Analysis of long transients and detection of early warning signals of extinction in a class of predator-prey models exhibiting bistable behavior.

In this paper, we develop a method of analyzing long transient dynamics in a class of predator-prey models with two species of predators competing explicitly for their common prey, where the prey evolves on a faster timescale than the predators. In a parameter regime near a singular zero-Hopf bifurcation of the coexistence equilibrium state, we assume that the system under study exhibits bistability between a periodic attractor that bifurcates from the singular Hopf point and another attractor, which could be a periodic attractor or a point attractor, such that the invariant manifolds of the coexistence equilibrium point play central roles in organizing the dynamics. To find whether a solution that starts in a vicinity of the coexistence equilibrium approaches the periodic attractor or the other attractor, we reduce the equations to a suitable normal form, and examine the basin boundary near the singular Hopf point. A key component of our study includes an analysis of the long transient dynamics, characterized by their rapid oscillations with a slow variation in amplitude, by applying a moving average technique. We obtain a set of necessary and sufficient conditions on the initial values of a solution near the coexistence equilibrium to determine whether it lies in the basin of attraction of the periodic attractor. As a result of our analysis, we devise a method of identifying early warning signals, significantly in advance, of a future crisis that could lead to extinction of one of the predators. The analysis is applied to the predator-prey model considered in Sadhu (Discrete Contin Dyn Syst B 26:5251-5279, 2021) and we find that our theory is in good agreement with the numerical simulations carried out for this model.

Learning chronobiology by improving Wikipedia.

Although chronobiology is of growing interest to scientists, physicians, and the general public, access to recent discoveries and historical perspectives is limited. Wikipedia is an online, user-written encyclopedia that could enhance public access to current understanding in chronobiology. However, Wikipedia is lacking important information and is not universally trusted. Here, 46 students in a university course edited Wikipedia to enhance public access to important discoveries in chronobiology. Students worked for an average of 9 h each to evaluate the primary literature and available Wikipedia information, nominated sites for editing, and, after voting, edited the 15 Wikipedia pages they determined to be highest priorities. This assignment (http://www.nslc.wustl.edu/courses/Bio4030/wikipedia_project.html) was easy to implement, required relatively short time commitments from the professor and students, and had measurable impacts on Wikipedia and the students. Students created 3 new Wikipedia sites, edited 12 additional sites, and cited 347 peer-reviewed articles. The targeted sites all became top hits in online search engines. Because their writing was and will be read by a worldwide audience, students found the experience rewarding. Students reported significantly increased comfort with reading, critiquing, and summarizing primary literature and benefited from seeing their work edited by other scientists and editors of Wikipedia. We conclude that, in a short project, students can assist in making chronobiology widely accessible and learn from the editorial process.

Haemosuccus pancreaticus due to true splenic artery aneurysm: a rare cause of massive upper gastrointestinal bleeding.

"Haemosuccus pancreaticus" is an unusual cause of severe upper gastrointestinal bleeding and results from rupture of splenic artery aneurysm into the pancreatic duct. More commonly, it is a pseudoaneurysm of the splenic artery which develops as sequelae of pancreatitis. However, true aneurysm of the splenic artery without pancreatitis has rarely been incriminated as the etiologic factor of this condition. Owing to the paucity of cases and limited knowledge about the disease, diagnosis as well as treatment become challenging. Here we describe a 60-year-old male presenting with severe recurrent upper gastrointestinal bleeding and abdominal pain, which, after considerable delay, was diagnosed to be due to splenic artery aneurysm. Following an unsuccessful endovascular embolisation, the patient was cured by distal pancreatectomy and ligation of aneurysm.

Laparoscopic common bile duct exploration using a rigid nephroscope.

BACKGROUND: Patients with cholelithiasis and choledocholithiasis are increasingly managed with laparoscopic bile duct exploration and cholecystectomy. Large impacted bile duct stones continue to defy laparoscopic extraction. This study explored the feasibility of laparoscopic bile duct clearance using a rigid nephroscope, which is suited to extracting large stones. METHOD: This prospective study recruited patients with large bile duct stones and a bile duct wider than 8 mm on ultrasonography. In addition to standard ports for laparoscopic cholecystectomy, a custom-made 9-mm port was introduced in the epigastrium for the rigid nephroscope, which was negotiated into the bile duct through a choledochotomy. Rigid graspers and lithotripters were introduced through the nephroscope to fragment and remove the calculi. RESULTS: Between December 2005 and September 2008, 18 patients had nephroscope-guided bile duct exploration (mean(s.d.) age 49(13.9) years, bile duct diameter 11.3(2.3) mm). Three patients had solitary stones and 15 had multiple calculi. Most of the stones were removed with graspers, but the lithotripter was required in five patients. The mean(s.d.) hospital stay was 6(2.3) days. Two patients required postoperative endoscopic retrograde cholangiopancreaticography for residual stones. CONCLUSION: The rigid nephroscope was useful for laparoscopic bile duct exploration, particularly for large impacted stones.

