FLASH free electron laser pump-probe laser concept based on spectral broadening of high-power ytterbium picosecond systems in multi-pass cells.

Within the FLASH2020+ upgrade, the pump-probe laser capabilities of the extreme ultraviolet and soft x-ray free-electron laser (XFEL) FLASH in Hamburg will be extended. In particular, providing wavelength tunability, shorter pulse durations, and reduced arrival time jitter will increase the scientific opportunities and the time resolution for the XFEL-optical laser pump-probe experiments. We present here a novel concept for the pump-probe laser at FLASH that is based on the post-compression of picosecond pulses emitted from high-power Ytterbium:YAG slab amplifiers. Flexible reduction of the pulse duration is facilitated by spectral broadening in pressure-tunable multi-pass cells. As an application, we show the pumping of a commercial optical parametric amplifier with 150 fs post-compressed pulses. By means of an additional difference frequency generation stage, tunable spectral coverage from 1.3 to 16 µm is reached with multi-µJ, sub-150 fs pulses. Finally, a modular reconfiguration approach to the optical setups close to the free-electron laser instruments is implemented. This enables fast installation of the nonlinear frequency converters at the end stations for user operation and flexibility between different instruments in the two experimental halls.

Highly efficient generation of narrowband terahertz radiation driven by a two-spectral-line laser in PPLN.

We demonstrate record ∼0.9% efficiencies for optical conversion to narrowband (<1% relative bandwidth) terahertz (THz) radiation by strongly cascaded difference frequency generation. These results are achieved using a novel, to the best of our knowledge, laser source, customized for high efficiencies, with two narrow spectral lines of variable separation and pulse duration (≥250 ps). THz radiation generation in 5% MgO-doped periodically poled lithium niobate (PPLN) crystals of varying poling period was explored at cryogenic and room temperature operation as well as with different crystal lengths. This work addresses an increasing demand for high-field THz radiation pulses which has, up to now, been largely limited by low optical-to-THz radiation conversion efficiencies.

Cascaded interactions mediated by terahertz radiation.

We investigate a regime of parametric amplification in which the pump and signal waves are spectrally separated by only a few hundreds of GHz frequency - therefore resulting in a sub-THz frequency idler wave. Operating in this regime we find an optical parametric amplifier (OPA) behavior which is highly dissimilar to conventional OPAs. In this regime, we observe multiple three-wave mixing processes occurring simultaneously which results in spectral cascading around the pump and signal wave. Via numerical simulations, we elucidate the processes at work and show that cascaded optical parametric amplification offers a pathway toward THz-wave generation beyond the Manly-Rowe limit and toward the generation of high-energy, sparse frequency-combs.

AXSIS: Exploring the frontiers in attosecond X-ray science, imaging and spectroscopy.

X-ray crystallography is one of the main methods to determine atomic-resolution 3D images of the whole spectrum of molecules ranging from small inorganic clusters to large protein complexes consisting of hundred-thousands of atoms that constitute the macromolecular machinery of life. Life is not static, and unravelling the structure and dynamics of the most important reactions in chemistry and biology is essential to uncover their mechanism. Many of these reactions, including photosynthesis which drives our biosphere, are light induced and occur on ultrafast timescales. These have been studied with high time resolution primarily by optical spectroscopy, enabled by ultrafast laser technology, but they reduce the vast complexity of the process to a few reaction coordinates. In the AXSIS project at CFEL in Hamburg, funded by the European Research Council, we develop the new method of attosecond serial X-ray crystallography and spectroscopy, to give a full description of ultrafast processes atomically resolved in real space and on the electronic energy landscape, from co-measurement of X-ray and optical spectra, and X-ray diffraction. This technique will revolutionize our understanding of structure and function at the atomic and molecular level and thereby unravel fundamental processes in chemistry and biology like energy conversion processes. For that purpose, we develop a compact, fully coherent, THz-driven atto-second X-ray source based on coherent inverse Compton scattering off a free-electron crystal, to outrun radiation damage effects due to the necessary high X-ray irradiance required to acquire diffraction signals. This highly synergistic project starts from a completely clean slate rather than conforming to the specifications of a large free-electron laser (FEL) user facility, to optimize the entire instrumentation towards fundamental measurements of the mechanism of light absorption and excitation energy transfer. A multidisciplinary team formed by laser-, accelerator,- X-ray scientists as well as spectroscopists and biochemists optimizes X-ray pulse parameters, in tandem with sample delivery, crystal size, and advanced X-ray detectors. Ultimately, the new capability, attosecond serial X-ray crystallography and spectroscopy, will be applied to one of the most important problems in structural biology, which is to elucidate the dynamics of light reactions, electron transfer and protein structure in photosynthesis.

