Synchronous crop failures and climate-forced production variability.

Large-scale modes of climate variability can force widespread crop yield anomalies and are therefore often presented as a risk to food security. We quantify how modes of climate variability contribute to crop production variance. We find that the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), tropical Atlantic variability (TAV), and the North Atlantic Oscillation (NAO) together account for 18, 7, and 6% of globally aggregated maize, soybean, and wheat production variability, respectively. The lower fractions of global-scale soybean and wheat production variability result from substantial but offsetting climate-forced production anomalies. All climate modes are important in at least one region studied. In 1983, ENSO, the only mode capable of forcing globally synchronous crop failures, was responsible for the largest synchronous crop failure in the modern historical record. Our results provide the basis for monitoring, and potentially predicting, simultaneous crop failures.

Closing of the Indonesian seaway as a precursor to east African aridification around 3-4 million years ago.

Global climate change around 3-4 Myr ago is thought to have influenced the evolution of hominids, via the aridification of Africa, and may have been the precursor to Pleistocene glaciation about 2.75 Myr ago. Most explanations of these climatic events involve changes in circulation of the North Atlantic Ocean due to the closing of the Isthmus of Panama. Here we suggest, instead, that closure of the Indonesian seaway 3-4 Myr ago could be responsible for these climate changes, in particular the aridification of Africa. We use simple theory and results from an ocean circulation model to show that the northward displacement of New Guinea, about 5 Myr ago, may have switched the source of flow through Indonesia-from warm South Pacific to relatively cold North Pacific waters. This would have decreased sea surface temperatures in the Indian Ocean, leading to reduced rainfall over eastern Africa. We further suggest that the changes in the equatorial Pacific may have reduced atmospheric heat transport from the tropics to higher latitudes, stimulating global cooling and the eventual growth of ice sheets.

CLIMATE VARIABILITY: Enhanced: Do the Tropics Rule?

Climate is not the same from one decade to the next, but as Cane and Evans explain in their Perspective, the mechanisms and even the patterns of decadal climate change are not well understood. The proxy climate record reported by Linsley et al. is an example of the kind of highly resolved records required from across the world to understand climate on these time scales.

Enhancement of calcium cycling by atrial sarcoplasmic reticulum after cardiopulmonary bypass and cardioplegia during open heart surgery.

We studied myocardial Ca2+ cycling during cardiopulmonary bypass and cold-blood cardioplegia (CPB/CBC) in patients with coronary heart disease undergoing coronary artery bypass grafting. Right atrial biopsies were taken from 13 patients before and after CPB/CBC: after pericardiotomy, immediately after aortic cross-clamp removal, and following termination of CPB/CBC. Changes in ionized Ca2+ concentration (nM) were monitored with indo 1 during Ca2+ uptake and Ca2+ release by sarcoplasmic reticulum in a medium containing 1% homogenized myocardium. Ryanodine inhibition was used to estimate Ca2+ release channel activity. With CPB/CBC, the initial Ca2+ concentration of reaction media increased 33%, (962 +/- 150 to 1262 +/- 106 nM; mean +/- SD). Ca2+ cycling increased asymmetrically, 108% for Ca2+ uptake (3.91 +/- 1.32 to 8.15 +/- 3.17 nM/s), 197% for Ca2+ release (0.90 +/- 0.80 to 2.73 +/- 1.13 nM/s), and 68% for the ratio of Ca(2+)-release to Ca(2+)-uptake activities (0.22 +/- 0.14 to 0.37 +/- 0.13). The dissociation constant of the Ca2+ pump for Ca2+ was unaltered by CPB/CBC (289 +/- 76 nM). During the time period that was studied post-bypass, Ca(2+)-pump activity remained increased, although the Ca(2+)-channel activity returned to pre-bypass values (all p < 0.05). We conclude that CPB/CBC produces increased myocardial Ca2+ load, twofold increased Ca2+ uptake, and threefold increased Ca2+ release by sarcoplasmic reticulum.

Paraganglioma of the interatrial septum.

The case of a patient undergoing successful resection of an interatrial septal paraganglioma is presented. The diagnosis of an interatrial mass was established preoperatively by echocardiography, ultrafast cine computed tomographic scan, and cardiac catheterization. The tumor was excised in total, and the interatrial septum and the roof of the left atrium were reconstructed using a bovine pericardial patch.

