Engineering Photon Statistics in a Spinor Polariton Condensate.

We implement full polarization tomography on photon correlations in a spinor exciton-polariton condensate. Our measurements reveal condensate pseudospin mean-field dynamics spanning from stochastic switching between linear polarization components, limit cycles, and stable fixed points, and their intrinsic relation to the condensate photon statistics. We optically harness the cavity birefringence, polariton interactions, and the optical orientation of an incoherent exciton reservoir to engineer photon statistics with precise control. Our results demonstrate a smooth transition from a highly coherent to a super-thermal state of the condensate polarization components.

Persistent Self-Induced Larmor Precession Evidenced through Periodic Revivals of Coherence.

Interferometric measurements of an optically trapped exciton-polariton condensate reveal a regime where the condensate pseudo-spin precesses persistently within the driving optical pulse. For a single 20 µs optical pulse, the condensate pseudo-spin undergoes over 10^{5} full precessions with striking frequency stability. The emergence of the precession is traced to polariton nonlinear interactions that give rise to a self-induced out-of-plane magnetic field, which in turn drives the system spin dynamics. The Larmor precession frequency and trajectory are directly influenced by the condensate density, enabling the control of this effect with optical means. Our results accentuate the system's potential for the realization of magnetometry devices and can lead to the emergence of spin-squeezed polariton condensates.

Optical Control of Couplings in Polariton Condensate Lattices.

We demonstrate deterministic control of the nearest and next-nearest neighbor coupling in the unit cell of a square lattice of microcavity exciton-polariton condensates. We tune the coupling in a continuous and reversible manner by optically imprinting potential barriers of variable height, in the form of spatially localized incoherent exciton reservoirs that modify the particle flow between condensates. By controlling the couplings in a 2×2 polariton cluster, we realize ferromagnetic, antiferromagnetic, and paired ferromagnetic phases and demonstrate the potential scalability of the system.

Transition from Propagating Polariton Solitons to a Standing Wave Condensate Induced by Interactions.

We explore phase transitions of polariton wave packets, first, to a soliton and then to a standing wave polariton condensate in a multimode microwire system, mediated by nonlinear polariton interactions. At low excitation density, we observe ballistic propagation of the multimode polariton wave packets arising from the interference between different transverse modes. With increasing excitation density, the wave packets transform into single-mode bright solitons due to effects of both intermodal and intramodal polariton-polariton scattering. Further increase of the excitation density increases thermalization speed, leading to relaxation of the polariton density from a solitonic spectrum distribution in momentum space down to low momenta, with the resultant formation of a nonequilibrium condensate manifested by a standing wave pattern across the whole sample.

Spin Order and Phase Transitions in Chains of Polariton Condensates.

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.

Steady-state serum concentrations of venlafaxine in patients with late-life depression. Impact of age, sex and BMI.

Diagnosis of late-life depression is given when depressive symptoms emerge in persons older than 65 years. Great care is needed when elderly patients receive psychopharmacotherapy due to altered pharmacokinetic status. As a consequence, age is considered to have a significant effect on serum concentrations of antidepressant drugs. The magnitudes of age-dependent changes, however, are uncertain. By utilizing a large therapeutic drug monitoring (TDM) database, this cross-sectional study aimed to retrospectively assess pharmacotherapy in elderly patients in comparison with their younger counterparts, when treated with venlafaxine, which is widely used to treat late-life depression. In addition, the influence of sex and body mass index (BMI) was evaluated. Serum concentrations of venlafaxine and its active metabolite O-desmethylvenlafaxine requested during routine TDM in two University Medical Centers in Germany were analyzed. Patients with concomitant CYP2D6 inhibiting drugs as co-medication were excluded. In total, 1,417 samples were available for the analysis. Elderly patients had by average 42% higher dose-adjusted serum concentrations (ng/mL/mg) of the active moiety (venlafaxine plus O-desmethylvenlafaxine) than younger patients. In addition, our study demonstrated that the difference between age groups is independent of sex and BMI. However, age groups only explain 4.5% of the total dose-adjusted serum concentration variation of the venlafaxine active moiety. Dose adjustments for venlafaxine are recommended in patients aged 65 years or older, particularly in elderly female patients who are exceptionally vulnerable to high serum concentrations of venlafaxine. TDM is recommended during venlafaxine pharmacotherapy.

Outcome predictors in acute surgical admissions for lower gastrointestinal bleeding.

