Low elevation of Svalbard glaciers drives high mass loss variability

Compared to other Arctic ice masses, Svalbard glaciers are low-elevated with flat interior accumulation areas, resulting in a marked peak in their current hypsometry (area-elevation distribution) at  ~450 m above sea level. Since summer melt consistently exceeds winter snowfall, these low-lying glaciers can only survive by refreezing a considerable fraction of surface melt and rain in the porous firn layer covering their accumulation zones. We use a high-resolution climate model to show that modest atmospheric warming in the mid-1980s forced the firn zone to retreat upward by  ~100 m to coincide with the hypsometry peak. This led to a rapid areal reduction of firn cover available for refreezing, and strongly increased runoff from dark, bare ice areas, amplifying mass loss from all elevations. As the firn line fluctuates around the hypsometry peak in the current climate, Svalbard glaciers will continue to lose mass and show high sensitivity to temperature perturbations.

Svalbard glaciers are among the lowest ice masses in the Arctic, with a peak in glacier area below 450 m elevation. Using a high-resolution climate model, here the authors show that a modest warming in the mid-1980s propagated meltwater runoff above the glacier area peak, amplifying Svalbard mass loss from all elevations.

“I Don't See it so it Must be to my Left:” Rehabilitation of Visuospatially Impaired Adults

Patients who are visually impaired because of brain damage often show a visuospatial syndrome characterized by disturbances of spatial orientation and determined behavior. The lesion may be located in the frontal cortex or in the right parietal cortex of the brain; recent research shows that the determination of spatial behavior is impaired. Emphasis in the rehabilitation of these patients should be shifted from perceptual to performance orientation. It is essential for the individual to gain insight into his or her specific impairment and for the professional to work cooperatively using the patient's own strategies.

A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps

Melting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze meltwater. Consequently, GICs runoff increases 65% faster than meltwater production, tripling the post-1997 mass loss to 36±16 Gt^-1, or ∼14% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased meltwater production. This underlines the very different response of the GICs and GrIS to atmospheric warming.

Separation of Time Scales in a Quantum Newton's Cradle

We provide detailed modeling of the Bragg pulse used in quantum Newton's-cradle-like settings or in Bragg spectroscopy experiments for strongly repulsive bosons in one dimension. We reconstruct the postpulse time evolution and study the time-dependent local density profile and momentum distribution by a combination of exact techniques. We further provide a variety of results for finite interaction strengths using a time-dependent Hartree-Fock analysis and bosonization-refermionization techniques. Our results display a clear separation of time scales between rapid and trap-insensitive relaxation immediately after the pulse, followed by slow in-trap periodic behavior.

Complete Generalized Gibbs Ensembles in an Interacting Theory

In integrable many-particle systems, it is widely believed that the stationary state reached at late times after a quantum quench can be described by a generalized Gibbs ensemble (GGE) constructed from their extensive number of conserved charges. A crucial issue is then to identify a complete set of these charges, enabling the GGE to provide exact steady-state predictions. Here we solve this long-standing problem for the case of the spin-1/2 Heisenberg chain by explicitly constructing a GGE which uniquely fixes the macrostate describing the stationary behavior after a general quantum quench. A crucial ingredient in our method, which readily generalizes to other integrable models, are recently discovered quasilocal charges. As a test, we reproduce the exact postquench steady state of the Néel quench problem obtained previously by means of the Quench Action method.

GRACE, time-varying gravity, Earth system dynamics and climate change

Continuous observations of temporal variations in the Earth's gravity field have recently become available at an unprecedented resolution of a few hundreds of kilometers. The gravity field is a product of the Earth's mass distribution, and these data-provided by the satellites of the Gravity Recovery And Climate Experiment (GRACE)-can be used to study the exchange of mass both within the Earth and at its surface. Since the launch of the mission in 2002, GRACE data has evolved from being an experimental measurement needing validation from ground truth, to a respected tool for Earth scientists representing a fixed bound on the total change and is now an important tool to help unravel the complex dynamics of the Earth system and climate change. In this review, we present the mission concept and its theoretical background, discuss the data and give an overview of the major advances GRACE has provided in Earth science, with a focus on hydrology, solid Earth sciences, glaciology and oceanography.

