Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 10 de 10
Filter
Add more filters










Publication year range
1.
Nature ; 592(7853): 237-241, 2021 04.
Article in English | MEDLINE | ID: mdl-33828316

ABSTRACT

Magma viscosity strongly controls the style (for example, explosive versus effusive) of a volcanic eruption and thus its hazard potential, but can only be measured during or after an eruption. The identification of precursors indicative of magma viscosity would enable forecasting of the eruption style and the scale of associated hazards1. The unanticipated May 2018 rift intrusion and eruption of Kilauea Volcano, Hawai'i2 displayed exceptional chemical and thermal variability in erupted lavas, leading to unpredictable effusion rates and explosivity. Here, using an integrated analysis of seismicity and magma rheology, we show that the orientation of fault-plane solutions (which indicate a fault's orientation and sense of movement) for earthquakes preceding and accompanying the 2018 eruption indicate a 90-degree local stress-field rotation from background, a phenomenon previously observed only at high-viscosity eruptions3, and never before at Kilauea4-8. Experimentally obtained viscosities for 2018 products and earlier lavas from the Pu'u 'O'o vents tightly constrain the viscosity threshold required for local stress-field reorientation. We argue that rotated fault-plane solutions in earthquake swarms at Kilauea and other volcanoes worldwide provide an early indication that unrest involves magma of heightened viscosity, and thus real-time monitoring of the orientations of fault-plane solutions could provide critical information about the style of an impending eruption. Furthermore, our results provide insight into the fundamental nature of coupled failure and flow in complex multiphase systems.

2.
Science ; 366(6470)2019 12 06.
Article in English | MEDLINE | ID: mdl-31806788

ABSTRACT

Lava flows present a recurring threat to communities on active volcanoes, and volumetric eruption rate is one of the primary factors controlling flow behavior and hazard. The time scales and driving forces of eruption rate variability, however, remain poorly understood. In 2018, a highly destructive eruption occurred on the lower flank of Kilauea Volcano, Hawai'i, where the primary vent exhibited substantial cyclic eruption rates on both short (minutes) and long (tens of hours) time scales. We used multiparameter data to show that the short cycles were driven by shallow outgassing, whereas longer cycles were pressure-driven surges in magma supply triggered by summit caldera collapse events 40 kilometers upslope. The results provide a clear link between eruption rate fluctuations and their driving processes in the magmatic system.

3.
Appl Phys B ; 125(211)2019 Oct 21.
Article in English | MEDLINE | ID: mdl-31920221

ABSTRACT

We present the design of a portable version of our miniaturized laser heterodyne radiometer (mini-LHR) that simultaneously measures methane (CH4) and carbon dioxide (CO2) in the atmospheric column. The mini-LHR fits on a backpack frame, operates autonomously, and requires no infrastructure because it is powered by batteries charged by a folding 30 W solar panel. Similar to our earlier instruments, the mini-LHR is a passive laser heterodyne radiometer that operates by collecting sunlight that has undergone absorption by CH4 and CO2. Within the mini-LHR, sunlight is mixed with light from a distributive feedback (DFB) laser centered at approximately 1.64 µm where both gases have absorption features. The laser scans across these absorption features roughly every minute and the resulting beat signal is collected in the radio frequency (RF). Scans are averaged into half hour and hour data products and analyzed using the Planetary Spectrum Generator (PSG) retrieval to extract column mole fractions. Instrument performance is demonstrated through two deployments at significantly different sites in interior Alaska and Hawaii. The resolving power (λ/∆λ) is greater than 500,000 at 1.64 µm with precisions of better than 20 ppb and 1 ppm for CH4 and CO2, respectively. Because mini-LHR instruments are portable and can be co-located, they can be used to characterize bias between larger, stationary, column observing instruments. In addition, mini-LHRs can be deployed quickly to respond to transient events such as methane leaks or can be used for field studies targeting geographical regions.

4.
Science ; 363(6425): 367-374, 2019 01 25.
Article in English | MEDLINE | ID: mdl-30538164

ABSTRACT

In 2018, Kilauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'O'o vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 kilometers. A 4 May earthquake [moment magnitude (M w) 6.9] produced ~5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to M w 4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent-about 0.8 cubic kilometers. Careful historical observation and monitoring of Kilauea enabled successful forecasting of hazardous events.