AIM: The BLEED criterion is a triaging model for lower gastrointestinal bleeding (LGIB), which was developed and validated in the USA. We assessed the BLEED criteria in a UK population and aimed to elucidate factors that can be implemented for early risk stratification. METHOD: Patients were identified from a prospectively maintained surgical admission database at a central London teaching hospital. Data were collected on 26 clinical factors available on initial presentation. The primary-outcome end-points included severe bleeding (persistent bleeding within the first 24 h, blood transfusion, a decrease in haematocrit of ≥ 20% or recurrent bleeding after ≥ 24 hours of stability) and adverse outcome (emergency surgery to control bleeding, intensive care unit [ITU] admission or death). RESULTS: One hundred and eighty-four clinical episodes were identified, representing 3% of all surgical referrals. Twelve patients with upper gastrointestinal bleeding were excluded. Severe bleeding occurred in 110 (64%) patients. An adverse outcome was recorded in 20 (11.6%) patients, and 10 (5.4%) patients died during admission. The commonest aetiologies were diverticular disease, haemorrhoids and malignancy. Four prognosticators of adverse outcome were identified, these being: creatinine > 150 µm (P = 0.002); age > 60 years (P = 0.001); abnormal haemodynamic parameters on presentation (P = 0.05); persistent bleeding within the first 24 h (P = 0.05); and area under the receiver-operating characteristics curve (AUC) = 0.79. The BLEED criteria were shown to be nonpredictive (AUC = 0.60). CONCLUSION: The BLEED criterion was not shown to have any predictive value in this patient cohort. Our study has determined an independent set of prognostic factors that could be incorporated into initial triaging of patients presenting with LGIB. This may facilitate the early identification of patients requiring more aggressive resuscitation, admission to a monitored bed and consideration for early radiological or surgical intervention.

Quantum fluids of light in all-optical scatterer lattices.

One of the recently established paradigms in condensed matter physics is examining a system's behaviour in artificial potentials, giving insight into phenomena of quantum fluids in hard-to-reach settings. A prominent example is the matter-wave scatterer lattice, where high energy matter waves undergo transmission and reflection through narrow width barriers leading to stringent phase matching conditions with lattice band formation. In contrast to evanescently coupled lattice sites, the realisation of a scatterer lattice for macroscopic matter-wave fluids has remained elusive. Here, we implement a system of exciton-polariton condensates in a non-Hermitian Lieb lattice of scatterer potentials. By fine tuning the lattice parameters, we reveal a nonequilibrium phase transition between distinct regimes of polariton condensation: a scatterer lattice of gain guided polaritons condensing on the lattice potential maxima, and trapped polaritons condensing in the potential minima. Our results pave the way towards unexplored physics of non-Hermitian fluids in non-stationary mixtures of confined and freely expanding waves.

Synthetic band-structure engineering in polariton crystals with non-Hermitian topological phases.

Synthetic crystal lattices provide ideal environments for simulating and exploring the band structure of solid-state materials in clean and controlled experimental settings. Physical realisations have, so far, dominantly focused on implementing irreversible patterning of the system, or interference techniques such as optical lattices of cold atoms. Here, we realise reprogrammable synthetic band-structure engineering in an all optical exciton-polariton lattice. We demonstrate polariton condensation into excited states of linear one-dimensional lattices, periodic rings, dimerised non-trivial topological phases, and defect modes utilising malleable optically imprinted non-Hermitian potential landscapes. The stable excited nature of the condensate lattice with strong interactions between sites results in an actively tuneable non-Hermitian analogue of the Su-Schrieffer-Heeger system.

Tephra from the 1979 soufriere explosive eruption.

The explosive phase of the 1979 Soufriere eruption produced 37.5 x 10(6) cubic meters (dense-rock equivalent) of tephra, consisting of about 40 percent juvenile basaltic andesite and 60 percent of a nonjuvenile component derived from the fragmentation of the 1971-1972 lava island during phreatomagmatic explosions. The unusually fine grain size, poor sorting, and bimodality of the land deposit are attributed to particle aggregation and the formation of accretionary lapilli in a wet eruption column.

Soufriere volcano, st. Vincent: observations of its 1979 eruption from the ground, aircraft, and satellites.

Rapid response by earth, atmospheric, and space scientists made possible diverse observations during the explosive phase of the 1979 eruption of Soufriere Volcano. The 11 reports that follow indicate that, with the availability of appropriate personnel, equipment, and logistical support, a significant body of geophysical data can be gathered on short notice at erupting volcanoes in remote parts of the world.

Eruption of soufriere volcano on st. Vincent island, 1971-1972.

The Soufrière volcano in St. Vincent erupted from October 1971 to March 1972, as 80 x 10(6) m(3) of basaltic andesite lava was quietly extruded inside the mile-wide crater. The eruption was largely subaqueous, taking place in the 180-m-deep crater lake, and resulted in the emergence of a steep-sided island. The mild character of the eruption and the absence of seismic activity stand in direct contrast to the highly explosive character of the eruption of 1902 to 1903.

