Electrolyte-gated charge transport in molecularly linked gold nanoparticle films: The transition from a Mott insulator to an exotic metal with strong electron-electron interactions.

Strong electron-electron interactions experienced by electrons as they delocalize are widely believed to play a key role in a range of remarkable phenomena such as high Tc superconductivity, colossal magnetoresistance, and others. Strongly correlated electrons are often described by the Hubbard model, which is the simplest description of a correlated system and captures important gross features of phase diagrams of strongly correlated materials. However, open challenges in this field include experimentally mapping correlated electron phenomena beyond those captured by the Hubbard model, and extending the model accordingly. Here we use electrolyte gating to study a metal-insulator transition (MIT) in a new class of strongly correlated material, namely, nanostructured materials, using 1,4-butanedithiol-linked Au nanoparticle films (NPFs) as an example. Electrolyte gating provides a means for tuning the chemical potential of the materials over a wide range, without significantly modifying film morphology. On the insulating side of the transition, we observe Efros-Shklovskii variable range hopping and a soft Coulomb gap, evidencing the importance of Coulomb barriers. On the metallic side of the transition, we observe signatures of strong disorder mediated electron-electron correlations. Gating films near MIT also reveal a zero-bias conductance peak, which we attribute to a resonance at the Fermi level predicted by the Hubbard and Anderson impurity models when electrons delocalize and experience strong Coulomb electron-electron interactions. This study shows that by enabling large changes in carrier density, electrolyte gating of Au NPFs is a powerful means for tuning through the Hubbard MIT in NPFs. By revealing the range of behaviours that strongly correlated electrons can exhibit, this platform can guide the development of an improved understanding of correlated materials.

Changes in quantity and spectroscopic properties of water-extractable organic matter during soil aquifer treatment.

The aim of this study was to identify qualitative and quantitative changes in the character of water-extractable organic matter (WEOM) in soils as a consequence of soil aquifer treatment (SAT). Soil samples were obtained from a soil-column system with a 2-year operation, and divided into seven layers from top to bottom: CS1 (0-12.5 cm), CS2 (12.5-25 cm), CS3 (25-50 cm), CS4 (50-75 cm), CS5 (75-100 cm), CS6 (100-125 cm) and CS7 (125-150 cm). A sample of the original soil used to pack the columns was also analysed to determine the effects of SAT. Following 2 years of SAT operation, both soil organic carbon and water-extractable organic carbon were shown to accumulate in the top soil layer (0-12.5 cm), and to decrease in soil layers deeper than 12.5 cm. The WEOM in the top soil layer was characterized by low aromaticity index (AI), low emission humification index (HIX) and low fluorescence efficiency index (F(eff)). On the other hand, the WEOM in soil layers deeper than 12.5 cm had increased values of HIX and F(eff), as well as decreased AI values relative to the original soil before SAT. In all soil layers, the percentage of hydrophobic and transphilic fractions decreased, while that of the hydrophilic fraction increased, as a result of SAT. The production of the amide-2 functional groups was observed in the top soil layer. SAT operation also led to the enrichment of hydrocarbon and amide-1 functional groups, as well as the depletion of oxygen-containing functional groups in soil layers deeper than 12.5 cm.

Metástasis rectal de carcinoma lobulillar mamario / No disponible

No disponible

Quality improvement through teleradiology: opportunities and challenges.

Teleradiology is rapidly establishing its presence as an effective solution to the problem of provision of radiological services in remote locations. Although significant effort has been put into the development and establishment of quality assurance (QA) processes required for the implementation and conduct of this new technology, little attention has been given to the possible use of teleradiology in enhancing quality and safety of radiological practice, and as an alternative to conventional quality improvement (QI) initiatives. This paper critically evaluates teleradiology from the point of view of its potential use in QA/QI and considers its possible advantages as well as limitations. Considering the unique features of teleradiology such as remote access that can be simultaneous at multiple sites, rapid transfer of information and computerized data storage as well as good reproducibility and reliability of data, the authors argue that teleradiology represents an ideal tool which can not only be equivalent to other methods of QA in radiology but in some instances may be superior to them.

Are radiologists meeting the needs of Australian medical oncologists? Results of a national survey.

