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Terahertz (THz) radiation has been of increasing interest in the last decades, for security, manufacturing, quality control, medical and security imaging applications. The field requires more efficient and affordable sources and nonlinear upconversion schemes point in this direction. KTiOPO, (KTP) is a well-established material for nonlinear optical applications in the visible and near-IR region thanks to its large transparency, high nonlinear coefficient and damage threshold. Its reasonably low absorption [1, 2] and strong polariton resonances [1] show promise for efficient IR to THz upconversion and Wu et al. [2] recently demonstrated its superiority to LiNbO3 and LiTaO3 in a back to back experiment. However, the complex refractive index needs to be measured before further power scaling is realistic., QC 20200623

Contains fulltext : 138014.pdf (publisher's version ) (Closed access), AIM: External validation and comparison of the diagnostic accuracy of two predictive tools, the emergency department triad and the clinical scoring tool in diagnosing acute diverticulitis. METHODS: Two derivation datasets were used crosswise for external validation. In addition, both tools were validated in a third independent cohort. Predictive values were reassessed and the Area Under the Curve expressed discriminatory capacity. Performance was compared by calculating positive predictive values of the emergency department triad in the validation cohorts and with a cut-off analysis for the clinical scoring tool at a positive predictive value of 90%. RESULTS: Predictive value of the emergency department triad was comparable to the clinical scoring tool. The positive predictive value of the emergency department triad (97%) decreased in the clinical scoring tool cohort (81%) and was excellent in the independent cohort (100%), identifying 24%, 20% and 14% of the patients. A smaller proportion of patients with diverticulitis could be identified with the clinical scoring tool (6%, 19% and 9%). CONCLUSION: The emergency department triad as well as the clinical scoring tool have significant predictive value in external cohorts of patients suspected of diverticulitis. These tools can be used to select patients in whom additional imaging to diagnose acute diverticulitis may be omitted.

Background: The aim of this study was to elucidate the natural history of appendicitis. Methods: Data was collected prospectively from consecutive patients admitted to hospital for acute abdominal pain. The degree of appendiceal inflammation in relation to preoperative duration of pain was analysed. Results: The study comprised 253 patients operated on for acute appendicitis that could recall the onset of abdominal pain. There was a longer duration of pre-hospital pain in patients, irrespective of age, with perforated appendicitis compared to patients with phlegmonous or gangrenous appendicitis (p < 0.001). In the multivariate analysis, patient age and preoperative duration of pain were independent risk factors for perforation. Conclusion: Patient delay in presentation is the predominant factor determining the incidence of complicated appendicitis, and this delay is not influenced by age or gender.

OBJECTIVE: To describe the clinical presentation of acute diverticulitis in an emergency department and to characterize the natural history of diverticulitis in the short perspective. Comparisons are made with an important differential diagnosis, nonspecific abdominal pain (NSAP). METHOD: Patients admitted to our hospital with abdominal pain of up to 7 days' duration were registered prospectively using a detailed schedule for history, symptoms and signs, from 1 February 1997 to 1 June 2000. Of 3349 patients initially included, 3073 (92%) were eligible for follow up after 1-3 years. RESULTS: Acute diverticulitis was the final diagnosis in 145 patients and NSAP in 1142 patients. The incidence of hospitalized patients with diverticulitis was 47 per year and 100 000 population, with a mean hospital stay of 3.3 days. Patients with diverticulitis, more frequently than NSAP, had a longer history and laboratory signs of inflammatory activity. Isolated left abdominal tenderness was more common in diverticulitis, whereas isolated right abdominal tenderness was more common in NSAP. Duration of symptoms on arrival was independent of age and was not correlated to C-reactive protein, leucocytes or body temperature. Sensitivity of diverticulitis as primary diagnosis was 64% and specificity 97%. Corresponding figures for NSAP were 43% and 90% respectively. Age and gender did not influence diagnostic accuracy or risk of surgery. CONCLUSION: Diverticulitis differs significantly from NSAP in clinical presentation and laboratory parameters. Sensitivity of primary diagnosis for diverticulitis and NSAP was low.

BACKGROUND: Diagnosis of acute abdominal pain in older persons is a challenge, with the age-related increase in concurrent diseases. In most western countries the number of elderly people is constantly rising, which means that an increasing proportion of patients admitted for abdominal pain at the emergency department are elderly. OBJECTIVE: To characterize differences in clinical presentation and diagnostic accuracy between younger and more elderly patients with acute abdominal pain. METHODS: Patients admitted to Mora Hospital with abdominal pain of up to seven days' duration were registered according to a detailed schedule. From 1st February 1997 to 1st June 2000, 557 patients aged 65-79 years and 274 patients aged > or = 80 years were registered. Patients aged 20-64 years (n = 1,458) served as a control group. RESULTS: A specific diagnosis, i.e. other than 'nonspecific abdominal pain', was established in 76 and 78% of the patients aged 65-79 and > or = 80 years respectively, and in 64% of those aged 20-64 (p < 0.001). Pain duration before admission increased with age (p < 0.003), as did frequency and duration of hospitalization (p < 0.0001). Hospital stay increased from 170 days per 100 emergency admissions in the control group to 320 and 458 days in the younger and older study groups, respectively. At the emergency department, older patients were more often misdiagnosed than control patients (52 vs. 45%; p = 0.002). At discharge the diagnosis was more accurate in the control group (86 vs. 77%; p < 0.0001). Hospital mortality was higher among older patients (23/831 vs. 2/1,458; p < 0.001). The admission-to-surgery interval was increased (1.8 vs. 0.9 days, p < 0.0001) in patients > or = 65 years. Rebound tenderness (p < 0.0001), local rigidity (p = 0.003) and rectal tenderness (p = 0.004) were less common in the older than in the control patients with peritonitis. In patients > or = 65 years, C-reactive protein did not differ betwe

BACKGROUND: The aim of this study was to characterize patients seeking medical advice for acute abdominal pain who were later diagnosed with an intra-abdominal malignancy. PATIENTS AND METHODS: Patients with acute abdominal pain were registered between 1997 and 2000, employing a detailed schedule comprising 111 parameters. The diagnoses (n=2395 patients) were re-evaluated one year later. RESULTS: A total of 66 patients (2.8%) were found to have an intra-abdominal malignancy at follow-up, of whom 37 cases had been undetected at discharge. Malignancy of the liver, biliary tract and pancreas constituted 30% and colorectal cancer 32% of the tumours undetected at discharge. Constipation, intestinal obstruction and non-specific abdominal pain (NSAP) were the most common preliminary diagnoses in patients among whom abdominal malignancy was later detected. CONCLUSION: Except for age and pain duration, the history and clinical investigation provide few clues to suggest an abdominal malignancy in patients with acute abdominal pain. NSAP, of unknown or known etiology, including constipation, should be suspected as a possible sign of abdominal malignancy in all patients over 50 years of age.

SCOPUS: ar.j, info:eu-repo/semantics/published

SCOPUS: ar.j, info:eu-repo/semantics/published

NR 20160226