Eruption of the nevado del ruiz volcano, Colombia, on 13 november 1985: tephra fall and lahars.

A small Plinian eruption of the Nevado del Ruiz volcano in Colombia ejected 3.5 x 10(10) kilograms of mixed dacite and andesite tephra on 13 November 1985, with a maximum column height of 31 kilometers above sea level. Small pyroclastic flows and surges, generated during the initial stage of the eruption, caused surface melting of approximately 10% of the volcano's ice cap, leading to meltwater floods. The erosive floods incorporated soils and loose sediments from the volcano's flanks and developed into lahars, which claimed at least 25,000 lives.

Holocene eruptive activity of el chichon volcano, chiapas, Mexico.

Geologic and radiometric-age data indicate that El Chichón was frequently and violently active during the Holocene, including eruptive episodes about 600, 1250, and 1700 years ago and several undated, older eruptions. These episodes, involving explosive eruptions of sulfur-rich magma and associated dome-growth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichón's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.

Rectal cancer with macroscopic peritoneal involvement--clinical challenges and consequences.

OBJECTIVE: In gastrointestinal cancer, serosal involvement indicates advanced disease. We looked at the possible role of clinical peritoneal involvement (CPI) in local recurrences (LRs) and the overall survival of patients with rectal cancer (RC). METHOD: Between 1993 and 2002, 6404 patients were diagnosed with RC. Based on macroscopic findings at surgery and corresponding histological findings, 166 patients (3%) had CPI. Surgery was stratified according to type and extent of operation: as resective or nonresective surgery and as curative (R0) or noncurative (R1 or R2) resection. RESULTS: The presence of CPI was a negative factor for survival with a median of 15 months (95% CI, 12-19) in the presence of CPI compared with 65 months (95% CI, 61-70) without it (P < 0.001). In R0 resections, the median survival was 97 months (95% CI, 90-102) in patients without CPI compared with 48 months (95% CI, 22-74) in patients with CPI (P < 0.001). In R1 or R2 resections, the median survival was 16 months (95% CI, 15-17) in the absence of CPI and 9 months (95% CI, 8-10) in the presence of CPI. The LR rate in patients without CPI was 10.2% compared with 15.7% in patients with CPI (P = 0.022). CONCLUSIONS: Clinical peritoneal involvement is a significant detrimental prognostic factor for the LR of RC and survival in the absence of metastases. Observations from this large national cohort add to what is known about peritoneal involvement. Diagnosed CPI should be taken into consideration when adjuvant treatment strategies are addressed.

Palliative surgery for rectal cancer in a national cohort.

OBJECTIVE: Whether resection of the primary tumour is of benefit to patients with incurable rectal cancer (RC) remains a matter of debate. In this study we analyse prospectively recorded data from a national cohort. METHOD: Among 4831 patients diagnosed with RC between 1997 and 2001, 838 (17%) patients were treated with palliative surgery. Patients were stratified according to disease stage, age and type of surgery. RESULTS: A significantly longer median survival, 12 (range 10-13) months, was observed in patients treated with resection of the primary tumour compared with 5 (range 4-6) months in patients treated with nonresective procedures (P < 0.001). Median survival in months was significantly (P < 0.001) related to age (13; < 60 years of age, 10; 60 to 69 years, 7; 70 to 79 years, 6; >/= 80 years of age). In patients over 80 years, survival was similar regardless of the treatment. Thirty-day mortality varied from 2.5% to 20%, according to age groups. CONCLUSION: The longer survival observed in patients with resection of the primary tumour may partly be explained by patient selection. Elderly patients (>/= 80 years) had a similar survival, irrespective of resection of the primary tumour or not. Careful consideration of the individual patient, extent of disease and treatment-related factors are important in decision-taking for palliative treatment for patients with advanced RC.

Topical drug delivery to the posterior segment of the eye: anatomical and physiological considerations.

