Listening for rain: Principal component analysis and linear discriminant analysis for broadband acoustic rainfall detection.

Rain falling on the ocean creates acoustic signals. Ma and Nystuen [(2005). J. Atmos. Oceanic Technol. 22, 1225-1248] described an algorithm that compares three narrowband "discriminant" frequencies to detect rain. In 2022, Trucco, Bozzano, Fava, Pensieri, Verri, and Barla [(2022). IEEE J. Oceanic Eng. 47(1), 213-225] investigated rain detection algorithms that use broadband spectral data averaged over 1 h. This paper implements a rainfall detector that uses broadband acoustic data at 3-min time resolution. Principal Component Analysis (PCA) reduces the dimensionality of the broadband data. Rainfall is then detected via a Linear Discriminant Analysis (LDA) on the data's principal component projections. This PCA/LDA algorithm was trained and tested on 5 months of data recorded by hydrophones in a shallow noisy cove, where it was not feasible to average spectral data over 1 h. The PCA/LDA algorithm successfully detected 78 ± 5% of all rain events over 1 mm/h, and 73 ± 5% of all rain events over 0.1 mm/h, for a false alarm rate of ≈ 1% in both cases. By contrast, the Ma and Nystuen algorithm detected 32 ± 5% of the rain events over 1.0 mm/h when run on the same data, for a comparable false alarm rate.

Experimental realization of a one-atom laser in the regime of strong coupling.

Conventional lasers (from table-top systems to microscopic devices) typically operate in the so-called weak-coupling regime, involving large numbers of atoms and photons; individual quanta have a negligible impact on the system dynamics. However, this is no longer the case when the system approaches the regime of strong coupling for which the number of atoms and photons can become quite small. Indeed, the lasing properties of a single atom in a resonant cavity have been extensively investigated theoretically. Here we report the experimental realization of a one-atom laser operated in the regime of strong coupling. We exploit recent advances in cavity quantum electrodynamics that allow one atom to be isolated in an optical cavity in a regime for which one photon is sufficient to saturate the atomic transition. The observed characteristics of the atom-cavity system are qualitatively different from those of the familiar many-atom case. Specifically, our measurements of the intracavity photon number versus pump intensity indicate that there is no threshold for lasing, and we infer that the output flux from the cavity mode exceeds that from atomic fluorescence by more than tenfold. Observations of the second-order intensity correlation function demonstrate that our one-atom laser generates manifestly quantum (nonclassical) light, typified by photon anti-bunching and sub-poissonian photon statistics.

A therapeutic trial of amniotic epithelial cell implantation in patients with lysosomal storage diseases.

To determine whether allografts of normal amniotic epithelium might provide a nonimmunogenic cellular source of exogenous lysosomal enzymes, subcutaneous implants of amniotic epithelium were performed in six children with clinically advanced storage diseases. The clinical and the biochemical status of each patient was observed for several weeks after amniotic epithelial cell implantation (AECI). Serial studies of blood samples from each patient in the post-AECI period did not demonstrate any increase in levels of deficient lysosomal hydrolase. In two patients, quantitative urinary excretion of substrate was also studied and did not show consistent alterations after AECI. No patient had objective improvement in clinical or neurodevelopmental status following AECI. Two patients died with progressive disease at 2 1/2 and 3 1/2 mo after AECI; no residual amniotic epithelium was found at postmortem examination. Four patients are alive with progressive disease at 6-14 mo after AECI. We conclude that allografts of normal human amnion do not provide sufficient replacement hydrolases for clinical or biochemical improvement in lysosomal storage diseases.

Relationship of diaphragmatic contractility to diaphragmatic blood flow in newborn lambs.

We determined the relationship of diaphragmatic contraction rate to diaphragmatic blood flow (Qdi), metabolism, and contractility in nine open-chested mechanically ventilated newborn lambs. The diaphragm was paced for 15 min at slow (20/min) and fast (100/min) contraction rates each followed by a 30-min rest period. There was a mild reduction in transdiaphragmatic pressure (Pdi) during the slow contraction period accompanied by a shift to the right of the curve relating stimulation frequency (10-100 Hz) to Pdi. Pdi returned to control at the start of the fast contraction period, but then fell by 30% within 2 min with continued fast contraction rates. The frequency-Pdi curve was significantly shifted to the right. Qdi, O2 transport, and O2 consumption increased during slow contraction and to an even greater extent during fast contraction. Fractional O2 extraction reached an apparent maximum during slow contraction. Lactate efflux from the right phrenic vein during slow contraction remained unchanged from control. During fast contraction lactate efflux rose proportionately more than did O2 consumption. We conclude that the energy demands at fast rates of diaphragmatic contraction in newborn lambs cannot be met by aerobic metabolism alone despite increasing O2 transport to the diaphragm.