Energy scaling of a carbon nanotube saturable absorber mode-locked femtosecond bulk laser.

We report successful energy scaling of a room-temperature femtosecond Cr4+: forsterite laser by using a single-walled carbon nanotube saturable absorber (SWCNT-SA). By incorporating a q-preserving multipass cavity, a repetition rate of 4.51 MHz was realized, and the oscillator produced 121 fs, 10 nJ pulses at 1247 nm, with an average output power of 46 mW. To the best of our knowledge, the peak power of 84 kW is the highest generated to date from a SWCNT-SA mode-locked oscillator. Furthermore, energy scaling of a femtosecond multipass-cavity laser, mode-locked using a SWCNT-SA, is demonstrated for the first time.

Prolonged Raman lasing in size-stabilized salt-water microdroplets on a superhydrophobic surface.

We demonstrate prolonged Raman lasing from individual salt-water microdroplets with 10-20 microm diameters located on a superhydrophobic surface. The mechanism is based on the absorption heating of a 1064 nm cw IR laser and the resonant heating of a 532 nm pulsed, pump laser. A clear hysteresis is observed in the lasing intensity as the droplet size is photothermally tuned by the IR laser, indicating a self-stabilization mechanism due to the resonant absorption of the pump laser. Using this mechanism, Raman lasing near 650 nm is sustained for up to 25 min, approximately 1000 times longer than lasing durations reported in previous studies.

A case of unilateral mydriasis secondary to septoplasty under local anaesthesia.

Septoplasty is a procedure performed to correct deformities of the nasal septum. Serious complications associated with septoplasty include orbital complications. Here, we present a 26-year-old male patient who developed unilateral mydriasis while undergoing septoplasty under local anaesthesia. The mydriasis resolved spontaneously in an hour without any sequel. In the present study, we emphasise the orbital complications that can be observed during septoplasty.

A giant paediatric mandibular aneurysmal bone cyst and reconstruction with bilateral iliac bone graft.

A giant paediatric mandibular aneurysmal bone cyst and reconstruction with bilateral iliac bone graft. Aneurysmal bone cyst (ABC) is an unusual, non-neoplastic, expansile lesion of the bone. ABC is not a true cyst and it is characterised by the replacement of bone by fibro-osseous tissue containing blood-filled sinusoidal or cavernous spaces. The expanding mass often disrupts the normal bony architecture, with erosion of the cortex. Surgical treatment consists of complete excision or curettage. In this report, we present a 5-year-old girl with a huge aneurysmal bone cyst in the corpus of the mandible, which was reconstructed with bone graft taken from bilateral anterior iliac crests.

A case of concha pyocele (concha bullosa mucocele) mimicking intranasal mass.

Concha bullosa is the most common anatomic variant of the middle turbinate that usually remains asymptomatic. If the mucosal lining of pneumatized middle turbinate becomes inflamed, symptoms such as nasal obstruction, post-nasal discharge, snoring, headache, and fever occur. We report a case of concha pyocele (concha bullosa mucocele) in a 19-year-old girl. Computed tomography identified a right intranasal mass expanding towards the medial wall of the right maxillary sinus, nasal septum and right ethmoidal cells. The concha pyocele caused obstruction of the ostiomeatal complex, leading to right maxillary, ethmoid and sfenoid sinusitis. The patient was endoscopically treated under local anaesthesia. Histological examination of the mass revealed an active chronic inflammation caused by a foreign body.

Turkish dentists' knowledge of head and neck cancer therapy-related complications: implications for the future.

