate oesophageal motility in a group of 23 diabetics without symptoms of autonomic neuropathy (AN). 11 patients were found to have a pathological response to the cardiovascular AN nerve tests. This group of diabetic patients with asymptomatic AN had a high frequency of esophageal dysfunction and a pattern of motor change characterized by uncoordinated movements compared with the group of diabetics without AN and with controls. No correlation between duration of diabetes, insulin dependence, presence of peripheral neuropathy (PN) and motor changes was found. The authors conclude asserting that oesophagus scintigraphy, owing to its sensibility, can lead to an early diagnosis of oesophageal dysfunction in diabetics when symptoms of NA are not yet observed.

[Pyocin typing of 111 strains of Pseudomonas aeruginosa isolated in Tuscany, using the Gillies and Govan method]. / Tipizzazione piocinica secondo Gillies e Govan di 111 stipiti di "Pseudomonas aeruginosa" isolati in Toscana.

Pseudomonas aeruginosa strains from Tuscany have been typed for pyocine production against Govan and Gillies' extended set of indicator strains; results have been expressed following a binary code. Among 111 strains only 6 could not be typed; the remaining 105 strains (94.6%) presented 59 different patterns, 44 of which were represented by one isolate only. The most commonly encountered pattern (n. 8045, corresponding to Govan and Gillies' subtype 1e) was shared by 13 strains. Isolates from outpatients or from the environment tended to a uniform distribution of pyocine patterns; those from two different hospitals tended to group into distinct subtypes.

Transfer of reactivity with in vitro produced transfer factor in rhesus and owl monkeys.

Transfer factors against two heterologous antigens, Herpesvirus saimiri and owl monkey kidney cells, were replicated in vitro in a human lymphoblastoid cell line (LDV/7) and injected into rhesus and owl monkeys. Transfer of immunity was demonstrated by the leukocyte migration inhibition assay. This study suggests that heterologous transfer factor, replicated in vitro, can transfer cellular immunity against membrane antigens in rhesus and owl monkeys.