Cost evaluation of alternative pharmaceutical tableting processes by simulation.

A simulation model and a subsequent computer program were developed as experimentation methods for evaluating tableting processes with respect to cost. These methods also allow estimation of the various times involved in a tableting operation (e.g., the processing time). The model was programmed in FORTRAN using the GASP IV simulation language. After verification of the program, experiments were run that involved comparing different levels of specific input variables to determine which variable had an effect on the cost-time relationships of a particular processing method. Among the possible input variables chosen for evaluation were the drying method, the type of tableting machine, the batch size, the labor rate, and the operation of the equipment in the process. An analysis of variance was made, and three separate regression equations were developed that described the relationship between the input variables and the dependent variables of processing cost and time. Graphs were developed from the regression equations by manipulating them through series of different independent variables. These graphs then were used in determining minimum costs and times, breakeven points, and rates of change, as well as in simple evaluation of processes through graphic representation. By using the simulation program to run experiments and then by analyzing them, results can be obtained to help in making intelligent decisions about the cost-time relationships of a particular tableting procedure before it is implemented.

Multipurpose central venous access in the immunocompromised pediatric patient.

During a 21-month period, 50 consecutive pediatric oncology patients undergoing bone marrow transplantation and/or cytoreductive chemotherapy had 61 silastic central venous catheters placed to facilitate their therapy. All catheters were used for medications, routine blood sampling, and transfusions, with 45% also used for hyperalimentation and 57% used for bone marrow transplantation. Catheters were utilized during both inpatient and outpatient therapy periods. Total catheter days numbered 8455, an average of 139 days per catheter. Forty-seven catheters (77%) were removed electively or were in place at time of patient death. Seven were removed for mechanical complications (1/1409 catheter days). Four additional episodes of presumed catheter sepsis were managed with antibiotics and did not require catheter removal (40% of septic episodes). One catheter is still in place after 585 days. Complication rates were not influenced by this multiple use protocol. With standardized catheter care and surveillance, multipurpose, long-term central venous access can be safely utilized in the immunosuppressed pediatric patient.

Severe pancreatico-duodenal injuries: the effectiveness of pyloric exclusion with vagotomy.

The operative management and clinical course of 17 patients treated for severe pancreatico-duodenal injuries from 1983 to 1990 was reviewed. The etiology of these injuries was gunshot wound in 15 patients; stab wound in 1 patient; and a motor vehicle accident in 1 patient. Seven patients presented in shock with a systolic blood pressure of less than 80. At exploration, 57 associated injuries were found in the 17 patients including 16 major vascular injuries. All patients were treated with pyloric exclusion and drainage. Vagotomy was performed in eight patients. None of these 17 patients were felt to have extensive enough damage to require pancreatico-duodenectomy. Two patients died in the immediate postoperative period of severe coagulopathy and two patients died of sepsis. Seven patients had complications related to the pancreatico-duodenal injury. All seven developed pancreatic fistulas; three also had pancreatitis and two developed multiple enterocutaneous fistulas. Systemic complications included pulmonary complications in eight patients and sepsis in five patients, including two patients with abdominal abscesses. Six patients bled in the immediate postoperative period secondary to coagulopathy. Three patients had complications related to pyloric exclusion. One developed afferent loop syndrome necessitating reoperation. The other two had marginal ulcers, which either perforated or bled and required reoperation. Of interest, neither of these two patients had vagotomy initially. The results of this series confirm the effectiveness of pyloric exclusion with vagotomy for severe pancreatico-duodenal injury.

Primary common bile duct closure following exploration: an effective alternative to routine biliary drainage.

Primary closure of the common bile duct following exploration has been safely and effectively performed, as advocated by Halsted, provided no evidence of pancreatitis, cholangitis, or ampullary obstruction exists. Using this precedent, the operative management and clinical course of 29 patients undergoing common bile duct exploration (CBDE) for choledocholithiasis from 1986 to 1992 were reviewed. Ten patients had primary closure of the common bile duct (CBD) following choledochotomy and exploration, and 17 patients had t-tube placement. Two patients had CBDE through an enlarged cystic duct that was then ligated. Patients were selected for t-tube placement if they had pancreatitis, ascending cholangitis, evidence of retained stones, or ampullary obstruction. Two patients in this series died. No patient with primary closure of the CBD suffered a biliary complication including retained stones, biliary fistula, pancreatitis, or bile peritonitis. Serious systemic complications were comparable in both groups. The results of this series support the safety of primary common bile duct closure in selected cases.