Although radiological evaluation plays an integral role in the management of oncology patients, little is known about which elements of such evaluation are most important or about how satisfied clinicians are with the quality of radiology services in cancer patients. We have developed a 36-item anonymous survey evaluating availability of and satisfaction with radiology services to medical oncologists. The survey was distributed to members of the Medical Oncology Group of Australia resident in Australia. We received 124 responses (51%). Most respondents (76.9%) were satisfied with their radiology services. Satisfaction correlated closely with the availability of standardized reporting and promptness of reporting (P < 0.001). Oncologists in private practise were more likely to receive prompt reports (P < 0.0001). Oncologists in public practice were more concerned about availability of CT scanning (P = 0.02). Services that were reported as less frequently available, despite being ranked as very important, included measurements of key lesions and comparison to previous studies. Standardized reporting was considered helpful by 91% of respondents. Only 32.5% of respondents reported receiving such a summary in more than 50% of cases and 21% never received such a summary. Our findings highlight the need for closer collaboration between oncologists and radiologists in order to address specific needs and develop optimal patterns of practise. Consideration should be given to standardization of reporting of radiology studies in oncology.

Renal parenchymal malakoplakia: an unusual cause of unilateral, diffuse renal enlargement.

Renal parenchymal malakoplakia is usually described as a multi- or unifocal process. We report an unusual case presenting with unilateral diffuse renal enlargement consistent with an early stage in the evolution of this disease.

Gadolinium-enhanced computed tomographic aortography.

Radiographic contrast agents using gadolinium have a better safety profile and photoelectric effect than iodinated contrast, allowing use where iodinated contrast is contraindicated. A case of gadolinium-enhanced computed tomographic aortography (CTA) for suspected thoracic dissection is reported. Aortic enhancement was sufficient for confident exclusion of an intimal flap. The findings were later confirmed by MRI. Vascular enhancement diminished below the diaphragm and tissue enhancement was minimal. Gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) may be used for CTA of the thoracic aorta, where the use of iodinated contrast is contraindicated. Multi-slice CT may expand the role of gadolinium enhancement in the future.

Radiology interventions in patients receiving low molecular weight heparin: timing is critical.

Recent advances in diagnosis and treatment of venous thromboembolism have been associated with increasing use of low molecular weight heparins (LMWH) for treatment and prophylaxis of this disease. Despite this trend for more widespread use of LMWH, little is known of their safety in patients undergoing radiology interventions. Differences between LMWH and unfractionated heparin and the implications of these differences on use of LMWH in the setting of radiological interventions are outlined.

Transperitoneal guide-wire or drainage catheter placement for guidance of laparoscopic marsupialization of lymphocoeles post renal transplantation.

BACKGROUND: Lymphocoeles post renal transplantation can be difficult to see laparoscopically. The objective of this study was to report a new technique of catheter or guide-wire placement for the guidance of laparoscopic marsupialization of symptomatic post renal transplant lymphocoeles, refractory to conservative therapy. METHODS: Conventional aseptic technique under local anaesthesia was used for guide-wire or catheter insertion, with the difference being the use of a transperitoneal approach. Computerized tomography (CT) or ultrasound (US) guidance was used. All lesions were confirmed to be sterile lymphocoeles beforehand by either needle aspiration or previous catheter drainage. RESULTS: Four catheters and one guide-wire were placed pre-operatively without complication. All cases underwent satisfactory laparoscopic marsupialization. No immediate complications were noted in any patient. The drainage catheters were inserted between 5 and 19 days before laparoscopic marsupialization, and guide-wire inserted immediately before. All patients proceeded to laparoscopic marsupialization. CONCLUSIONS: This technique offers precise guidance on laparoscopic surgery, is relatively simple to perform and no complications were experienced in this study. Its use is limited to sterile and benign lesions due to the risks of peritoneal seeding, making recurrent post-operative lymphocoeles ideally suited for this application.

Thoracic CT for the intensivist.