CABG in octogenarians: early and late events and actuarial survival in comparison with a matched population.

BACKGROUND: With important demographic changes in cardiac surgical practice, more older patients are undergoing complex cardiac operations. Controversy exists as to whether the expenditure of healthcare resources on the growing elderly populations represents an effective approach in maintaining a meaningful quality of life. METHODS: From January 1982 through April 1991, 121 consecutive octogenarians underwent a surgical procedure that included coronary artery bypass grafting. Retrospective review of patient medical records was performed; follow-up information was obtained via telephone contact with the patient, the patient's family, or the patient's physician. RESULTS: There were 67 men (55%) and 54 women (45%). Mean age was 82.1 years (range, 80 to 89 years). Sixty-nine percent of the patients were having class III or IV symptoms. There were 11 hospital deaths (9.1%); risk factors included longer cardiopulmonary bypass time (p = 0.01), higher preoperative left ventricular end-diastolic pressure (p = 0.02), advanced age (p = 0.05), history of renal disease (p = 0.02), and myocardial infarction (p = 0.04). Late death occurred in 34 patients (30.9%) at a mean of 27 months postoperatively; univariate risk factors included chronic obstructive pulmonary disease (p = 0.009), higher left-ventricular end-diastolic pressure (p = 0.03), and recent myocardial infarction (p = 0.03). Actuarial survival, including hospital death, was 32.8% at 80 months, compared with 37.6% for an age; sex; and race-matched population (p > 0.3). Most late survivors (84%) were in New York Heart Association class I or II. CONCLUSIONS: We conclude that coronary artery bypass grafting can be performed in octogenarians with an acceptable, although increased risk. Hospital survivors have a good late functional status but are at risk for pulmonary and other atherosclerosis-related events, which impair overall survival.

An Improved Procedure for EI Nino Forecasting: Implications for Predictability.

A coupled ocean-atmosphere data assimilation procedure yields improved forecasts of El Niño for the 1980s compared with previous forecasting procedures. As in earlier forecasts with the same model, no oceanic data were used, and only wind information was assimilated. The improvement is attributed to the explicit consideration of air-sea interaction in the initialization. These results suggest that EI Niño is more predictable than previously estimated, but that predictability may vary on decadal or longer time scales. This procedure also eliminates the well-known spring barrier to EI Niño prediction, which implies that it may not be intrinsic to the real climate system.

Heat shock protein (HSP 72) expression in patients undergoing cardiac operations.

The major mammalian stress-inducible protein, heat shock protein 72, protects cells from certain stresses and rapidly accumulates in cells after ischemia. Heat shock protein 72 is rapidly synthesized in the myocardium of various species in response to ischemia, but it has not been investigated in human heart. To determine if heat shock protein 72 accumulated in the ischemic myocardium of patients undergoing cardiac operations, we obtained sequential right atrial biopsy specimens from 12 patients undergoing repair at three intervals: before bypass, after reperfusion, and after bypass. Immunoblot analysis for heat shock protein 72 demonstrated a high expression in the human heart compared with other mammalian hearts, p (Binomial) = 0.01. Compared with before bypass, heat shock protein 72 contents after reperfusion and after bypass were 98.2% +/- 8.9%, p (signed-rank) = 0.65, and 87.6% +/- 17.1%, p (signed-rank) = 0.28, respectively. Although heat shock protein 72 concentration was unchanged in hearts after reperfusion and after bypass, the initial prebypass level of heat shock protein 72 was high. The high heat shock protein 72 level detected in human hearts may reflect preoperative disease and drug therapy, or inherently high levels may be usual in the human myocardium. These findings indicate that the myocardium of patients undergoing cardiac operations contains relatively high concentrations of heat shock protein 72, which are not increased during the surgical procedure.

Elective reoperation for a strut fracture in a Björk-Shiley convexo-concave mitral valve.

A 71-year-old asymptomatic man who had previously undergone mitral valve replacement with a 31-mm Björk-Shiley 60-degree convexo-concave valve was evaluated noninvasively and found to have a single leg outlet strut separation. Elective valve explantation was performed, and valve testing confirmed that a strut separation was indeed present. Diagnosis and early reoperation to replace a fractured prosthesis may improve patient survival.