5.
South Med J ; 93(12): 1201-4, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11142457
6.
Nihon Hinyokika Gakkai Zasshi ; 91(12): 700-7, 2000 Dec.
Article in Japanese | MEDLINE | ID: mdl-11201130

ABSTRACT

INTRODUCTION AND OBJECTIVE: The tumor biology of renal cell carcinoma (RCC) remains poorly understood and the prognosis of which is unpredictable. To define an optimal follow-up protocol in nonmetastatic RCC, tumor recurrences and the clinical course were assessed in the patients who had undergone nephrectomy. PATIENTS AND METHODS: Between March 1972 to July 1999, 265 patients with PT1-3N0 (Nx) M 0 RCC underwent radical or partial nephrectomy. Clinicopathological variables were compares with the time of the first recurrence, site of metastasis and reason for diagnosis. RESULTS: In July 1999, the median (range) follow-up for the surviving patients was 50 (1-244) months. Metastases were diagnosed in 45 of the 265 patients (17%). Sixty percent of the patients had their metastases diagnosed within 3 years and 87% by 6 years. The incidence and the mean time to first diagnosis of recurrence were 9.0% and 43.6 months for pT1, 32.4% and 39.6 months for pT2, and 32.7% and 25.0 months for pT3. Metastatic sites and the mean time of diagnosis were 40.6 months in lung (46.7%), 26.1 months in bone (17.8%), 18.6 months in retroperitoneal organs (11.1%), 38.0 months in liver (6.7%), 51.0 months in thyroid gland (4.4%) and 31.0 months in brain (2.2%). Most recurrence in lung, retroperitoneal organs and liver were incidentally diagnosed, whereas recurrences in bone, thyroid gland and brain had some symptoms associated with metastases. Incidence of lung metastasis in pT1 (9 patients, 56%) and pT2 (6, 55%) was greater than that in PT3 (6, 33%). In contrast, incidence of abdominal metastasis (retroperitoneal organs and the liver) in pT3 (4 patients, 33%) was grater than pT1 (2, 12%) and PT2 (1, 16%). CONCLUSIONS: The results indicate that the risk of tumor progression and site of metastasis seemed to depend on original TNM stage. Therefore stage specific postoperative follow-up protocol should be considered. The yearly follow-up may suffice for pT1a patients after surgery. For pT1b and pT2 patients, the follow-up should be intense during the first 3 years by a routine chest X-ray. For pT3 patients, the follow-up during the first 2 years may be important. Particularly, considering the high incidence of abdominal metastasis in these patients, examination by CT scan is recommended every 6 months in the first 2 years. No need for bone scintigraphy and brain CT was indicated for asymptomatic patients.


Subject(s)
Carcinoma, Renal Cell/epidemiology , Kidney Neoplasms/epidemiology , Carcinoma, Renal Cell/etiology , Carcinoma, Renal Cell/surgery , Clinical Protocols , Female , Follow-Up Studies , Humans , Kidney Neoplasms/etiology , Kidney Neoplasms/surgery , Male , Recurrence
7.
Obstet Gynecol ; 91(5 Pt 2): 846-8, 1998 May.
Article in English | MEDLINE | ID: mdl-9572186

ABSTRACT

BACKGROUND: The decision to recommend removal or conservation of a normal ovary and uterus in a young woman with advanced ovarian cancer is difficult and controversial. CASE: A 21-year-old patient with a large-cell variant of small-cell carcinoma of the ovary stage IIIc underwent optimal debulking surgery with preservation of the normal appearing uterus and opposite adnexa followed by aggressive multi-agent chemotherapy. She is menstruating normally and is free of disease, more than 2 years since completion of chemotherapy. CONCLUSION: In selected cases, conservation of the uninvolved ovary and uterus in patients with advanced-stage, small-cell carcinoma of the ovary may not compromise survival.


Subject(s)
Carcinoma, Small Cell/surgery , Ovarian Neoplasms/surgery , Adult , Carcinoma, Small Cell/pathology , Carcinoma, Small Cell/secondary , Female , Humans , Ovarian Neoplasms/pathology
8.
Pathol Res Pract ; 186(2): 212-22, 1990 Apr.
Article in English | MEDLINE | ID: mdl-2188235