Drug delivery to the posterior segment of the eye is important for potentially treating various disorders in retina, choroid, vitreous humor and optic nerve. Due to anatomic membrane barriers and the lacrimal drainage it can be quite challenging to obtain therapeutic drug concentrations in the posterior parts of the eye after topical drug administration. Since the membrane barriers cannot be altered with non-invasive methods invasive methods such as direct drug injection into the vitreous humor and subconjunctival, subtenons capsule or suprascleral injections are gaining popularity. However, invasive methods can cause discomfort for the patient and can also lead to complications that are even more serious than the disease being treated. Alternatively, novel ophthalmic formulations can be developed that specifically target topical drug delivery to the posterior segment of the eye. Anatomical and physiological barriers in the eye are reviewed as well as the theoretical model of passive drug diffusion from the eye surface into the eye. It is shown that enhanced drug delivery through conjunctiva/sclera to retina can be obtained by formulating lipophilic drugs as hydrophilic drug/cyclodextrin complex solutions. Optimization of the delivery system by formulating the drug as a low-viscosity aqueous drug/cyclodextrin complex suspension results in sustained high concentrations of dissolved drug in the tear fluid which further increases the targeted drug delivery to the posterior segment.

Her-2/neu and INT2 proto-oncogene amplification in malignant breast tumors in relation to reproductive factors and exposure to exogenous hormones.

In previous studies in southern Sweden, early use of oral contraceptives has been found to be accompanied by an increased risk of developing premenopausal breast cancer, and the tumors developing in these patients have shown a more aggressive behavior. In the present study, amplification of the proto-oncogenes Her-2/neu (also known as ERBB2) and INT2 was studied in primary tumor specimens from 72 premenopausal women and was related to starting age of oral contraceptive use and other reproductive risk factors. Amplification of Her-2/neu was more common among early oral contraceptive users (i.e., those starting at less than or equal to 20 years of age) than among nonusers or late users (odds ratio [OR], 5.3; 95% confidence interval [CI], 1.6-16.7), whereas INT2 amplification did not differ significantly among those groups (OR, 0.9; 95% CI, 0.1-5.0). The likelihood of INT2 amplification was greater among users of progestins and those with a history of abortions before the first full-term pregnancy (OR, 9.0; 95% CI, 1.3-51.7; and OR, 18.6; 95% CI, 2.2-165.8, respectively). No significant relationships were found between proto-oncogene amplification and the variables of parity, age at first full-term pregnancy, or late abortion. The increased ORs persisted after adjustment for age at diagnosis and other risk factors. The findings suggest that the higher rate of Her-2/neu amplification among early oral contraceptive users is an effect of the oral contraceptive use per se rather than of the relative youth of the users. Moreover, the relationship between progestin use and early abortion and amplification of the INT2 gene is biologically plausible.

HER-2/neu amplification predicts poor survival in node-positive breast cancer.

HER-2/neu protooncogene amplification and protein expression were analyzed with slot blot and Western blot techniques, respectively, in more than 300 invasive primary breast tumors of all stages. Amplification (2- greater than 30 copies) was found in 17% of these tumors and high expression was seen in 19%. There was a striking coincidence between gene amplification and high expression. Tumors associated with many involved axillary lymph nodes or with Stage IV disease were more often HER-2/neu amplified or overexpressed. Furthermore, gene alteration was strongly correlated with the absence of steroid receptors and with larger tumor size. High expression without gene amplification was seen in a minor subset of tumors of less aggressive character. Neither amplification nor overexpression was correlated with disease outcome for patients with negative axillary lymph nodes. For node-positive patients, however, HER-2/neu amplification was a significant predictor of early relapse and death (median follow-up = 45 months), and a similar trend, although not significant, existed for high gene expression. Multivariate analyses indicated that HER-2/neu alterations were not independent predictors of patient outcome.

ERBB2 amplification in breast cancer with a high rate of proliferation.

The ERBB2 proto-oncogene was studied in 539 invasive primary breast tumors and was found amplified (2- greater than 30 copies) in 19%. Amplification was correlated to most known risk factors, including; large tumor size, lymph node positivity and many tumor involved nodes, advanced stage, low patient age (less than 40 years), non-diploidy and hypertetraploidy, and most significantly (P less than 0.00001) to the absence of steroid receptors and to a high rate of proliferation (flow cytometric determined S phase fraction). ERBB2 amplification was strongly associated (P less than 0.0001) with early recurrence and death in breast cancer among node-positive patients. This connection did not, however, remain in multivariate analyses. No correlations to clinical outcome were seen among node-negative patients. Similarly, non-diploid, but not diploid, amplified tumors were particularly aggressive. Furthermore, ERBB2 amplification was associated with a high rate of proliferation and poor prognosis in steroid receptor positive, but not receptor negative tumors. In progesterone receptor positive breast cancer, amplification was an independent and with node status equally powerful (P less than 0.0001) predictor of poor survival. It is concluded that ERBB2 activity is related to an increased tumor growth rate but not directly to metastasizing ability. Its clinical relevance as a prognostic factor may be in selecting a high risk subgroup of breast cancer, in general considered as being of good prognosis.