El nino chaos: overlapping of resonances between the seasonal cycle and the pacific ocean-atmosphere oscillator.

The El Niño-Southern Oscillation (ENSO) cycle is modeled as a low-order chaotic process driven by the seasonal cycle. A simple model suggests that the equatorial Pacific ocean-atmosphere oscillator can go into nonlinear resonance with the seasonal cycle and that with strong enough coupling between the ocean and the atmosphere, the system may become chaotic as a result of irregular jumping of the ocean-atmosphere system among different nonlinear resonances. An analysis of a time series from an ENSO prediction model is consistent with the low-order chaos mechanism.

Transiently evoked otoacoustic emissions in patients with cerebellopontine angle tumors.

Transiently evoked otoacoustic emissions (TEOAE) are generally present in ears with normal hearing, but absent in ears with cochlear hearing losses greater than 25-30 dB; they have been demonstrated previously in a few ears with retrocochlear hearing losses greater than 30 dB across the frequency range 0.25-8 kHz. To assess the potential of TEOAEs in the diagnosis of retrocochlear hearing losses, measurements were made in 45 patients with retrocochler disorder attributable to confirmed cerebellopontine angle (CPA) tumors. Transiently evoked OAEs elicited by click stimuli were recordable in 21 (47%) of the ears with tumor. Nine of these had normal hearing at two or more octave frequencies across the range 0.5-4 kHz and so might be expected to have TEOAEs regardless of the type of disorder. The other 12 ears had recordable TEOAEs despite hearing threshold levels greater than 25 dB between 0.5 and 4 kHz. The absence of TEOAEs in the remaining 24 ears (53%) indicated a significant outer hair cell component to the hearing loss. Neither age nor sex were significant factors in the occurrence of TEOAEs. The TEOAE test gives useful differential diagnostic information when emissions are recorded in ears having hearing threshold levels greater than 25 dB at all frequencies. In such ears there is relatively normal cochlear function at the level of the outer hair cells, at least at some frequencies, and hence, by inference, there must be a retrocochlear disorder.

The feasibility of using oto-acoustic emissions to monitor cochlear function during acoustic neuroma surgery.

The feasibility of using evoked oto-acoustic emission (EOAE) measurement for intra-operative monitoring of cochlear function was assessed during removal of an acoustic neuroma in a 53-year-old woman with normal hearing on the operated side prior to surgery. The high level of noise in the operating theatre was the only material problem encountered and this was not sufficient to prevent recording of identifiable waveforms. During manipulation of the brainstem, damage to the cochlea was indicated by an increase in EOAE latency and its eventual disappearance. A total hearing loss in the operated ear was revealed after surgery. Monitoring cochlear function with EOAEs is probably best considered at present as an adjunct to auditory brainstem response monitoring of the composite cochlea and eighth nerve, thus providing differential information.

Comparison of manual and computer-controlled self-recorded audiometric methods for serial monitoring of hearing.

Manual and self-recorded audiograms obtained from 240 ears on two occasions 2-3 years apart were compared, with the objective of establishing the preferred method for serial monitoring of hearing thresholds. The self-recording method incorporates an objective scoring algorithm which is compared with subjective scoring carried out independently by two experienced audiology staff members. The objective scoring method agreed well with the subjective method but gives substantial advantages in terms of cost and freedom from scorer bias. The variability associated with manual audiometry was somewhat lower than that associated with self-recording audiometry when used for serial monitoring.

CT abnormalities in schizophrenia. A preliminary study of their correlations with P300/P200 electrophysiological features and positive/negative symptoms.

Computed tomographic scans were scored blindly for the size of cerebrospinal fluid spaces in a group of nine medicated schizophrenics and a group of nine age-matched normal volunteers without psychiatric or medical problems. Overall, ten of the 18 computed tomography (CT) features measured were significantly enlarged in the schizophrenic group. These abnormal CT features were then correlated with electrophysiological and clinical measurements performed on the schizophrenic patients. Left sylvian fissure enlargement, thought to reflect temporal lobe tissue loss, was highly correlated with a left temporal scalp region feature of the auditory P300 measure (T3 electrode) that differentiated schizophrenics and normals, and both the left sylvian fissure enlargement and the P300 measure were highly correlated with positive symptoms (total score on the Scale for the Assessment of Positive Symptoms). Frontal superficial (cortical) sulcal enlargement was prominent in the schizophrenic group and was highly correlated with another electrophysiological measure, auditory P200, at left central scalp locations. There was no significant correlation between left sylvian fissure and frontal sulcal enlargement within the schizophrenic group, and intercorrelations between CT variables in the schizophrenic group were, in general, less significant than in the control group. Although we should be cautious about generalizability because of the small number of patients, these data are compatible with the hypothesis that different subgroups of schizophrenic pathological features are characterized by different CT, electrophysiological, and clinical presentations.