UNLABELLED: The objective was to determine the level of knowledge about the orodental complications and their prevention/management in head and neck cancer therapy. MATERIALS AND METHODS: A 15-item questionnaire which was obtained from National Institute of Dental and Craniofacial Research that contained information about the orodental complications of the cancer therapy and the dentists' role to provide their treatment protocols. The pollsters visited 380 respondents, and the replies were analysed with stratified and logistic data analyses. Overall correct replies ranged from 14.71% to 99.5%. The participants knew the basic knowledge of the complications of cancer therapy; however, they failed to answer to the questions about the required clinical practices. The gender (P = 0.967), age (P = 0.977) and the duration of practice (P = 0.99) were not significant factors in providing correct replies. The rate of correct replies were not different among the test groups (P = 0.953). As a conclusion, rectification of dental curricula, organization of postgraduation courses, foundation of national councils for stimulation of the healthcare providers to incorporate knowledge into practice, to monitor the continuity of those programmes, and to award the dental practitioners who keep up the recent literature and optimal clinical practice are vital to improve the life quality of cancer patients.

Facial subcutaneous calcinosis and mandibular resorption in systemic sclerosis: a case report.

Systemic sclerosis (SSc) is an autoimmune disease characterized by widespread fibrosis of subcutaneous connective tissue, causing serious complications with the involvement of other systems. Tight, firm skin is the main characteristic of SSc, causing extrinsic pressure and the obliteration of the vessels. This then leads to ischaemia and destruction of the underlying bone. This mechanism may also lead to bone resorption of the mandibular body as it affects other bones of the skeleton. To date, only two cases of reported calcinosis in the facial area have been observed. In this report, a rare case of SSc with both subcutaneous calcinosis and mandibular bone resorption is presented. The role of dental practitioners in the diagnosis of the disease with respect to the orofacial symptoms is also discussed.

Papillary thyroid carcinoma presenting as a giant cervical mass: a case report.

Papillary thyroid carcinoma (PTC) is a relatively uncommon malignancy. The prognosis is generally good and the mortality rate is low. PTC is more common in younger patients; incidence is two to three times higher in women and in individuals with radiation exposure to the neck. We report on a 75-year-old woman with PTC admitted to our clinic for a giant mass in the neck dating back ten years. A hyperintense huge cystic lesion and hypo-intense central solid component were seen on T1- and T2-weighted magnetic resonance imaging. No distant metastasis was present. The PTC was treated surgically and radioiodine (131I) treatment was applied postoperatively. No recurrence was observed one year later.

Maxillary and temporal fibrous dysplasia: three cases.

PROBLEMS/OBJECTIVES: Fibrous dysplasia (FD) is a benign, expansile lesion of bone with slow progression and unknown origin. The purpose of this report is to make physicians aware of the symptoms, methods for differential diagnosis, and treatment options. METHODOLOGY: Three cases of monostotic FD are presented; two involving the maxillary sinus, and one in temporal bone. CT scans are the definitive diagnostic and follow-up method. Surgical approaches to alleviate the symptoms, including facial deformity, are described. RESULTS: FD went undiagnosed for three years in these patients. All three patients were relieved of the symptoms by limited surgery, and remained asymptomatic for up to two years after the surgery, with no signs of recurrence. CONCLUSIONS: Practitioners should be alert to the possibility of FD, particularly if patients develop narrowing of the ear canal, or progressive postauricular or maxillofacial enlargement. Minimal surgery to alleviate the symptoms is the treatment of choice.

Hairy tongue: a case report.

Hairy tongue or black hairy tongue is a benign condition characterized by hypertrophy of the filiform papillae that give the dorsum of the tongue a furry appearance. The color of the elongated papillae varies from yellowish white to brown or black. The etiology is unclear, but the disorder has been associated with numerous predisposing conditions such as heavy smoking, poor oral hygiene, use of topical or systemic antibiotics, systemic corticosteroid therapy, yeast infections, and radiotherapy for head and neck malignancies. A case is presented in which a hairy tongue appeared in a 67-year-old man.

Pneumatization of the concha inferior as a cause of nasal obstruction.

