A controlled birth and death process model of optimal product pricing under stochastically changing demand

We consider the problem of product pricing when the firm's market share is changing stochastically according to a birth and death process. The current market share together with the price prevailing determine the current rate of profit made as well as the birth and death rates. The optimal pricing policy must balance the immediate advantage of setting a high price in terms of increased current profit against the disadvantage in terms of a possible erosion of the future market share. We formulate a continuous-time Markov decision model and analyse it using a recent technique developed by Lippman [6] for optimization of exponential queueing systems. The optimal pricing policy is characterized as having a sort of monotonicity property. We also analyse the dependence of the optimal policy on the problem parameters and indicate further extensions of the model.

Dynamic investment strategies for a risky R and D project

During the course of an R and D project, it is often meaningful and possible to evaluate its status, so that this information may be used for making better financing decisions over time. The project status changes stochastically due to the internal (technological) and the external (market) uncertainties, the former being partially controlled by expenditure of resources. In addition to the resource expenditure strategy, the manager must also decide when to terminate the project. Once the project is terminated, a terminal return is collected, whose value depends on the final project status. It is shown that the project should be terminated if the current status is either too low or too high to make further expenditure worthwhile. Otherwise, for an intermediate (promising) status of the project, an aggressive investment strategy is shown to be optimal. Thus, the model unifies the problems of optimally undertaking, financing and terminating an R and D project in face of various uncertainties.

Non psammomatous melanocytic schwannoma presenting as a subcutaneous nodule: A rare presentation of a rare lesion

Melanocytic schwannoma (MS) is an extremely rare soft tissue tumor accounting for less than 1% of all primitive nerve sheath tumors, with a predilection for spinal nerve involvement. To date, only 20 cases of cutaneous/subcutaneous MS have been described in literature. Here, we describe a case of MS presenting as a subcutaneous nodule in a 22-year-old male in right thigh. On examination, the nodule measured 2.5 × 2.0 × 1.5 cm with overlying skin showing a bluish hue and an ulcer. With a preoperative diagnosis of hemangioma, the patient was taken up for wide local excision and was diagnosed as a case of non psammomatous melanocytic schwannoma based on clinical, histological, and immunohistochemical studies. Immunohistochemistry revealed positivity with S-100, HMB-45, and Melan A with pericellular Laminin positivity. Carney's syndrome was ruled out. MS needs to be differentiated from other pigmented lesions like pigmented neurofibroma, Bednar tumor, cellular blue neavus, and especially malignant melanoma, which has an obvious ominous prognosis. Since MS can show unpredictable behavior especially in absence of overt malignant features, a long term follow up with or without radiotherapy is recommended.

Primary mantle cell lymphoma of appendix

We present a case of immunohistochemically proven primary mantle cell lymphoma of appendix that presented as a mass in right iliac fossa. The usual presentation of gastrointestinal mantle cell lymphoma is in the form of multiple lymphomatous polyposis. Mantle cell lymphoma has a unique immunohistochemistry and genetic abnormality.

Carcinosarcoma of renal pelvis with immunohistochemical correlation

Carcinosarcoma, a malignant tumor with biphasic morphology is uncommon in the renal pelvis. Immunohistochemistry (IHC) plays an important role in establishing the diagnosis and differentiating it from other biphasic malignant tumors. We present a rare case of immunohistologically confirmed carcinosarcoma of renal pelvis in a 42-year old female, which possibly developed on a background of multicentric squamous cell carcinoma arising as a consequence of chronic irritation caused by calculi.

