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There is a supermassive black hole of mass 4 × 106solar masses at the centre of the Milky Way1,2. A large reservoir of hot (107kelvin) and cooler (102to 104kelvin) gas surrounds it within a few parsecs3. Although constraints on the amount of hot gas in the accretion zone of the black hole—that is, within 105Schwarzschild radii (0.04 parsecs)—have been provided by X-ray observations4–6, the mass in cooler gas has been unconstrained. One possible way this cooler gas could be detected is by its emission in hydrogen recombination spectral lines7,8. Here we report imaging of a 104-kelvin ionized gas disk within 2 × 104Schwarzschild radii, using the 1.3-millimetre recombination line H30α. This emission line is double-peaked, with full velocity linewidth of about 2,200 kilometres per second. The emission is centred on the radio source Sagittarius A*, but the redshifted side is displaced 0.11 arcsec (0.004 parsecs at a distance of 8 kiloparsecs) to the northeast and the blueshifted side is displaced a similar distance to the southwest. We interpret these observations in terms of a rotating disk of mass 10−5to 10−4solar masses and mean hydrogen density of about 105to 106per cubic centimetre, with the values being sensitive to the assumed geometry. The emission is stronger than expected, given the upper limit on the strength of the Brγ spectral line of hydrogen. We suggest that the H30α transition is enhanced by maser emission.

Accurate and timely identification of pulmonary disease has long been a great challenge in medicine. In most cases, the clinician cannot arrive at a definitive diagnosis via 1 modality alone; thus, multiple tools must be utilized to arrive at the most complete and accurate clinical conclusion. Bronchoalveolar lavage fluid is typically rich in cellular and noncellular constituents of the lower airways, providing insight into the immunologic and inflammatory state of the bronchoalveolar space. Despite the relative ease and safety of obtaining bronchoalveolar lavage fluid, the analysis of specific cell populations remains controversial. Lymphocyte subsets, including CD4 T-helper cells and CD8 cytotoxic T cells, have known roles in the immunopathology of various lung diseases. CD4/CD8 ratios are of little clinical utility when used alone; however, in combination with other variables, these markers may provide useful clinical information that may contribute to a more confident diagnosis, especially when sarcoidosis is the cause of the lung disorder. We propose that the expert clinician should not completely discard this potentially valuable tool.

Percutaneous dilatational tracheostomy can be performed blindly on the basis of the identification of landmarks alone or using fiberoptic bronchoscopy or ultrasonography to guide the procedure. There is controversy regarding the use of bronchoscopic guidance for the procedure. We have evaluated the literature to determine the utility of this practice.

Tissue engineering approaches using growth factor-functionalized acellular scaffolds to support and guide repair driven by endogenous cells are thought to require a careful balance between cell recruitment and growth factor release kinetics. The objective of this study was to identify a growth factor combination that accelerates progenitor cell migration into self-assembling peptide hydrogels in the context of cartilage defect repair. A novel 3D gel-to-gel migration assay enabled quantification of the chemotactic impact of platelet-derived growth factor-BB (PDGF-BB), heparin-binding insulin-like growth factor-1 (HB-IGF-1), and transforming growth factor-β1 (TGF-β1) on progenitor cells derived from subchondral bovine trabecular bone (bone-marrow progenitor cells, BM-PCs) encapsulated in the peptide hydrogel [KLDL]3. Only the combination of PDGF-BB and TGF-β1 stimulated significant migration of BM-PCs over a 4-day period, measured by confocal microscopy. Both PDGF-BB and TGF-β1 were slowly released from the gel, as measured using their 125I-labeled forms, and they remained significantly present in the gel at 4 days. In the context of augmenting microfracture surgery for cartilage repair, our strategy of delivering chemotactic and proanabolic growth factors in KLD may provide the necessary local stimulus to help increase defect cellularity, providing more cells to generate repair tissue.

Flexibilität sorgt für Selektivität: Die selektive Adsorption von CO2aus Gasgemischen mit N2, CH4und N2O in einem dynamischen porösen Koordinationspolymer (siehe Monomerstruktur) wurde durch ATR‐FTIR‐Spektroskopie, Gaschromatographie und Kleinwinkelröntgenstreuung untersucht. Alle drei Techniken bestätigen eine hoch selektive Adsorption von CO2aus CO2/CH4‐ und CO2/N2‐Gemischen bei 30 °C und keine Selektivität beim CO2/N2O‐System.

