Evolution of Temporal Coherence in Confined Exciton-Polariton Condensates.

We study the influence of spatial confinement on the second-order temporal coherence of the emission from a semiconductor microcavity in the strong coupling regime. The confinement, provided by etched micropillars, has a favorable impact on the temporal coherence of solid state quasicondensates that evolve in our device above threshold. By fitting the experimental data with a microscopic quantum theory based on a quantum jump approach, we scrutinize the influence of pump power and confinement and find that phonon-mediated transitions are enhanced in the case of a confined structure, in which the modes split into a discrete set. By increasing the pump power beyond the condensation threshold, temporal coherence significantly improves in devices with increased spatial confinement, as revealed in the transition from thermal to coherent statistics of the emitted light.

Experimental Verification of the Very Strong Coupling Regime in a GaAs Quantum Well Microcavity.

The dipole coupling strength g between cavity photons and quantum well excitons determines the regime of light matter coupling in quantum well microcavities. In the strong coupling regime, a reversible energy transfer between exciton and cavity photon takes place, which leads to the formation of hybrid polaritonic resonances. If the coupling is further increased, a hybridization of different single exciton states emerges, which is referred to as the very strong coupling regime. In semiconductor quantum wells such a regime is predicted to manifest as a photon-mediated electron-hole coupling leading to different excitonic wave functions for the two polaritonic branches when the ratio of the coupling strength to exciton binding energy g/E_{B} approaches unity. Here, we verify experimentally the existence of this regime in magneto-optical measurements on a microcavity characterized by g/E_{B}≈0.64, showing that the average electron-hole separation of the upper polariton is significantly increased compared to the bare quantum well exciton Bohr radius. This yields a diamagnetic shift around 0 detuning that exceeds the shift of the lower polariton by 1 order of magnitude and the bare quantum well exciton diamagnetic shift by a factor of 2. The lower polariton exhibits a diamagnetic shift smaller than expected from the coupling of a rigid exciton to the cavity mode, which suggests more tightly bound electron-hole pairs than in the bare quantum well.

Prototype of a bistable polariton field-effect transistor switch.

Microcavity exciton polaritons are promising candidates to build a new generation of highly nonlinear and integrated optoelectronic devices. Such devices range from novel coherent light emitters to reconfigurable potential landscapes for electro-optical polariton-lattice based quantum simulators as well as building blocks of optical logic architectures. Especially for the latter, the strongly interacting nature of the light-matter hybrid particles has been used to facilitate fast and efficient switching of light by light, something which is very hard to achieve with weakly interacting photons. We demonstrate here that polariton transistor switches can be fully integrated in electro-optical schemes by implementing a one-dimensional polariton channel which is operated by an electrical gate rather than by a control laser beam. The operation of the device, which is the polariton equivalent to a field-effect transistor, relies on combining electro-optical potential landscape engineering with local exciton ionization to control the scattering dynamics underneath the gate. We furthermore demonstrate that our device has a region of negative differential resistance and features a completely new way to create bistable behavior.

Observation of the Transition from Lasing Driven by a Bosonic to a Fermionic Reservoir in a GaAs Quantum Well Microcavity.

We show that, by monitoring the free carrier reservoir in a GaAs-based quantum well microcavity under nonresonant pulsed optical pumping, lasing supported by a fermionic reservoir (photon lasing) can be distinguished from lasing supported by a reservoir of bosons (polariton lasing). Carrier densities are probed by measuring the photocurrent between lateral contacts deposited directly on the quantum wells of a microcavity that are partially exposed by wet chemical etching. We identify two clear thresholds in the input-output characteristic of the photoluminescence signal which can be attributed to polariton and photon lasing, respectively. The power dependence of the probed photocurrent shows a distinct kink at the threshold power for photon lasing due to an increased radiative recombination of free carriers as stimulated emission into the cavity mode sets in. At the polariton lasing threshold, on the other hand, the nonlinear increase of the luminescence is caused by stimulated scattering of exciton polaritons to the ground state which do not contribute directly to the photocurrent.

Anomalies of a nonequilibrium spinor polariton condensate in a magnetic field.

We observe a strong variation of the Zeeman splitting of exciton polaritons in microcavities when switching between the linear regime, the polariton lasing, and photon lasing regimes. In the polariton lasing regime the sign of Zeeman splitting changes compared to the linear regime, while in the photon lasing regime the splitting vanishes. We additionally observe an increase of the diamagnetic shift in the polariton lasing regime. These effects are explained in terms of the nonequilibrium "spin Meissner effect."