OBJECTIVE: To discuss the recent advances in computed tomography (CT) and to present a simplified approach to CT of the chest to facilitate the understanding and diagnosis of common acute thoracic abnormalities in the critically ill patient. DATA SOURCES: Published articles and texts on thoracic disorders and CT diagnosis. SUMMARY OF REVIEW: In the acutely ill patient with complex pulmonary and cardiac disorders a thoracic CT can be useful in determining the cardiac, pulmonary, pleural and mediastinal abnormalities present. With an understanding of the position and appearance of normal intrathoracic structures (and artifacts) acute thoracic disorders can be easily assessed by the non-radiologist, facilitating the correct diagnosis and the appropriate management. CONCLUSIONS: Thoracic CT offers the intensive care specialist the option of evaluating the pulmonary system, pleura, mediastinum, heart, pericardium, and aorta where plain radiographs are often inadequate. New mobile CT technology offers CT to patients confined to the intensive care unit due to haemodynamic instability.

Basic head CT for intensivists.

OBJECTIVE: To present a simplified approach to computed tomography (CT) of the head to facilitate the understanding and diagnosis of common acute cerebral abnormalities in the critically ill patient. DATA SOURCES: Published articles and texts on cerebral disorders and CT diagnosis. SUMMARY OF REVIEW: In the unconscious and acutely ill patient a head CT is often performed to assess the possibility of an organic or 'space occupying' cerebral lesion. While specialist radiological interpretation is often available during the day, when an 'out of hours' emergency occurs the diagnosis of an intracerebral abnormality often relies upon the intensivist's interpretation of the head CT scan. With an understanding of the position and appearance of normal intracerebral structures (and artifacts) common acute cerebral disorders can be easily assessed by the non-radiologist, facilitating the correct diagnosis and the appropriate management. CONCLUSIONS: Head CT is the commonest CT performed in the intensive care unit. In many patients who are sedated or ventilated, neurological examination is sometimes difficult and CT becomes important in clarifying patient's neurological status. A simple approach to the interpretation of brain CT images assists in the management of these cases.

Candida jejunitis: a rare cause of intestinal pneumatosis in the immunocompromised patient.

A case of fatal necrotizing jejunitis caused by Candida albicans is described in a patient with acute myeloid leukaemia undergoing chemotherapy. The diagnosis was made at autopsy. Computed tomography findings were of small bowel dilatation with pneumatosis.

Port site metastases after laparoscopic cholecystectomy for an unexpected gallbladder carcinoma.

Laparoscopic cholecystectomy is a proven, well-accepted surgical technique for removing the diseased gallbladder and has rapidly become the surgical procedure of choice over conventional open cholecystectomy. Radiologists must be aware of the possibility of inadvertent dissemination of incidental gallbladder cancer during laparoscopic cholecystectomy. We report a case of this unusual complication: a patient with port site metastases after laparoscopic cholecystectomy for an unexpected gallbladder carcinoma at an early stage.

[Inguinal bladder hernia in the adult]. / Hernias vesicales inguinales del adulto.

OBJECTIVE: To describe four additional cases of adult inguinal bladder hernia. METHODS: From 1986 to 1998, four cases of bladder inguinal herniation were diagnosed at our services. The etiology, diagnosis, treatment, associated conditions and complications are presented. RESULTS: Two cases had resulted from benign prostatic hyperplasia; one underwent TUR and the other was treated with alpha-blockers. The remaining two cases were due to prostatic carcinoma and were treated with hormone therapy. The bladder hernia was surgically repaired in three cases; the last patient refused surgery. CONCLUSIONS: A bladder hernia that is incidentally discovered during herniorrhaphy can be resolved without difficulty. However, problems may arise when an unsuspected bladder hernia is undetected due to preoperative bladder emptying and is included in the sutures of herniorrhaphy. When important bladder hernias are diagnosed preoperatively, surgical resolution is always indicated, as well as treatment by surgery or drugs of the urinary obstruction that contributed to the condition.

Chylothorax in Gorham's syndrome. A common complication of a rare disease.

One hundred forty-six cases of Gorham's syndrome are documented in the literature. Twenty-five (17 percent) patients have been reported to have chylothorax as a complication. To our knowledge, this high incidence of chylothorax has not been reported previously. We describe two such patients treated by thoracic duct ligation and compared our results with others to support early surgical intervention via a low right-sided thoracotomy in these cases.