Flexibility provides selectivity: The selective adsorption of CO2from mixtures with N2, CH4, and N2O in a dynamic porous coordination polymer (see monomer structure) was evaluated by ATR‐FTIR spectroscopy, GC, and SANS. All three techniques indicate highly selective adsorption of CO2from CO2/CH4and CO2/N2mixtures at 30 °C, with no selectivity observed for the CO2/N2O system.

Stream flows and associated aquatic ecosystems have been altered in many streams and rivers as a result of human activity. Efforts to restore streams to more “normative” conditions are occurring thoughout the United States. The Nature Conservancy's Sustainable Waters program (2005) is actively supporting stream‐flow restoration at more than 300 sites throughout the country. The need for restoration has been further focused in many areas in response to endangered species listings for fish and other aquatic species. This further increases the value of adequate in‐stream flow during critical times for various aquatic species.

Type I lissencephaly is a central nervous system (CNS) malformation characterized by mental retardation and epilepsy. These clinical features suggest a deficit in inhibitory neurons may, in part, underlie the pathogenesis of this disorder. Mutations in, or deletions of, LIS1are the most commonly recognized genetic anomaly associated with type I lissencephaly. The pathogenesis of type I lissencephaly is believed to be a defect in radial neuronal migration, a process requiring LIS1. In contrast the inhibitory neurons migrate non-radially from the basal forebrain to the neocortex and hippocampus. Given that Lis1 is expressed in all neurons, we hypothesized that Lis1 also functions in non-radial migrating inhibitory neurons. To test this hypothesis we used a combination of in vivoand in vitrostudies with Lis1mutant mice and found non-radial cell migration is also affected. Our data indicate Lis1 is required for normal non-radial neural migration and that the Lis1 requirement is primarily cell autonomous, although a small cell non-autonomous effect could not be excluded. These data indicate inhibitory neuron migration is slowed but not absent, similar to that found for radial cell migration. We propose that the defect in non-radial cell migration is likely to contribute to the clinical phenotype observed in individuals with a LIS1mutation.

The diagnosis of systemic histoplasmosis may be delayed due to underlying pulmonary conditions in patients from an endemic area. An adolescent White male from the Midwestern United States with a history of moderate persistent asthma presented to the pulmonary clinic with a 10-day’s history of cough. The patient had no response to modifications of his asthma treatment regimen and proceeded to experience worsening symptoms, including pleuritic chest pain and dysphagia. Chest imaging revealed multiple pulmonary nodules, right mainstem bronchus narrowing, bilateral hilar adenopathy, and esophageal thickening. Ophthalmologic examination revealed an ocular “histo spot”, but the patient denied any ocular symptoms. Despite negative initial histoplasmosis antibody testing, the patient began oral itraconazole therapy for presumed histoplasmosis infection. Follow-up histoplasmosis antibody titers were positive, and the patient responded well to itraconazole. Disseminated histoplasmosis can have a wide range of presenting symptoms, which may delay its diagnosis among patients with pre-existing asthma.

• Despite growing numbers of frail elderly, physicians make housecalls infrequently. We surveyed 1000 primary care physicians from Virginia regarding their attitudes and knowledge about housecalls, and 389 completed questionnaires (response rate, 52%): 185 family physicians, 36 general practitioners, 101 general internists, and 63 subspecialists. Despite similar proportions of homebound patients and practice demographics, family physicians (69%) and general practitioners (63%) were significantly more likely than either internists (53%) or subspecialists (37%) to make routine housecalls. Although all four groups thought the fee was rarely a motivation, internists and subspecialists suggested larger increases. Also, internists and subspecialists were less likely than family physicians or general practitioners to increase housecalls with increased payment. Internists and subspecialists also were more likely than family physicians or general practitioners to report that housecalls were often unnecessary, not "enjoyable," "inefficient," and unimportant. While improved reimbursement may lead to increased housecalls by family physicians, future strategies should include efforts to change internists' attitudes.(Arch Intern Med. 1990;150:2333-2337)