Chronic nasal obstruction is a common disorder. Hypertrophy of the inferior turbinates is responsible for nasal obstruction more frequently than it is commonly thought. A pneumatized inferior turbinate has recently been described as a cause for nasal obstruction and only two cases have been reported until now. Inferior nasal turbinate develops by endochondral ossification of components of the mesethmoid and ectethmoid. The chondral framework of the inferior turbinate consists of a double lamella and two separate ossification centers that develop between the fifth and seventh month of fetal life. The separate ossification centers meet by the eighth fetal month. During ossification, the inferior turbinate detaches from the ectethmoid and becomes an independent bony structure. During that time the epithelium may misinvaginate into double lamellas and such double lamellas formed by the inferior turbinate may become persistent. A patient was referred to our clinic with headaches and nasal obstruction. A CT scan was performed which showed that the right lower concha was pneumatized. The headache of the patient disappeared after partial resection of the lower and middle turbinate.

Head and neck granulocytic sarcoma with acute myeloid leukemia: three rare cases.

We conducted a retrospective review of pathology files and hospital records and identified three unusual presentations of granulocytic sarcoma associated with acute myeloid leukemia (AML) of the head and neck. At least one mass was observed on the skin of all three patients. A 17-year-old boy had masses in each temporal region that were accompanied by bilateral facial paralysis. He was administered chemotherapy and radiotherapy, but he died of infection secondary to a second relapse 29 months after the initial diagnosis. A 17-year-old girl had a tumor in the right parotid area. She received chemotherapy, but she died of infection and bleeding 2 months after the initial diagnosis. A 33-year-old man had numerous tumors widely disseminated over his skin. He received chemotherapy and was in remission 12 months after the initial diagnosis, but he eventually relapsed and died. Granulocytic sarcoma can be localized in unexpected regions, including the head and neck. This tumor is very often misdiagnosed as a malignant lymphoma, which leads to delayed treatment and a poor outcome. Therefore, clinical and histopathologic findings should be evaluated before any diagnosis of malignant lymphoma is pronounced. Immunohistochemical stains should also be performed on patients with suspected granulocytic sarcoma, and aggressive chemotherapy or immunotherapy should be administered. We believe that high-dose chemotherapy can improve survival rates in granulocytic sarcoma associated with AML.

Factors of patient satisfaction/dissatisfaction in a dental faculty outpatient clinic in Turkey.

OBJECTIVES: Being service providers, dental professionals should satisfy their consumers/dental patients. This study investigates satisfaction with dental care among the patients of a dental faculty outpatient clinic of a major university in Izmir, Turkey. METHOD: The study was performed on 1001 patients of whom 674 filled out the questionnaire containing sociodemographic items and open-ended questions to determine the factors of (dis)satisfaction. The open-ended questions were content analyzed, and each patient was scored according to his comments: "complaining: (0)", "both praising and complaining: (1)", "no comment: (2)", and "praising: (3)". Each factor that has an impact on the decision of the study sample was determined by statistical analyses of data, using student t-test, chi-square test, and multiple regression analysis. RESULTS: Most of the patients were highly educated (74.7%), had a high income (48.7%), and were young to middle-aged (73.1%). There was a well-balanced gender representation. The patient sample had sought care mostly for dental caries, periodontal diseases, problems with old restorations, and prosthetic rehabilitation. Of 1,001 patients, 38.6% were satisfied with the dental care they received, 23.8% were both satisfied and dissatisfied, 5% were dissatisfied, and 32.7% failed to comment. No significant differences were observed between the satisfaction/dissatisfaction scores and sociodemographic variables of the patients in the groups (P>0.05). The most important components of satisfaction were found to be "relationship between dentists and patients" (P<0.001), "organized service system" (P<0.001), and "scientific ability of dental personnel" (P<0.001). The most prominent complaints were "long treatment span" (P<0.001), "disorganized service system" (P<0.001), and "slowness of radiographical examination procedures" (P<0.001). CONCLUSIONS: Despite the significant variations among the cultural and ethnic structures of different societies, personal interactions have priority in establishing satisfying dental service.

Clinical value of preoperative intraoral ultrasonography in tonsillectomy.

In this prospective study, 43 chronic tonsillitis patients underwent intraoral ultrasonography preoperatively and the width and thickness of tonsils and tonsillocarotid distances were measured. Positive correlation was obtained in postoperative measurements compared with ultrasonographic measurements of tonsils. The mean tonsillocarotid distances were 8.6 mm in the left and 8.25 mm in the right tonsillar fossa. This study showed that preoperative intraoral ultrasonography was to be help of tonsillectomy operations particularly in surgical anatomical orientation.