ABSTRACT

Fourty-six bronchial carcinoids, twelve tumourlets and twenty areas of neuroendocrine cell dysplasia (NED) were immunohistochemically evaluated for various neuroendocrine markers, S-100 protein (S-100), myelin basic protein, intermediate filaments, actin, Leu-7 and several neurohormonal polypeptides. Eighteen of the bronchial carcinoids (39.1%) showed a biphasic cell pattern, with abundant stellate-shaped S-100 positive cells (SC). SC were not reactive for chromogranin A, myelin basic protein, cytokeratins, neurofilaments, glial fibrillary acidic protein or actin, and were only occasionally weakly positive for vimentin. SC were not detected in the tumourlets nor in the NED observed. For comparison a group of other neuroendocrine tumours (11 gastrointestinal carcinoids, 4 pheochromocytomas and 4 paragangliomas) were immunostained for S-100, chromogranin A and actin. SC similar to the ones detected in the bronchial carcinoids could be detected in appendiceal carcinoids, paragangliomas and in two out of four pheochromocytomas. Our present data are in keeping with a Schwannian/sustentacular nature of SC rather than that of a histiocytic or myoepithelial nature. We suggest that SC-rich bronchial carcinoids are biphasic tumours, which could be designed "paraganglioid" bronchial carcinoids. The relationship between SC-rich bronchial carcinoids and tumourlets/NED is a matter of further investigation: SC-rich bronchial carcinoids may either differentiate in a biphasic pattern during tumoural growth or may not be histogenetically related to tumourlets.


Subject(s)
Bronchial Neoplasms/pathology , Carcinoid Tumor/pathology , Gastrointestinal Neoplasms/pathology , Paraganglioma/pathology , Pheochromocytoma/pathology , S100 Proteins/analysis , Adrenal Gland Neoplasms/pathology , Bronchial Neoplasms/analysis , Carcinoid Tumor/analysis , Humans , Immunoenzyme Techniques
9.
Oral Surg Oral Med Oral Pathol ; 67(6): 725-30, 1989 Jun.
Article in English | MEDLINE | ID: mdl-2662107

ABSTRACT

We have identified 14 cases that over the last 40 years have been reported under a series of names, most commonly granular cell ameloblastic fibroma. An additional case in the mandibular premolar region of a 45-year-old woman is described. The tumor was conservatively removed and 4 years later shows no evidence of recurrence. On the basis of our examination of the clinical and histologic features of this lesion and a comparison with the previous cases, we agree with the recent suggestion that the tumor should be designated as a central odontogenic fibroma, granular cell variant. By means of S-100 protein immunostaining techniques, the granular cells in this lesion were compared with the granular cell population in a granular cell tumor (myoblastoma) and the mesenchymal component of an ameloblastic fibroma. The results reveal a lack of S-100 protein reactivity in the granular cells of the central odontogenic fibroma and suggest an origin of those cells different from the origin of cells in a granular cell tumor.


Subject(s)
Mandibular Neoplasms/pathology , Odontogenic Tumors/pathology , Diagnosis, Differential , Epithelium/pathology , Female , Fibroma/pathology , Follow-Up Studies , Humans , Immunohistochemistry , Middle Aged , S100 Proteins
10.
Endocrinology ; 115(1): 255-60, 1984 Jul.
Article in English | MEDLINE | ID: mdl-6539669

ABSTRACT

When grouped, adult female mice excrete in their urine a chemosignal that delays sexual maturation of young females. This effect does not occur if the adult females have been adrenalectomized. In this report we test whether hormone replacement therapy affects the production and/or excretion of this chemosignal in adrenalectomized females. Injections of two glucocorticoids, corticosterone and hydrocortisone acetate, restored the delay chemosignal in excreted urine from grouped females. In subsequent dose-response experiments, we determined that daily injections of at least 125 micrograms corticosterone or 80 micrograms hydrocortisone acetate were needed to bring about the reappearance of the maturation-delaying substance in the urine of grouped adrenalectomized females. Injections of varying doses of a mineralcorticoid, deoxycorticosterone, did not produce restoration of the delay chemosignal in excreted urine from grouped females. Two additional tests revealed that injections of either glucocorticoid would restore the puberty-delaying activity to the bladder urine of both grouped and singly caged adrenalectomized females.


Subject(s)
Adrenalectomy , Corticosterone/pharmacology , Hydrocortisone/analogs & derivatives , Sexual Maturation , Animals , Dose-Response Relationship, Drug , Environment , Estrus , Female , Hydrocortisone/pharmacology , Mice , Mice, Inbred ICR , Pregnancy
SELECTION OF CITATIONS
SEARCH DETAIL
...