Trimethoprim-sulfamethoxazole (TMP-SMX) or trimethoprim (TMP) alone was given on a random double-blind basis to 26 young women to treat urinary tract infections. Fecal and introital aerobic bacterial floras were identified at 1, 7, 14, and 42 days to analyze changes in these floras or development of resistance to TMP or TM-SMX. Neither TMP alone nor the TMP-SMX combination administered for 2 weeks selected a resistant fecal or introital flora. In the few individuals who had strains resistant to TMP or TMP-SMX before initiation of therapy, these organisms did not persist once therapy began. Both programs effectively cleared the introitus and rectal areas of Enterobacteriaceae. Concentrations of TMP adequate to inhibit the majority of Escherichia coli strains causing urinary tract infections were found in the vaginal secretions.

Piperacillin sodium, a semisynthetic penicillin that inhibits many Klebsiella and Pseudomonas aeruginosa organisms resistant to carbenicillin, was used to treat 41 episodes of infection in 35 patients. Infectious sites included lungs, urinary tract, and tissue, including peritonitis. Seven patients had bacteremia. Clinical and bacteriological cures were achieved in 85% of infections. Cure was achieved with piperacillin in patients infected with carbenicillin-resistant P aeruginosa and Klebsiella organisms. Adverse effects were minor and included rash in two patients. Serum levels were easily maintained above the inhibitory levels for susceptible organisms. Piperacillin was a safe, well-tolerated, and effective antimicrobial agent.(Arch Intern Med 1981;141:1447-1450)

Abstract: Objective:To evaluate factors associated with the frequency of house calls by primary care physicians. Design:A cross-sectional design with a self-administered mailed survey. Setting/participants:751 primary care physicians who care for Medicaid patients in Virginia. Results:Among 389 physician respondents (52%), regular house callers (n=216) were compared with occasional house callers (n=162). Among physician characteristics, specialty and practice duration were associated with house call frequency. Regular house callers also more often cited chronic illness (67% vs. 20%, p<0.01) and terminal illness (67% vs. 40%, p<0.01) as indications for house calls, compared with occasional house callers. Use of visiting nurses to substitute for physician house calls was less often considered appropriate by frequent house callers (7% vs. 24%, p<0.01), and regular house callers were less likely to report being “too busy” to make house calls (71% vs. 29%, p<0.01). Multivariate analysis confirmed the association of these attitudes with house call frequency. Conclusion:These data suggest that specific attitudes among primary care physicians are associated with house call frequency.

An improved preparation for cyclobutadienyliron tricarbonyl complexes from 3,4-carbonyldioxycyclobutenes has been developed. The development of the procedure revealed a number of the details of the reaction and the importance of the method used to prepare tetracarbonylferrate (-2) on subsequent reactions.

A single Ly-5 gene is known to generate a variety of transmembrane glycoprotein isoforms that distinguish various cell lineages and stages of differentiation within the hematopoietic developmental compartment of the mouse. Systems homologous to Ly-5 are known in rats and in humans. The complete exon-intron organization of the Ly-5 gene is described in this report. The Ly-5 gene occupies about 120 kilobases of chromosome 1 and comprises 34 exons, of which 32 (Ex-3 to Ex-34) are protein coding. Ex-1, Ex-2, and parts of Ex-3 and Ex-34 are untranslated. In all cDNA clones examined, either Ex-1 or Ex-2 was represented, but not both, implying that Ex-1 and Ex-2 in Ly-5 mRNA may be mutually exclusive. Primer extension and S1 nuclease protection mapping were used to identify initiation (cap) sites for transcription. The finding of putative cap sites for Ex-1 and Ex-2, and of corresponding TATA-like sequences, suggests the presence of two promoters. In both Ex-1+ and Ex-2+ cDNA clones the next exon is Ex-3, which has a translation-initiating codon. The intron between Ex-3 and Ex-4 is unusually long, about 50 kilobases. Evidence is given that Ex-5, like Ex-6 and Ex-7 (studied previously), is another alternative exon that is selectively programmed, alone or together with Ex-6 or Ex-7 or both, to generate actual or potential Ly-5 isoforms by alternative splicing.