Use of absorbable mesh as an aid in abdominal wall closure in the emergent setting.

A surgeon has many options available to aid in the closure of abdominal wall defects in the elective setting. In the emergent setting, active infection or contamination increases the likelihood of infection of permanent prosthetic material and limits the surgical options. In such settings, we have used absorbable mesh (Dexon) as an adjunct to fascial closure until the acute complications resolve. To evaluate the effectiveness of this technique, we reviewed the outcome of such closures in 26 critically ill patients. Between July 1987 and June 1993, 26 patients were identified who had placement of absorbable mesh as part of an emergent laparotomy at a major urban trauma center. Through a retrospective chart review, the incidence of complications and outcome of the closure were tabulated. Seven patients were initially operated on for trauma. Two of the patients had mesh placement at their initial procedure secondary to fascial loss from trauma. The remainder of the patients hd mesh placement during a subsequent laparotomy for complications related to their initial procedure. Indications for these laparotomies included combinations of wound dehiscence, intra-abdominal abscess, anastomotic disruption, and perforation. Mesh placement in patients with intra-abdominal infection created effectively open abdominal wounds that allowed continued abdominal drainage, but required extensive wound care. Despite the absorbable nature of the mesh and often prolonged hospital stay in these ill patients, none of them required reoperation for dehiscence, recurrence of intra-abdominal abscess, or infection of the mesh.(ABSTRACT TRUNCATED AT 250 WORDS)

Rational use of antibiotics for perforated appendicitis in childhood.

Gangrenous and perforated appendicitis was reviewed in 300 pediatric patients. Those with only gangrene generally had a benign course regardless of whether antibiotic therapy was used. However, patients with local perforation or generalized peritonitis had a high incidence of infective complications if they were not treated with antibiotics. Children treated with ampicillin, gentamicin, and clindamycin had markedly fewer wound infections and abscesses and were able to tolerate a diet and go home sooner than those receiving ampicillin and/or gentamicin.

Treatment of segmental tracheomalacia and bronchomalacia by implantation of an airway splint.

A silastic reinforced marlex mesh splint was inserted surgically to support a collapsing airway in 3 children with tracheomalacia and 1 with bronchomalacia. The operation was well tolerated and no complications occurred. The splint successfully eliminated symptoms of airway collapse in all children. Its effect on airway growth is not yet certain. This method is applicable to patients with tracheomalacia in whom vascular suspension does not eliminate collapse and for those with bronchomalacia in whom pulmonary resection might otherwise be necessary.

THe significance of fever following operations in children.

To determine the incidence and clinical significance of early postoperative fever, all children (n = 256) undergoing surgery in the main operating theatres during a 4 wk period were studied. Admission and operating room data were reviewed and the clinical record was monitored at 12 hourly intervals for the first 3 postoperative days. The patients were followed for 1 mo for the development of recognizable complications. Seventy-three children (28.5%) developed fever greater than 38 degrees C but in only four (1.6%) did this represent a septic process. Physical examination led to the proper diagnosis in all. Risk factors that correlated statistically with postoperative fever were operation of greater than 2 hr (p less than .001), intraoperative transfusion (p less than .001), preexisting infection (p less than .01) and the use of preoperative antibiotics (p less than .001). Anatomic site of operation, age and sex were not significant factors. We conclude that many factors other than infection are responsible for post-operative fever. Further, only a very small proportion of children with early postoperative fever develop significant septic complications. In the assessment of postoperative fever a protocol which indiscriminately includes lab investigations and X-rays is costly and usually not diagnostic. Laboratory tests are indicated mainly to confirm diagnoses suspected by clinical evaluation.

One-year experience in a regional pediatric trauma center.

During 1982, 267 children with life-threatening injuries were admitted to the Maryland Regional Pediatric Trauma Center at the Johns Hopkins Hospital. Seventy-three percent of patients arrived directly from the injury scene by helicopter (46%), ambulance (50%), or other (4%). Mechanisms of injury included motor vehicle accidents (MVA; 55%), falls (27%), assaults (8%), and sports and other injuries (10%). In 75% of MVA the child was a pedestrian. Fifty-one percent of injuries were single organ system, 29% involved two systems, and 20% involved three or more systems. Remarkably, the mortality of 6.7% was not affected by the number of organ systems involved, but was directly related to the presence or absence of head injury. Fourteen of seventeen deaths resulted from head injury. Eighty percent of documented liver and spleen injuries were managed nonoperatively. This nonoperative plan of management simplified the optimal treatment of head injury. The high frequency of head injury has mandated a more aggressive approach to the management of brain trauma including intracranial monitoring to facilitate control of cerebral edema. Our data demonstrate that an excellent quality of life may be anticipated even in children with severe head injury.