True knot in Ryles tube: a case report.

Insertion of Ryles tube is a simple routine procedure. During its insertion, minor complications like trauma to nose, nasopharynx and oral cavity do happen from time to time. But as the Ryles tube is usually inserted blindly, potentially life threatening complications like inadvertent entry into trachea, cranial cavity and intravascular penetration have been reported. Folds and kinks may occur, but true knot of the Ryles tube, which we now report, is very rare.

Preliminary antinociceptive, antioxidant and cytotoxic activities of Leucas aspera root.

The ethanolic extract of Leucas aspera root was subjected to acetic acid induced writhing inhibition, 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging assay and brine shrimp lethality bioassay for screening of antinociceptive, antioxidant and cytotoxic activity, respectively. The extract produced significant writhing inhibition in acetic acid induced writhing in mice at the doses of 250 and 500 mg/kg. The extract showed a significant free radical scavenging activity with an IC(50) of 8 microg/ml. The extract showed significant lethality to brine shrimp with an LC(50) value.

Antinociceptive activity of Derris uliginosa.

The ethanol extract of leaves of Derris uliginosa given by oral route at dose of 250 and 500 mg/kg produced a significant inhibition on acetic acid-induced writhing in mice.

Assessment of noise level in Burdwan town, West Bengal.

Cities and towns of the world are now facing enormous rise of noise pollution problem due to very high population rise, transport congestion and associated commercial and industrial activities. Burdwan, a district headquarter (100 km away from Kolkata) is one such town where noise pollution is very frequent. In order to assess noise level, noise data were collected from various places of the town by sound level meter with a duration of 30 minutes/location during specified time like 6.00 am, 10.00 am, 1.00 pm, 4.00 pm and 6.00 pm. Most of the monitoring places either belongs to silence category or commercial category areas. From the tabulated data, it was found that sound level lies within the range of 64-85 dB or above in different time at different places. The locations that belong to the silence zone have the noise level up to 90 dB. Statistically noise level in all these zones differ significantly at their peak hours. Noise pollution adversely affects our environment as well as human beings. Sound causes both pathological and psychological disorders in human beings. Implementation of rules and regulations under section 20, 21J, 41, 68(I), 70, 90, 111A of Environment Protection Act, 1986 and of course various technological methods and public awareness are very essential to check noise pollution in Burdwan town.

Analgesic, diuretic, and anti-inflammatory principle from Scoparia dulcis.

Scoparinol, a diterpene, isolated from Scoparia dulcis showed significant analgesic (p < 0.001) and anti-inflammatory activity (p < 0.01) in animals. A sedative action of scoparinol was demonstrated by a marked potentiation of pentobarbital-induced sedation with a significant effect on both onset and duration of sleep (p < 0.05). Measurement of urine volume after administration of scoparinol indicated its significant diuretic action.

Preliminary studies on the antiinflammatory, analgesic and diuretic activity of stagninol, a sesquiterpene isolated from Persicaria stagnina.

Stagninol, a sesquiterpene, isolated from Persicaria stagnina Linn showed significant antiinflammatory and analgesic activity (P < 0.001) in animals. A sedative action of stagninol was revealed by a marked potentiation of pentobarbital induced sedation with significant effect on both onset (P < 0.001) and duration (P < 0.01) of sleep. Measurement of urine volume after administration of stagninol indicated its significant diuretic action. Biochemical investigations revealed that both crude extract and stagninol showed dose dependent reduction of blood uric acid and blood urea nitrogen (BUN). There was an increase in serum glutamic pyruvic transaminase (SGPT) and serum alkaline phosphatase (SAP) level with the crude extract but stagninol showed no significant changes of serum glutamic oxaloacetic transaminase (SGOT), SGPT and SAP level.

Subpolar tuberculoid leprosy.

Existence of subpolar tuberculoid leprosy was postulated by a few leprologists to explain clinical variations near the tuberculoid pole but failed to precisely identify the same. An attempt has been made to describe the clinical and histological features of subpolar tuberculoid leprosy. 76 cases of the TT-BT range according to Ridley-Jopling classification were examined by detailed clinical, histological and immunological methods. Definite clinical and histological discrepancies from either BT or TTp were seen in 30 (39.4%) cases, confirming the existence of subpolar tuberculoid leprosy (TTs) and thus clarifying the immunological spectrum of leprosy.