There is an unusual but apparently infrequent type of intrathoracic growth occurring in the apical region, yet found with sufficient frequency in my experience to warrant a collective report of the cases encountered. The neoplastic condition is unusual for the reason that it produces referred nerve phenomena in the upper extremity which may be very misleading to the clinician and roentgenologist in their search for the cause; and when to these manifestations are added certain cervical sympathetic phenomena, the symptomatology of spinal cord tumor is closely simulated, especially in the absence of any apparent extraspinal etiologic factor. I have been fortunate enough to learn the exact nature of these growths from careful pathologic studies in two cases, and in all four cases there has been a most satisfactory correlation of clinical and roentgenologic data.In three of the four cases, an early diagnosis of the condition present was missed because

The upper respiratory tract, from the nasopharynx to the carina, has recently become a very important field for roentgenologic diagnosis. The most important factor in diagnosis is a careful study of the soft structures during an examination of the neck. This includes fluoroscopic observations of the movements or changes in lumen of the various portions of the tract during respiration, speech and swallowing, and the making of roentgenograms for records. In all instances the chest should be included, and especially in infants and young children.It seems strange that, following Scheier's studies of speech mechanism in 19091 and of the swallowing act in 1911,2 the publication of Thost's beautiful atlas3 recording his observations on the normal and pathologic larynx in 1913 and Iglauer's4 pioneer work in this country in 1914, the subject of diagnosis of diseases of the upper respiratory tract by roentgen methods should have

PART I. Before reporting the technical aspects of the method of treatment which we have recently practiced it may be well to consider very briefly those aspects of the pathology of leukemia which bear on the matter of the topical treatment with agents such as the x-rays and also to review the facts that have become known regarding the probable effects of the x-rays on the tissues in this disease. PATHOLOGY OF LEUKEMIA. The gross lesions observed in leukemia, whether of the lymphatic or lienomedullary form, are much the same. There is found an infiltration of a grayish white character in the spleen, bone marrow or lymph nodes, or in all of these structures, and not infrequently a similar change in the liver, kidneys and other glandular organs. In the so-called lymphatic form, these changes are especially pronounced in the lymphatic nodes, and macroscopically may be confined to these

Radiology occupies rather a unique position as a subject for teaching to undergraduate medical students. It is a new medical specialty. Its diagnostic and therapeutic applications have grown at a tremendous rate and have become unusually widespread. While it is more or less intimately concerned in every branch of medicine, its development has been left largely in the hands of a comparatively few medical men, assisted in a great measure by physicists and manufacturers of equipment. Its development and its position as a specialty have been taken largely for granted by the greater part of the medical profession. Comparatively few students or recent graduates expect to take it up as a specialty or even to practice it directly in a smaller way, although it must serve all of them. For these reasons, little earnest thought has been given to radiology from the standpoint of undergraduate teaching, aside from the desire

The discovery of the therapeutic properties of x-rays was the outcome of the observation of damage to tissues as the result of prolonged exposure. Any therapeutic agent that is dangerous to tissues or to life must be administered according to standardized dosage, which must be determined by experience and animal experimentation. Before the dangerous properties of x-rays were known, some of the early patients were the victims. Steps were then taken to attempt to prescribe a safe limit for irradiation, but several years elapsed before this could be accomplished in an entirely satisfactory manner. The operator of the equipment was exposed to the radiation to a less amount than the patient, but continually, and the early roentgenologists, technicians, and even manufacturers became the victims of damage to their skin which was later found to be irreparable. The chronic and irritated ulcerations became the seat of cancerous degenerations in many instances,

Little has been added to our knowledge of the etiology or pathology of leukemia and Hodgkin's disease during the last few years. Some details regarding the diagnosis have been established and in the case of Hodgkin's disease the clinical differentiation from certain conditions presenting superficial resemblances has been made possible. So far as the ultimate causes and nature of these diseases are concerned, we remain in the same ignorance as formerly. The tendency among writers has, it is true, been more and more commonly manifested in the direction of regarding both as close kindred of the new growths, a view which we have held for a long time and on which in a large measure our methods of using the x-rays in the treatment are based. In our former discussion of the subject1 we called attention to the fact that so far as leukemia is concerned all recent investigations