Stability of a charged drop near a conductor wall

The effect of conductor boundaries on the deformation and stability of a charged drop is presented. The motivation for such a study is the occurrence of a charged conductor drop near a conductor wall in experiments (Millikan-like set-up in studies on Rayleigh break-up) and applications (such as electrospraying, ink-jet printing and ion mass spectroscopy). In the present work, analytical (linear stability analysis (LSA)) and numerical methods (boundary element method (BEM)) are used to understand the instability. Two kinds of boundaries are studied: a spherical, conducting, grounded enclosure (similar to a spherical capacitor) and a planar conducting wall. The LSA of a charged drop placed at the center of a spherical cavity shows that the Rayleigh critical charge (corresponding to the most unstable l = 2 Legendre mode) is reduced as the non-dimensional distance ̂d = (b - a)/a decreases, where a and b are the radii of the drop and spherical cavity, respectively. The critical charge is independent of the assumptions of constant charge or constant potential conditions. The trans-critical bifurcation diagram, constructed using BEM, shows that the prolate shapes are subcritically unstable over a much wider range of charge as [Formula: see text] decreases. The study is then extended to the stability of a charged conductor drop near a flat conductor wall. Analytical theory for this case is difficult and the stability as well as the bifurcation diagram are constructed using BEM. Moreover, the induced charges in the conductor wall lead to attraction of the drop to the wall, thereby making it difficult to conduct a systematic analysis. The drop is therefore assumed to be held at its position by an external force such as the electric field. The case when the applied field is much smaller than the field due to inherent charge on the drop ((a(3)ρg)/(3ε(0)Ψ(2)) ≪ 1 is considered. The wall breaks the fore-aft symmetry in the problem, and equilibrium, predominantly prolate shapes corresponding to the legendre mode, l = 2 , are observed. The deformation increases with increasing charge on the drop. The breakup of the prolate equilibrium shapes is independent of the legendre modes of the initial perturbations. The prolate perturbations are subcritically unstable. Since the equilibrium prolate shapes cannot continuously exchange instability with equilibrium oblate shapes, an imperfect transcritical bifurcation is observed. A variety of highly deformed equilibrium oblate shapes are predicted by the BEM calculations.

Low-grade malignant proliferating pilar tumor simulating a squamous-cell carcinoma in an elderly female: a case report and immunohistochemical study

A 65-year-old lady presented with an ulcerated lesion over the occipital region of nine-year duration, an incisional biopsy of which was reported as squamous-cell carcinoma. A wide local excision was performed and the tissue was sent for histopathological examination which revealed a low-grade malignant pilar tumor. Focal invasion and atypia were noted. Immunohistochemical (IHC) analysis revealed positivity for CD34 and calretinin immunomarkers favoring outer root sheath origin. Ki67 immunostains revealed a relatively low immunoreactivity indicating the low-grade nature of the tumor; however, p53 immunostain showed strong diffuse nuclear staining confirming the malignant nature of the tumor. Proliferating pilartumors (PPT) are rare tumors and less than 100 well-documented cases of malignant PPT have been reported so far in the literature. These tumors have been recently classified into benign, low- and high-grade malignant tumors and statistically significant difference was found in their biological behavior. However, we propose that IHC can be of immense value in assisting the subtyping of the tumor, so that the behavior and role of adjuvant therapy can be validated in future studies.

Congenital cystic adenomatoid malformation in an adolescent: an unusual presentation with pleural effusion and pneumatocele

Congenital cystic adenomatoid malformation (CCAM) encompasses a continuum of hamartomatous cystic lung lesions characterised by the presence of abnormal bronchiolar structures of varying sizes or distribution. The CCAM is a disorder of infancy with majority of the cases being diagnosed within the first two years of life. We describe CCAM in a 13-year-old girl complaining of recurrent lower respiratory tract infections since infancy who presented with post-infectious pneumatocele with loculated pleural effusion, and suspected abscess formation and had undergone resection.

Mal connects TLR2 to PI3Kinase activation and phagocyte polarization

The recognition of bacterial lipoproteins by toll-like receptor (TLR) 2 is pivotal for inflammation initiation and control in many bacterial infections. TLR2-dependent signalling is currently believed to essentially require both adaptor proteins MyD88 (myeloid differentiation primary response gene 88) and Mal/TIRAP (MyD88-adapter-like/TIR-domain-containing adaptor protein). TLR2-dependent, but MyD88-independent responses have not been described yet. We report here on a novel-signalling pathway downstream of TLR2, which does not adhere to the established model. On stimulation of the TLR2/6 heterodimer with diacylated bacterial lipoproteins, Mal directly interacts with the regulatory subunit of phosphoinositide 3-kinase (PI3K), p85alpha, in an inducible fashion. The Mal-p85alpha interaction drives PI3K-dependent phosphorylation of Akt, phosphatidylinositol(3,4,5)P3 (PIP(3)) generation and macrophage polarization. MyD88 is not essential for PI3K activation and Akt phosphorylation; however, cooperates with Mal for PIP(3) formation and accumulation at the leading edge. In contrast to TLR2/6, TLR2/1 does not require Mal or MyD88 for Akt phosphorylation. Hence, Mal specifically connects TLR2/6 to PI3K activation, PIP(3) generation and macrophage polarization.