Fiberoptic transillumination: a new tool for the pediatric surgeon.

Transillumination (TI) is a safe and reliable technique for evaluating masses or the presence of free air in the thorax or abdomen. TI can also be of help in the accurate placement of catheters or needles in the chest, abdomen, bladder, or vessels. Its use in several hundred cases has been documented by this report.

Open lung biopsy in the immunocompromised pediatric patient.

Rapidly progressive pulmonary distress occurs as a secondary complication in immunocompromised pediatric patients. These patients usually develop a pattern of diffuse alveolar and/or interstitial infiltrates on chest x-ray and pursue a rapidly downhill course despite intensive respiratory support with the use of multiple and varied antimicrobial regimens. These patients are subjected to diagnostic open lung biopsies to establish a diagnosis. The diagnostic value of open lung biopsy and its current impact on therapy is not clearly established. This retrospective study attempts to determine the impact of open lung biopsy on diagnosis and therapeutic outcome. Between November, 1974, and October, 1982, 40 diagnostic open lung biopsies were performed on immunocompromised patients with clinically progressive respiratory disease. Adequate follow-up for complete evaluation was possible in 34 of these patients. Most of these patients had hematologic malignancies and all were on chemotherapeutic drugs at time of open lung biopsy. Open lung biopsy was considered helpful, ie, resulted in a change in antimicrobial therapy or substantiated preoperative therapy, in 17 of our 34 patients (50%). A "treatable" condition, amenable to antimicrobial therapy, was diagnosed in 16 of our patients (47%). Pneumocystis carinii pneumonitis (PCP) was the most common diagnosis in 11 (69%) of our "treatable" patients. The remaining five "treatable" patients had sarcoidosis (1), histiocytosis X (1), bacterial pneumonitis (1) and fungal pneumonitis (2). No diagnosis was achieved by open lung biopsy in ten (30%) of our patients. There were two complications attributable to open lung biopsy (6%), including one death. All PCP patients treated with trimethoprim sulfamethoxazole (T/S) survived.(ABSTRACT TRUNCATED AT 250 WORDS)

New techniques in the diagnosis and operative management of Siamese twins.

New techniques of 2-D sonography and radionucleotide Disofenin scanning allowed noninvasive evaluation of thoracoomphalopagus Siamese twins and successful separation at four days of age. Twin girls joined at the lower sternum and upper abdomen and weighing 15 lbs, were transferred at five hours of age after caesarian-section delivery. Scout films revealed high intestinal obstruction in twin A. 2-D sonography showed separate and normal hearts with different rates and attached pericardial sacs. Labeled Disofenin given intravenously to twin A was excreted exclusively in her gallbladder and bile ducts; vice versa for twin B. Because operation was necessary to correct jejunal atresia in twin A, further growth and development was not an option and the parents agreed to total correction. Sternal and pericardial separation and division of common midline-liver was followed by primary diaphragmatic defect repair and Dacron-cloth fascial reconstruction to upper abdominal wall and complete soft-tissue and skin closure in a ten-hour operation. Segmental jejunal resection and anastomosis with gastrostomy was added in baby A. The new tests greatly simplified definition of the anatomical relationships and implemented rapid correction in these newborn conjoint twins.

Efficacy of emergency room thoracotomy in pediatric trauma.

With improved rapid transportation systems, an increasing number of children may arrive at the emergency room (ER) without detectable vital signs and may undergo vigorous resuscitation, including emergency room thoracotomy, aortic cross clamping, and open cardiac massage. Of 1,287 pediatric trauma admissions between 1980 and 1985, 101 deaths were recorded. Fifty (50%) of the deaths occurred in the ER. Thirty-three of the patients were pronounced dead with obvious irreversible injuries, while 17 (34%) with suspected thoracoabdominal injuries underwent ER thoracotomy during resuscitation. None of the 17 patients had detectable vital signs upon arrival to the ER. Fifteen patients had multisystem injuries associated with blunt trauma and two with isolated penetrating injuries. Despite maximal conventional resuscitation and ER thoracotomy, none of the 17 patients survived. In this group of pediatric blunt trauma victims who appear initially salvageable, and present in the ER with no detectable vital signs, ER resuscitative thoracotomy did not influence survival. ER thoracotomy in children, therefore, should be reserved for patients presenting with penetrating thoracic injuries or blunt injuries associated with detectable vital signs and deterioration despite maximal conventional therapy.