Quenching the anisotropic heisenberg chain: exact solution and generalized Gibbs ensemble predictions

We study quenches in integrable spin-1/2 chains in which we evolve the ground state of the antiferromagnetic Ising model with the anisotropic Heisenberg Hamiltonian. For this nontrivially interacting situation, an application of the first-principles-based quench-action method allows us to give an exact description of the postquench steady state in the thermodynamic limit. We show that a generalized Gibbs ensemble, implemented using all known local conserved charges, fails to reproduce the exact quench-action steady state and to correctly predict postquench equilibrium expectation values of physical observables. This is supported by numerical linked-cluster calculations within the diagonal ensemble in the thermodynamic limit.

High interstitial fluid pressure (IFP) and hypoxia as biomarkers of cisplatin chemoradiation response in advanced cervix cancer

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Background: Chemoradiotherapy (CRT) has been shown to improve survival compared to RT alone for locally advanced cervix cancer. The tumour microenvironment in cervix cancer is also known to influence disease progression and response to treatment. In this prospective study, pre-treatment tumour hypoxia and interstitial fluid pressure (IFP) were examined as potential biomarkers of improved treatment effectiveness in a cohort of patients treated with definitive radiation alone, or with the addition of concurrent cisplatin CRT. Methods: Between April 1994 and January 2006, 309 eligible patients with cervix cancer were entered into a prospective study of hypoxia and IFP prior to definitive treatment. Patients accrued between 1994 and 1999 (n = 115) were treated with RT alone, and those accrued between 2000 and 2006 (n = 194) received RT and concurrent weekly cisplatin CRT. Clinical characteristics were similar between the two cohorts except pelvic lymph node metastases were more frequent in the CRT cohort (42% vs. 19%, p = 0.0005), likely due to changes in definition of positive nodes on CT or MR imaging. The median follow-up was 3.6 years (2.9 years for CRT and 7.8 years for RT). Results: The use of CRT improved outcome in hypoxic tumors compared to RT (57% 3-yr DFS vs. 42%, p = 0.045) with a trend to improved DFS in patients with high IFP tumors (57% 3-yr DFS vs. 44% for RT alone, p = 0.056). A strong interaction was identified between IFP and treatment (CRT vs. RT, p = 0.007). After correcting for the effects of clinical prognostic factors, cisplatin significantly improved DFS in the high IFP group (p = 0.02), and showed a trend towards improved DFS in those with hypoxia (p = 0.1). In patients with both high IFP and hypoxia a similar benefit of cisplatin was seen. Conclusions: Patients with high IFP and hypoxic tumours may selectively benefit from the addition of concurrent cisplatin CRT to their treatment regimen. This observation is contrary to an effect of high IFP on impaired drug delivery, but may reflect reduced DNA repair under hypoxic conditions, which could facilitate cell killing with both radiation and cisplatin chemotherapy.

No significant financial relationships to disclose.

Maximal neutropenia during chemotherapy and radiotherapy is significantly associated with the development of acute radiation-induced dysphagia in lung cancer patients

BACKGROUND

Acute dysphagia is a distressing dose-limiting toxicity after concurrent chemoradiation or high-dose radiotherapy for lung cancer. We therefore identified factors associated with the occurrence of acute dysphagia in lung cancer patients receiving radiotherapy alone or combined with chemotherapy.

PATIENTS AND METHODS

Radiotherapy, chemotherapy and patient characteristics were analyzed using ordinal regression analysis as possible predictors for acute dysphagia (CTCAE 3.0) in 328 lung cancer patients treated with curative intent.

RESULTS

The most significant association was seen between the maximal grade of neutropenia during chemoradiation and dysphagia, with an odds ratio increasing from 1.49 [95% confidence interval (CI) 0.63-3.54, P = 0.362] for grade 1-2 neutropenia to 19.7 (95% CI 4.66-83.52, P < 0.001) for patients with grade 4 neutropenia. Twice-daily schedule, mean esophageal dose and administration of chemotherapy were significant predictive factors. By combining these factors, a high-performance predictive model was made. On an individual patient level, 64% of patients were correctly classified and only 1.2% of patients were misclassified by more than one grade.

CONCLUSIONS

The maximal neutrophil toxicity during concurrent chemotherapy and radiotherapy is strongly associated with the development of acute dysphagia. A multivariate predictive model was developed.