Relative benefits of stepped and constant bore earmoulds: a crossover trial.

Twenty-one first-time hearing aid candidates took part in a crossover trial which compared a stepped earmould of the 8CR design with a standard constant-bore earmould, each fitted to a low-powered National Health Service behind-the-ear hearing aid. Before fitting the aid, and also after 2-week trials with each earmould, aided speech-in-noise discrimination scores were obtained, along with subjective ratings according to a series of descriptive scales, and overall preference for one or other of the aids. Aided speech-in-noise scores were, on average, 2.4% higher for the stepped earmould. Two-thirds of the subjects preferred the stepped earmould and it was also rated as more clear on a clear-hazy descriptive scale. After the 4 week trial period, there was a tendency for the stepped earmould to be preferred by subjects with more sensitive hearing thresholds at 2 kHz and higher aided speech-in-noise scores with either earmould, although this was not true at the initial fitting.

Two syndromes of schizophrenic psychopathology associated with left vs. right temporal deficits in P300 amplitude. Four case reports.

In four schizophrenic patients, we examined the relationship between clinical course, including neuroleptic response, and the following biological and psychological measures: topography of the auditory P300 event-related potential, computerized tomography (CT), Andreasen's positive and negative symptom scales, the Thought Disorder Index, and a neuropsychological test battery. Two previous studies in our laboratory had shown that schizophrenic patients were differentiated from a matched normal control group by a left temporal scalp region deficit in P300 topography. This present report compares two schizophrenic patients with the typical left temporal P300 topography deficit with two schizophrenic patients with a right temporal P300 topography deficit. The two right temporal deficit patients had more positive symptoms, more thought disorder, more severely impaired functioning, earlier age of onset, poorer response to neuroleptic medications, more diffuse cognitive deficits on a neuropsychological testing battery, and poorer premorbid history than the two left temporal deficit patients. There was some evidence for the presence of more CT abnormalities suggestive of frontal lobe pathology in the right temporal deficit patients.

On the prediction of the el nino of 1986-1987.

Three different classes of numerical models successfully predicted the occurrence of the El Niño of 1986-87 at lead times of 3 to 9 months. Although the magnitude and timing of predicted ocean surface temperatures were not perfect, these results suggest that routine prediction of moderate to lare El Niño events is feasible. The key to the success of the models lies in recognizing or simulating the low-frequency, large-scale changes in the tropical ocean-atmosphere system that give rise to El Niño events.

An examination of the borderline diagnosis in children.

A retrospective study of 86 children aged 6-12 years who had been hospitalized for psychiatric reasons revealed that adult criteria for borderline personality disorder could identify a group of children with many of the features attributed in the literature to the borderline child. The relative paucity of significant differences between the children identified as borderline and those identified as nonborderline raises questions about the validity and utility of the term. Further work is necessary to clarify the meaning of a vulnerability to psychotic regression in the disturbed child and the relation of such a vulnerability to the adult borderline personality disorder.

A theory for el nino and the southern oscillation.

A coupled atmosphere-ocean model is presented for El Niño and the Southern Oscillation that reproduces its major features, including its recurrence at irregular intervals. The interannual El Niño-Southern Oscillation cycle is maintained by deterministic interactions in the tropical Pacific region. Ocean dynamics alter sea-surface temperature, changing the atmospheric heating; the resulting changes in surface wind alter the ocean dynamics. Annually varying mean conditions largely determine the spatial pattern and temporal evolution of El Niño events.

Oceanographic events during el nino.

El Niño events, the most spectacular instances of interannual variability in the ocean, have profound consequences for climate and the ocean ecosystem. The 1982-1983 El Niño is perhaps the strongest in this century. El Niño events usually have followed a predictable pattern, but the recent event differs markedly. The physical oceanography of this El Niño is described and compared with that of earlier events.