Room temperature polariton light emitting diode with integrated tunnel junction.

We present a diode incorporating a large number (12) of GaAs quantum wells that emits light from exciton-polariton states at room temperature. A reversely biased tunnel junction is placed in the cavity region to improve current injection into the device. Electroluminescence studies reveal two polariton branches which are spectrally separated by a Rabi splitting of 6.5 meV. We observe an anticrossing of the two branches when the temperature is lowered below room temperature as well as a Stark shift of both branches in a bias dependent photoluminescence measurement.

[Severe leukopenia and bone marrow hypoplasia with gelatinous transformation in anorexia nervosa]. / Schwere Leukopenie und Knochenmarkhypoplasie mit gelatinöser Transformation bei Anorexia nervosa.

HISTORY AND ADMISSION FINDINGS: A 26-year-old woman was admitted because of excessive weight loss: her body mass index was 11.3 kg/m (2). She reported an adequate food intake and denied fear of gaining weight. INVESTIGATIONS: The leukocyte count on admission was 2.0/nl. Bone marrow biopsy showed gelatinous bone marrow transformation with hypocellularity. Psychiatric examination and observation of the patient's eating behavior revealed symptoms typical of anorexia nervosa. DIAGNOSIS, TREATMENT AND COURSE: Because of the diagnosis of anorexia nervosa behaviour therapy was started. During the following months the patient continually gained weight. But it took nine months for leukocyte count to be normal, by which time her body mass index had risen to 17.8 kg/m (2). CONCLUSION: Severe weight loss in anorexia nervosa may lead to leukopenia and gelatinous bone marrow transformation. The abnormal leukocyte count can become normal by maintaining body weight within the normal range.

[Chronic cough and pulmonary infiltration]. / Chronischer Husten und pulmonales Infiltrat.

HISTORY: A 56-year-old man complain of chronic cough for 6 months without further clinical problems. The patient was otherwise in good health and showed only a moderate bronchial sound at the left ventral paracordial region. INVESTIGATIONS: Thorax X-ray revealed an infiltrate in the lingula with segmental borders. The CT scan showed air bronchogramms and bilateral more small infiltrates. DIAGNOSIS, TREATMENT, CLINICAL COURSE: Bronchoscopic transbronchial biopsies revealed a BALT-lymphoma. A seven years old chest X-ray showed the lingual infiltrate in nearly the same extension as the current X-ray. Because of the disseminated manifestation, the slow course and the good performance status we did not start a palliative chemotherapy so far. CONCLUSION: Any pulmonary infiltrate which looks like pneumonia must be given a definite diagnosis if there are no clinical signs of infection.

[Uncommon course of radiation-induced pneumonitis with subsequent bronchiolitis obliterans with organizing pneumonia (BOOP) in a female with breast cancer]. / Ungewöhnlicher Verlauf einer Strahlenpneumonitis mit nachfolgender Bronchiolitis obliterans mit organisierender Pneumonie (BOOP) bei einer Patientin mit Mammakarzinom.

Radiation-induced pneumonitis is a familiar complication of breast cancer radiotherapy, whereas bronchiolitis obliterans with organizing pneumonia occurs extremely rarely after this treatment. Consequently, testing for BOOP is rarely included in differential diagnosis. This results in delayed diagnosis, so that treatment is ultimately commenced too late. The infiltrations are often located in the unirradiated lung, impeding diagnosis. The radiotherapy-induced BOOP-reaction that can also occur after typical radiation pneumonitis is illustrated by reference to a characteristic case report.

[Non-tubercular mycobacterial infection of the lungs due to Mycobacterium smegmatis]. / Nichttuberkulöse Mykobakteriose der Lungen durch Mycobacterium smegmatis.

Nontuberculous mycobacteriosis due to M. smegmatis is a rarity. We report on the case of a 51 year old male HIV-seronegative patient without predisposing bronchopulmonary disease, but with a state after gastrectomy and splenectomy who developed unproductive cough, night sweat and weight loss. The chest radiograph and thoracic CT showed wide-spread bilateral patchy infiltrations. Histological examination of transbronchial biopsies revealed chronic carnificating pneumonia. A perhoracic fine-needle biopsy showed caseating epitheloid cell granulomas with acid fast bacilli. These were identified as M. smegmatis by PCR with subsequent sequencing. Acid fast bacilli could not be detected microscopically neither in sputum nor in bronchial secretions, however M. smegmatis has been repeatedly detected by culture in these materials. In neither material tubercle bacilli have been detected by nucleic acid amplification (NAT) or culture. Immunologic investigations revealed a reduced number of CD4+ lymphocytes and a reduction of interferon alpha- and -gamma-synthesis by peripheral blood mononuclear cells. Treatment with Rifabutin, Ethambutol, Clarithromycin and Ofloxacin resulted in complete clinical and roentgenological resolution.