Temperature-dependent variation in toxicity of insecticides against Earias vitella (Lepidoptera: Noctuidae)

The toxicity of synthetic pyrethroids was found to be negatively correlated with temperature, whereas contrasting correlation was observed with the toxicity of organophosphorous compounds chlorpyriphos and quinalphos, which was most toxic at higher temperature. A similar phenomenon was observed in endosulfan at higher temperature and humidity combination. The insecticide molecules indoxacarb and spinosad were effective among the insecticides tested. Indoxacarb was effective at lower temperature, and spinosad was effective at all the temperature and relative humidity combinations with minor difference in LD50 values. During both the years, however, the levels of resistance were higher in second year compared with previous year.

FNAC of salivary gland lesions with histopathological correlation

HYPOTHESIS

Analysis of salivary gland lesions by FNAC and correlation with histopathology. To evaluate utility of FNAC in salivary gland lesions.Back ground: Salivary gland lesions form about 2-6.5% of all head and neck neoplasms in adults. They are easily accessible for FNAC (Fine Needle Aspiration Cytology) and risks of fistula formation or tumour implantation are low compared surgical biopsy. Also, cytology can provide a distinction between asalivary and non salivary lesion, benign and malignant lesions so also specific and non specific inflammation.

METHODS

Seventy patients were studied prospectively over two years. FNAC was done using 10 cc syringes and 20-22 no. needle. Histomorphology was assessed on routine H & E (haemotxylin and eosin) stained paraffin sections. SPAS (periodic acid Schiff) and mucicarmine satins were also done.

RESULTS

80% of the lesions were neoplastic (61% benign, 31% malignant) and 20% were neoplastic. Pleomorphic adenoma was the most frequent benign neoplasm while mucoepidermoid carcinoma was the most frequent malignant lesion. Among the non neoplastic lesions, the maximum number of cases were of chronic sialadentis. In the present study, FNAC has a sensitivity of 94.54% and specificity of 80.95% for neoplastic lesions.

CONCLUSIONS

FNAC was found to be a useful diagnostic tool in the evaluation of salivary gland lesions because of its simplicity, excellent patient compliance and rapid diagnosis. This cost effective tool is invaluable in planning the surgical management of the patient.

Targeting dsRNA-specific single-chain Fv antibody fragments to different cellular locations in Nicotiana tabacum L

Expression of antibodies or antibody fragments in plants is a useful tool for producing active antibody derivatives for diagnostic or pharmaceutical purposes as well as for immunomodulation. We investigated the effect of cellular expression site on the stability and yield of double-stranded RNA (dsRNA)-specific single-chain Fv-fragments (scFv) in transgenic tobacco. Two antibodies (J2 and P6) belonging to the V23(J558) heavy chain variable gene family but differing in the light chain variable domain were used. scFvs were targeted to the cytoplasm - with or without anchoring them in the plasma membrane -, into the endoplasmic reticulum (ER) and to the apoplast. Although high mRNA concentrations were detected in all cases, scFv proteins accumulated only when scFvs were made ER-resident by appropriate signal sequences. When the ER retention signal was removed to allow scFv-secretion to the apoplast, no scFv-proteins were detected. Despite the strong homology of the VH-sequences of J2 and P6 antibodies, only P6 provided a stable scFv scaffold for intracytoplasmic expression. J2-scFv could not be stabilised either by adding a C-terminal stabilisation signal or by anchoring the protein on the cytoplasmic side of the plasma membrane (PM). It was found that dsRNA-specific J2-scFvs are active in vivo and enhance Potato Virus Y induced symptoms in infected tobacco. This is the first report describing the expression and biological effect of RNA-specific antibodies in plants.

Platelet volume indices in patients with coronary artery disease and acute myocardial infarction: an Indian scenario

AIMS

To study platelet volume indices (PVI) in the spectrum of ischaemic heart diseases.

METHODS

A total of 210 cases were studied; 94 patients had unstable angina (UA) or acute myocardial infarction (AMI) diagnosed on the basis of history, characteristic electrocardiographic changes, and increased cardiac enzyme activities. Seventy patients had stable coronary artery disease (stable CAD) or were admitted for a coronary angiography or coronary artery bypass graft procedure. The third group comprised 30 age and sex matched healthy controls with no history of heart disease and a normal electrocardiogram.