This work was undertaken as the result of the observations of one of us (Pancoast1) on the gastro-intestinal motility of a patient who had a hypodermic of morphin several hours before the Roentgen studies were made. There was found not only an hour-glass constriction of the stomach, but also a striking retardation of the motility of the small intestine. Control studies on this patient at a later date, and when freed from the influence of morphin, revealed no such abnormalities.The earliest investigations in which the Roentgen rays were utilized in the study of the action of opium and its derivatives on the gastro-intestinal tract were those in which animals, especially dogs and cats, were utilized. These studies frequently revealed, not only a retention of the bismuth meal in the esophagus for a period of one-half hour, but also a retention, even for hours, in the fundus and not

In view of the more recent pathologic and histologic studies, added clinical experience and a much better knowledge of the condition, physicians are now at a loss to define pneumonoconiosis and its most frequent industrial form of silicosis in any simple terms such as have been applied in the past. The general term of pneumonoconiosis must still be adhered to because other dusts than silica are capable of producing definite histologic changes in the lung structure, as coal dust, certain silicates and possibly many others, but the effects of which require further study. It is the prevailing impression that pulmonary fibrosis is the essential and characteristic feature of pneumonoconiosis in general, but in reality this is the terminal effect. Probably certain intermediate changes are of very considerable importance except in the way of the terminal disability. In discussing pneumonoconiosis, we are giving consideration to only those histologic changes which are

Medicine is not and cannot be an exact science because of the complexity of the human element involved. Roentgenology is the youngest branch of the specialties and is a study of living pathology. Even pathology is subject to many changes through experience, progress in investigation and study. This is one of the factors concerned in changes in roentgenology, and presumably for its betterment, through greater exactitude, further investigations, added experience and the acknowledgment of and correction of mistakes. In 1924, when a group of roentgenologists were on trial for possible acceptance as a new section in the American Medical Association, I presented a paper1 before the Section on Miscellaneous Topics, in which were reported three cases of what seemed to be a new entity among intrathoracic tumors. I have selected this subject again for the chairman's address as one slight means of showing that roentgenologists are genuinely alive to

Achondroplasia, a chondral dystrophy, has been known under the synonyms of "chondrodystropia fetalis," "fetal rickets," "fetal cretinism" and "micromelia." Sommering first described it in 1791. Achondroplasia is of great antiquity. Pernet draws attention to the fact that at the British Museum there are a number of glazed earthenware images, which are unquestionably models of achondroplastic individuals. They were represented as dwarfs with big heads, crooked legs, very long arms, etc.The pathology was not understood until Parrot differentiated achondroplasia from syphilis and rickets in 1878.Innumerable writers have considered the subject since that time. Schirmer1 gives 110 references. To this article and to the earlier article of Porak published in 1889, the reader is referred for a full exposition of the entire subject. It would appear to us that Porak's article and Schirmer's are the ones on which the entire

Sufficient evidence is furnished by the excellent work of Braasch and many others to establish without question of doubt the value of pyelography in the diagnosis of surgical diseases of the kidney and ureter. Additional testimony based on our own experience would mean merely a repetition of what has already been stated. Another phase of the subject, which is of equal importance and forms the theme of this paper, is the consideration of the harmful results that may follow collargol injection, its indications and limitations.When we first began the use of pyelography, we shared the opinion of others that the injection of collargol into the renal pelvis was free from danger and employed it routinely in all cases presenting symptoms which might be due to renal pathologic conditions. In the course of time we became convinced of the error of such a procedure. With increasing knowledge acquired from our

In reviewing the literature on diaphragmatic hernia, it may be noted that the condition was discovered only seven times in 25,000 roentgenologic examinations, according to the separate reports of Beclere,1 MacMillan,2 and Rendich.3 The Mayo Clinic records finding twenty cases up to July, 1924, or one in about every 18,000 patients examined. According to Carman,4 fifteen of these were found in the years 1923 and 1924. Richards5 has tabulated 137 cases taken from the literature from 1900 to 1923. These were all nontraumatic and of the esophageal variety. It is worthy of note that up until 1923 only forty-seven cases had been diagnosed during life.While these figures would create the impression that the condition is rare, this is not the case. The more general employment of the roentgen ray with its recent advances in diagnosis makes it apparent that diaphragmatic hernia has frequently been overlooked in the past. Morrison,6