Interstitial lung disease induced by endogenous Candida albicans.

We report on a 64-year old woman with an interstitial lung disease which had characteristics of hypersensitivity pneumonitis. Severe febrile attacks with impairment of ventilation and diffuse poorly defined radiodensities and ground glass opacities on chest x-ray occured repeatedly. Laboratory data showed hypoxemia, leukopenia and circulating Candida albicans (C.a.)-antigen. Bronchoalveolar lavage revealed an increase in neutrophils. Transbronchial biopsies showed lymphocytic alveolitis, bronchiolitis obliterans and epitheloid cell granulomas. IgG and IgA and the lymphocyte proliferation assay were positive with C.a.-antigen. C.a. was detected in the feces. Intradermal skin test with C.a. showed a positive immediate and late phase reaction and inhalative provocation test with C.a.-antigen was positive. After antimycotic treatment the symptoms resolved completely and long-lasting. We conclude that the disease was induced by C.a.-antigen reaching the lungs from the intestinal tract via the bloodstream.

[Pulmonary microcalcification with miliary foreign-body granulomas. Residuals of cured Pneumocystis carinii pneumonia in AIDS]. / Pulmonale Mikrokalzifikationen mit miliaren Fremdkörpergranulomen. Residuen einer abgeheilten Pneumocystis-carinii-Pneumonie bei AIDS.

Pneumocystis carinii pneumonia (PCP) is one of the most frequent infectious lung diseases in immunocompromised patients, especially in AIDS cases. The present case report describes pulmonary miliary microcalcifications with and without foreign-body reaction in a patient with successfully treated PCP who was known to have AIDS. This form of residues of completely healed PCP tends to be rare. Other infectious granulomas, foreign-body granulomas and sarcoidosis must be differentially diagnosed. After cautious decalcification, pneumocysts can be demonstrated with methamine silver (Grocott). It is important to be aware that PCP can also undergo spontaneous cure, so that miliary microcalcifications may then be the sole pointer to the presence of AIDS.

Intermittent activity-induced hemobilia caused by liver hemangioma.

BACKGROUND: Intestinal bleeding of unknown origin can lead to a difficult workup. Abdominal colic, melena/hematemesis, and jaundice represent the pathognomonic triad for hemobilia, but clinical presentation and etiology of this entity are varying. Seldom all of these symptoms are present, and rarely does hemobilia cause melena or hematemesis. Often the correct diagnosis is missed. Patients frequently have a long history of complaints and inadequate therapy. CASE REPORT: We report on a patient who complained of repeated, severe epigastric pain and massive melena induced by exercise activity. After 2 years of complaints and an unnecessary operation, ultrasound detected a liver hemangioma. It was supposed that the hemangioma was causing hemobilia during strenuous physical activity. The patient underwent a partial liver resection to eliminate the hemangioma. All complaints resolved, and the patient remained asymptomatic postoperatively. CONCLUSIONS: Physicians should be aware of hemobilia as a rare cause of upper gastrointestinal bleeding, especially if esophagogastroduodenoscopy cannot demonstrate any bleeding source. Ultrasound is able to visualize many diseases leading to hemobilia and should be integrated into the early workup of unclear intestinal bleedings.

Hypersensitivity alveolitis induced by endogenous candida species

We report the case of a 64-year old woman with severe attacks of allergic alveolitis occurring frequently independent of a concrete place. These attacks were regularely preceded by diarrhoe. Laboratory data showed marked leukopenia and circulating Candida albicans (C.a.)-antigen. Bronchoalveolar lavage revealed an increase in neutrophils (13%). Transbronchial biopsies showed focal alveolitis and focal septal fibrosis with bronchiolitis obliterans and an epitheloid cell granuloma. Immunohistochemical examination revealed C.a.-antigen in alveolar macrophages. In the faeces a high amount of C.a. and C. glabrata was detected. In serum IgG and IgA were positive against C.a., IgE against C.a. was negative. Lymphocyte proliferation assay with C.a.-antigen was positive. Intradermal skin test with C.a. showed positive immediate and late phase reaction. Furthermore inhalation challenge with C.a.-antigen was positive. A febrile reaction with chills, dyspnea and hypoxemia and leukocytosis in peripheral blood occured after 6 hours. Lung function showed a predominantly obstructive impairment of ventilation. An extensive search for other IgG- or IgE-mediated allergies (other fungi, environmental or food allergens) was completely negative. Investigation of the gastrointestinal tract did not show any abnormality exept the detection of lactose intolerance. There was no fungal growth in the patients flat. After initiation of antimycotic treatment the symptoms resolved completely. - We conclude that the disease was induced by C.a.-antigen reaching the lungs from the intestinal tract via the bloodstream. It is still a matter of debate whether an additional factor is necessary for the antigen to penetrate the intestinal mucosa.