Non-invasive 19F MR spectroscopy of 5-fluorocytosine to 5-fluorouracil conversion by recombinant Salmonella in tumours

The aim of this study was to evaluate the applicability of fluorine-19 magnetic resonance spectroscopy (¹⁹F MRS) for monitoring in vivo the conversion of 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) after using an attenuated Salmonella Typhimurium strain recombinant to provide cytosine deaminase (TAPET-CD). The ¹⁹F MRS measurements were done on mice bearing the human colon tumour xenograft (HCT116). The intratumoural conversion is greater when TAPET-CD/5-FC is delivered intratumourally (i.tu.) than when TAPET-CD is delivered intravenously (i.v.) and 5-FC intraperitoneally (i.p.). Repeat measurements of the same tumour also yielded important information on the tumour colonization by TAPET-CD through the correlated 5-FC to 5-FU conversion efficacy. The in vivo MRS spectra were confirmed by in vitro¹⁹F MRS of perchloric acid extracts of the tumour tissue. No 5-FU metabolites were detectable in vivo in the tumours. However, the in vitro measurements revealed, besides 5-FC and 5-FU, the presence of small amounts of catabolites. Finally, spectra obtained in vitro from liver extracts of tumour-bearing mice treated i.tu. with TAPET-CD/5-FC showed no 5-FU and only little amounts of catabolites. Our data illustrate most importantly the potential of ¹⁹F MRS to monitor biologically-based treatments involving cytosine deaminase.

Tumor-specific gene delivery using genetically engineered bacteria

The loco-regional control of cancer remains a major contributor to the treatment outcome for many cancer patients prescribed conventional radiotherapy or chemotherapy. Failure of treatment coupled with the realisation that cancer is essentially a genetic disease has led to development of many clinical protocols based on gene therapy. In this review, we will describe an alternative gene delivery system based on the use of non-pathogenic bacteria. Tumor regressions have been reported long ago in patients with bacterially infected tumors, suggesting that bacteria could target tumors and have local anti-tumor effects. The basis of this phenomenon is attributable to the unique properties of the tumor micro-environment. The presence of hypoxic and/or necrotic areas provides a haven for a number of anaerobic bacteria and over the past 60 years, several strains of anaerobic bacteria have been shown to localise within and cause cell lysis of experimental animal tumors. One of the most important strains in that context is Clostridium. Other bacteria have also been implicated in experimental anti-cancer settings. Of these, attenuated Salmonella strains capable of both selective amplification within tumors and expression of effector genes encoding therapeutic proteins are probably the most promising. We will discuss the potential advantages and the pitfalls of this alternative delivery approach. We will emphasize the importance of hypoxia in solid tumors and discuss the potential of radiation-inducible promoters and combined treatment modalities, involving vascular targeting and radiotherapy. We believe that this approach will act in a complementary way to current radiotherapy and chemotherapy treatments of solid tumors.

A comparison of amodiaquine and sulfadoxine-pyrimethamine as first-line treatment of falciparum malaria in Kenya

A randomized 14-day study in vivo compared the response of Plasmodium falciparum malaria to amodiaquine (35 mg/kg) and sulfadoxine-pyrimethamine (sulfadoxine, 25 mg/kg) in symptomatic outpatients at 2 sites in northern and western Kenya during 1993. Of the 239 patients recruited, 181 (76%) completed the study [84 (46%) on amodiaquine and 97 (54%) on sulfadoxine-pyrimethamine]. There were no significant differences in the parasitological, clinical or haematological responses between the 2 drug groups in both areas, with 18.5% resistance to amodiaquine versus 9.5% for sulfadoxine-pyrimethamine in the north and 35.1% against amodiaquine versus 34.5% for sulfadoxine-pyrimethamine in the west. In both sites defervescence was significantly more rapid with amodiaquine (P < 0.05) and true clinical failure (symptomatic illness with recurrent parasitaemia) was unusual (9%). As high-level resistance to chloroquine is widespread, both drugs are valuable alternatives. However, the significantly higher levels of resistance in the west may be a sign of the increased drug pressure in this holoendemic area and send an important warning concerning resistance to sulfadoxine-pyrimethamine.

Endoscopic treatment of the hypopharyngeal (Zenker's) diverticulum

Over the years the techniques for endoscopic treatment of Zenker's diverticulum have been improved. Initially, in 1964, we used the electrocoagulation technique as described by Dohlman, but currently we prefer to sever the tissue bridge between the diverticulum and esophagus with the CO2 laser under microscopic control. The results of endoscopic treatment in 507 patients with a diverticulum are discussed. It is concluded that endoscopic treatment can readily be performed with good results, especially in the case of elderly patients in a poor general condition.