Life-threatening airway obstruction as a complication to the management of mediastinal masses in children.

Life-threatening airway obstruction from large mediastinal masses in children poses a difficult diagnostic and therapeutic dilemma, requiring the close coordination of a pediatric surgeon, anesthesiologist, radiologist, and oncologist. To focus on this problem, the anesthetic and surgical management of 50 consecutive children with mediastinal masses treated between 1978 and 1984 were reviewed. Thirty children presented with respiratory symptoms; nine had life-threatening respiratory compromise with dyspnea, orthopnea, and stridor. Thirteen of these symptomatic children had marked compression of the trachea and/or mainstem bronchi on radiographic studies. The tracheal cross-sectional area which was measured by computed tomography was decreased by 35% to 93% of the normal tracheal dimensions in these children. Nonresectable malignant neoplasms including lymphoma, Hodgkin's disease, rhabdomyosarcoma, and neuroblastoma were the eventual diagnoses in 10 of these patients. The other 3 patients were less than 4 years old and had benign lesions. General anesthesia was judged to be prohibitively risky in 5 of 13 patients. The diagnosis was established by node or needle biopsy under local anesthesia, and general anesthesia was deferred until the compromised airway was alleviated by radiation and chemotherapy. General anesthesia with endotracheal intubation was administered to 8 patients, 5 of whom developed total airway obstruction. Using a variety of maneuvers, ventilation was reestablished in all 5 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The efficacy of computed tomography in evaluating abdominal injuries in children with major head trauma.

Physical examination may be unreliable in the evaluation of children with blunt abdominal trauma particularly in those with associated major head injuries. In the absence of obvious clinical signs or physical findings of intraabdominal injury, the usefulness of abdominal computed tomography in children is controversial. To test the efficacy of CT scans, a 12-month prospective study of computed tomography for the initial assessment of children with blunt abdominal trauma and major head injuries was carried out. Of 320 pediatric trauma admissions to our regional trauma center, 65 consecutive patients with Glasgow Coma Scores less than ten were managed with sequential head and abdominal computed tomography in the emergency room for (1) closed head injury and (2) suspected abdominal trauma. Fifteen patients (23%) were found to have significant intraabdominal injury. Only two required operative intervention. No patients died as a result of the abdominal injuries. In children with significant head trauma and suspected abdominal trauma, combined head and abdominal CT proved to be reliable.

Prediction of successful primary closure of congenital abdominal wall defects using intraoperative measurements.

To determine whether intragastric pressure (IGP) and central venous pressure (CVP) would reliably predict successful primary closure of congenital abdominal wall defects (omphalocele/gastroschisis) in newborn infants, we developed the following prospective intraoperative management protocol. Following a temporary trial of fascial closure, infants who had an IGP less than 20 mm Hg or an increase in CVP of less than 4 mm Hg were primarily closed. If IGP was greater than 20 mm Hg or if CVP increased by more than 4 mm Hg, the temporary closure of the abdomen was reopened and a prosthetic silo was placed. Ten infants who were less than 24 hours old and averaged 2.7 kg (range, 1.4 to 4.2 kg) and 37-weeks gestation (range, 32 to 41 weeks) were studied. Eight infants met criteria for primary closure. Their IGP averaged 14 +/- 4 mm Hg (+/- SD) (range, 8 to 19 mm Hg), and their increase in CVP averaged 1 +/- 2 mm Hg (range, -2 to 3 mm Hg). In the two infants who required staged repair, IGP averaged 25 +/- 1 mm Hg (+/- SD) (range, 24 to 25 mm Hg), and the increase in CVP averaged 7 +/- 1 mm Hg (range, 6 to 8 mm Hg). All patients were anesthetized with fentanyl (12.5 micrograms/kg) and paralyzed with metocurine (0.3 mg/kg) intraoperatively. There were no postoperative complications in either group of patients related to increased intraabdominal pressure, and all patients were extubated within 48 hours of the initial surgery. We conclude that the intraoperative measurement of changes in IGP and CVP can serve as a guide to the operative management of congenital abdominal wall defects and can reliably predict successful outcome following repair.