[Tumor simulating primary pulmonary cryptococcosis in an immunocompetent patient. A contribution to differential diagnosis]. / Als Tumor imponierende primäre pulmonale Kryptokokkose bei einer immunkompetenten Patientin. Ein Beitrag zur Differentialdiagnose.

Case report of a primary cryptococcosis of the lung in a 78-year old non-immunocompromised female. The patient presented with a mass in the right upper lobe, highly suspicious of lung cancer. Cryptococcus finally was detected on repeated biopsies from ulcerated and necrotic bronchial mucosa. A clinical work-up showed no evidence of dissemination and no signs of immunoinsufficiency. Mass reduction in the lung was achieved under therapy with fluconazol.

[Histomorphological differential diagnosis between occupational and "idiopathic" pulmonary fibroses]. / Histomorphologische Differentialdiagnose zwischen berufsbedingten und "idiopathischen" Lungenfibrosen.

Pulmonary fibroses are terminal stages of exposure to a whole series of very diverse noxae. Both occupational and nonoccupational causes must be distinguished. Finally, there is the large collective category "idiopathic" fibroses. In terms of their systematics, fibroses can be classified in five largegroups. The classification criteria are etiological when the causes are known, and morphological-descriptive in cases of idiopathic fibrosis. Occupational and "idiopathic" fibroses often cannot be distinguished in biopsy material because of their great histomorphological similarity. In such circumstances, the result of further analyses is crucial. For this reason, the possibility that an occupational pulmonary fibrosis is present must also be considered even in "idiopathic" pulmonary fibroses in order to arrange for further analyses such as BAL, ashing and energy-dispersive X-ray analysis to be performed.

[Spinach powder-induced exogenous allergic alveolitis]. / Spinatpulverinduzierte exogen-allergische Alveolitis.

A 51-year old woman developed hypersensitivity pneumonitis to spinach powder, which is used as a food dye. The diagnosis was confirmed by demonstration of IgG2-antibodies in the patient's serum to distinct bands of spinach extract by Western blotting. Furthermore an exposure test with the natural allergen was positive. Severe disease with fever, chills and dyspnoea developed after inhalation of native spinach powder. Arterial pO2 dropped significantly and pulmonary function tests showed severe restrictive impairment and reduction of diffusion capacity. Leucocyte count and the serum concentrations of the cytokines TNF alpha and IL6 and of the soluble IL2-receptor rose significantly in peripheral blood, whereas the concentration of neopterine did not change. 24 hours after exposure bronchoalveolar lavage showed an increase of neutrophils. In lung parenchyma mononuclear interstitial infiltrates and an epitheloid cell granuloma were seen.

Crohn's disease and sarcoidosis: systemic granulomatosis?

We report an unusual case of severe Crohn's disease with involvement of the lung. In 1993 at age 21 a male patient experienced a Helicobacter-negative duodenitis. A routine chest radiograph revealed spotted opacities in the right upper lobe without discomfort and normal pulmonary function except for a reduced diffusion capacity. Bronchoalveolar lavage showed mild lymphocytosis and biopsies from the macroscopically normal bronchi displayed non-caseating granulomas. In 1995 he had symptoms of peptic ulcer disease with a gastric outlet stenosis. He underwent Billroth I resection with only temporary improvement. Three months later the symptoms had recurred and a stenosing inflammatory process of the duodenum was seen on endoscopy suggesting Crohn's disease. A chest radiograph demonstrated infiltrations in parts of the left lung and bronchoalveolar lavage again revealed alveolar lymphocytosis (CD4/CD8 ratio 3.1). Both the gastrointestinal and pulmonary affections responded to corticosteroids but the duodenal stricture had to be resected. The association of Crohn's disease and pulmonary disorders is discussed.