Late onset asthma?

A 77 yr old male was referred for dyspnoea and recurrent infections of the lower airways for the previous five months. On the lateral chest roentgenogram a process in the tracheal area was found, and during bronchoscopy a polypoid tumour was seen about four centimetres above the main carina. It appeared to be a benign endotracheal tumour which was removed after coagulation by a Neodymium yttrium aluminium garnet (YAG) laser.

Late onset asthma?

A 77 yr old male was referred for dyspnoea and recurrent infections of the lower airways for the previous five months. On the lateral chest roentgenogram a process in the tracheal area was found, and during bronchoscopy a polypoid tumour was seen about four centimetres above the main carina. It appeared to be a benign endotracheal tumour which was removed after coagulation by a Neodymium yttrium aluminium garnet (YAG) laser.

Amyloid tumour resected by laser therapy

We report a patient presenting with dyspnoea, cough and fever with a middle lobe atelectasis. Amyloid deposits in the bronchial wall caused almost complete obstruction of the middle lobe bronchus. The patient was treated with neodymium yttrium aluminium garnet (NdYAG) laser photoresection resulting in complete clearance of the middle lobe bronchus. Laser therapy has to be considered as first-line therapy for patients with endobronchial amyloidosis.

Amyloid tumour resected by laser therapy

We report a patient presenting with dyspnoea, cough and fever with a middle lobe atelectasis. Amyloid deposits in the bronchial wall caused almost complete obstruction of the middle lobe bronchus. The patient was treated with neodymium yttrium aluminium garnet (NdYAG) laser photoresection resulting in complete clearance of the middle lobe bronchus. Laser therapy has to be considered as first-line therapy for patients with endobronchial amyloidosis.

Pathogenesis and endoscopic treatment of the hypopharyngeal (Zenker's) diverticulum

The authors review the literature about the pathogenesis -still unknown- of Zenker's diverticulum as well as their experience of endoscopic treatment of this disease. From 1964 till 1988, they have treated endoscopically 507 patients, 323 by electrocoagulation, 184 by CO2-laser. The endoscopic procedure is described, consisting in precise division of the tissue bridge between the oesophagus and the diverticulum by micro-endoscopic surgery under general anesthesia. In recent years, the CO2-laser was found preferable, since it may cause less tissue necrosis and consequently less fibrous scar tissue. The results were very favourable, with more than 99% of the patients satisfied. Although many patients were old and in poor condition, only one patient died two days after operation because of cardiac failure. Complications such as bleeding, emphysema, mediastinitis and stenosis were seen in 5% of the patients, but in most cases there complications were mild and conservative therapy was sufficient. Stenosis occurred in 8 patients treated by electrocoagulation and in none of the patients treated by laser. Microendoscopic surgery is a safe and efficient method of therapy for the hypopharyngeal diverticulum.

[Stridor in children]

Stridor is the presenting symptom of abnormalities of larynx and trachea in children. The anatomical differences in size and consistency of the larynx play a crucial role in stridor in children as compared with adults. From 1983 to 1988, 81 children (65 males, 16 females) with severe or prolonged stridor were admitted to our hospital. Thorough examination, including endoscopy of larynx and trachea and radiology revealed various congenital abnormalities and acquired conditions as the cause of stridor. Congenital laryngeal anomalies accounted for stridor in 26 children, there were 12 children with congenital tracheal or vascular anomalies, 28 with infectious diseases and 15 with other diseases. Intubation and (or) tracheotomy were performed in one-third of the patients: 5 of them died of severe complications. For proper treatment of children with stridor it is essential to investigate its aetiology carefully.

Laser surgery in lingual tonsil hyperplasia

Modern techniques have reduced the long existing reluctance to perform lingual tonsillectomy. The results of treatment of hyperplasia of the lingual tonsil with the carbon dioxide laser in 32 patients are presented. After exposure with a special endoscope the lingual tonsil can be vaporized or excised under microscopic control with promising results, far superior to the results obtained with other surgical techniques. Since the success rate of the surgery depends on the diagnostic criteria for applying this therapy, a careful selection of patients is essential.