Much has been written during the last ten years on the roentgen-ray examination of the appendix. The views expressed by the various writers in this time, excluding a certain amount of overenthusiasm, have differed only in minor details and in the exact dependence to be placed on some of the observations made concerning pathologic conditions of this structure and of the surrounding organs. The value of the roentgenologic examination in connection with appendicitis may be discussed under the following heads: (1) congenital anomalies in position; (2) data obtainable from observation of the visualized appendix; (3) abnormal appearances in other structures suggesting appendiceal origin when the appendix is not visualized; (4) the finding of some other condition than appendicitis to account for the symptomatology; (5) the finding of some other condition accompanying appendicitis and requiring further surgical exploration, and the exclusion of any other surgical condition than a diseased appendix, thereby

The article discusses on the artistic profile and the background of the paintings of Brice Marden. It states that Marden usually starts a painting with a thought of a certain quality that he has found elsewhere, whether in other artwork, in a landscape, in a photograph, or in a relationship. It is considered that his work since 1965 consists of one, two, and finally three-panel paintings.

As utilization of renewable energy sources continues to expand, the need for new grid energy storage technologies such as redox flow batteries (RFBs) will be vital. Ultimately, the energy density of a RFB will be dependent on the redox potentials of the respective electrolytes, their solubility, and the number of electrons stored per molecule. With prior literature reports demonstrating the propensity of nitrogen-containing heterocycles to undergo multielectron reduction at low potentials, we focused on the development of a novel electrolyte scaffold based upon a 2,2′-bipyrimidine skeleton. This scaffold is capable of storing two electrons per molecule while also exhibiting a low (∼−2.0 V vs Fc/Fc+) reduction potential. A library of 24 potential bipyrimidine anolytes were synthesized and systematically evaluated to unveil structure–function relationships through computational evaluation. Through analysis of these relationships, it was unveiled that steric interactions disrupting the planarity of the system in the reduced state could be responsible for higher levels of degradation in certain anolytes. The major decomposition pathway was ultimately determined to be protonation of the dianion by solvent, which could be reversed by electrochemical or chemical oxidation. To validate the hypothesis of strain-induced decomposition, two new electrolytes with minimal steric encumbrance were synthesized, evaluated, and found to indeed exhibit higher stability than their sterically hindered counterparts.

AbstractIn an acute-care general hospital, 114 telephones, intercoms, dictaphones, and bedpan flusher handles were sampled in patient-care areas for type of bacterial contamination. Nine of these (7%) demonstrated potentially pathogenic bacteria including Klebsiella, Enterobacter, Pseudomonas and Aeromonas. Inanimate, environmental, staff hand-contact objects were only lightly contaminated, did not represent a significant reservoir of gram-negative organisms, and therefore, would be unlikely to be a vehicle of transmission of gram-negative bacteria from the hands of one staff member to another under routine circumstances. Surveillance and disinfection of telephones and related hand-contact items in the hospital appear unnecessary.

This report is based on an analysis of twenty-four cases of carcinoma of the ovary which have been referred to the roentgen-ray laboratory of the University of Pennsylvania Hospital for treatment. In all, the diagnosis has been proved by operation, and each patient has received at least one complete series of treatments.CONDITION OF PATIENTSPreceding irradiation, the following operations had been performed: exploratory, six; bilateral salpingo-oophorectomy, seven; bilateral salpingo-oophorectomy and hysterectomy, eight, and unilateral salpingo-oophorectomy, three.With only one exception (ruptured carcinomatous cyst), visible peritoneal metastases were present at the time of the operation; complete removal of the carcinomatous ovary was impossible, or late recurrence had followed operation. Irradiation was given in twenty cases from one to three months after operation, while in four, intervals of six months, seven months, one and one-half years and seven years, respectively, had elapsed between operation and recurrence.Papillary carcinoma was present in

At the present time, no single method of treatment is adaptable to all cases of malignant disease. Of the many procedures now employed, surgery has the widest adaptation in cases in which the growth is accessible and can be completely eradicated, with the possible exception of superficial epitheliomas in certain localities. In many instances, the lesions must be attacked by a combination of several of the procedures now at our command. Radium and Roentgen rays, while by no means the only agents that may be employed in cases not suitable for operative procedures, have probably the widest field of application next to surgery. When large surfaces must be exposed, as in the treatment of mammary carcinoma with its many harbors of metastasis, and when intensive deep cross-fire radiation is essential, as in the treatment of mediastinal, abdominal or pelvic tumors, Roentgen therapy is the method of choice between the two