RESULTS

All PVI-mean platelet volume (MPV), platelet distribution width (PDW), and platelet large cell ratio (P-LCR)-were significantly raised in patients with AMI and UA (mean MPV, 10.43 (SD, 1.03) fL; mean PDW, 13.19 (SD, 2.34) fL; mean P-LCR, 29.4% (SD, 7.38%)) compared with those with stable CAD (mean MPV, 9.37 (SD, 0.99) fL; mean PDW, 11.35 (SD, 1.95) fL; mean P-LCR, 22.55% (SD, 6.65%)) and the control group (mean MPV, 9.2 (SD, 0.91) fL; mean PDW, 10.75 (SD, l.42) fL; mean P-LCR, 20.65% (SD, 6.14%)).

CONCLUSIONS

Larger platelets are haemostatically more active and are a risk factor for developing coronary thrombosis, leading to myocardial infarction. Patients with larger platelets can easily be identified during routine haematological analysis and could possibly benefit from preventive treatment. Thus, PVI are an important, simple, effortless, and cost effective tool that should be used and explored extensively, especially in countries such as India, for predicting the possibility of impending acute events.

Profile of bone marrow examination in HIV/AIDS patients to detect opportunistic infections, especially tuberculosis

Morphological evaluation of 140 bone marrow aspirations received in haematopathology laboratory with serologically established HIV infection, along with other relevant special haematological tests, was done during 1st Jan 1999 - 31st Dec 2002 at state government run tertiary care General Hospital in Maharashtra state, India. Out of 140 cases: 118 (84.28%) patients had anaemia, 25 (17.86%) had leukopenia, while 13 (9.28%) were thrombocytopenic. Dyserythropoiesis was present in 18 (12.86%) cases, dysmyelopoiesis 37 (26.43%) and micromegakaryocytes were noted in 44 (31.43%) cases. Haemophagocytosis was evident in 8 (5.71%) cases. Plasmacytosis encountered in 120 (85.71%) cases was a common feature. Based on clinical profile and results of other investigations 56 (40%) patients were clinically diagnosed to be of Mycobacterium tuberculosis (TB). Of these, 18 (12.86%) bone marrow aspirates were positive for AFB, Mycobacterium tuberculosis. In 4 cases cryptococci were demonstrated (Mucicarmine stain). There was one case each of Histoplasma capsulatum and leishmaniasis. One patient showed dense parasitemia with Plasmodium falciparum. One patient had immunoblastic lymphoma and showed bone marrow infiltration. Findings in this study strongly indicate that in HIV/AIDS, AFB stain should be done on each marrow aspirate to rule out tuberculosis in countries like India; where TB and AIDS are marching together.

A study of mast cells in granulomatous lesions of skin, with special emphasis on leprosy

76 skin biopsies that included material from 7 controls, 65 granulomatous skin lesions and 2 each of granulation tissue and chronic non-specific inflammation, were subjected to histopathological evaluation on haematoxylin and eosin and pertinent special stains. Mast cell study was done on slides stained by toluidine blue method, with special reference to their location, and morphology and cell count were done with the help of occculomicrometre. In normal skin, mast cell density was 11.43/mm2 with a range of 6-22/mm2 and an S.D. of 5.94. Highest value in the whole series was seen in TVC (66/mm2), followed by lupus vulgaris (50/mm2). Mast cell counts were normal in indeterminate and TT leprosy and showed a rise over the immunological spectrum BT to LL, with values in LL being 32.86/mm2 (28-40/mm2).

Pathology of Toxoplasma myocarditis in acquired immunodeficiency syndrome

Involvement of the myocardium by Toxoplasma gondii is seen in patients of acquired immunodeficiency syndrome (AIDS), mostly in association with toxoplasma encephalitis. Only few patients die as a direct result of cardiac dysfunction. Clinico-pathological findings of three cases of toxoplasma myocarditis are reported, one of which presented and died due to massive pericardial effusion. All cases showed diffuse myocarditis with parasites on histopathological examination. Incidence of toxoplasma myocarditis in patients dying with AIDS was 8.3% (3 out of 36 cases).

Autopsy study of maternal deaths

OBJECTIVES

To obtain an insight into the underlying disorder or pathologies in different organs or systems, and to attempt clinicopathologic correlation in maternal deaths.

METHODS

This is a retrospective study of 95 maternal autopsies done from 1993 to 2000 in Sassoon General Hospital, Pune, India. External examination, in situ examination, gross and microscopic examination was done in each case. The cause of death was arrived at after reviewing clinical details, available investigations, morphological findings, and clinicopathologic correlation.

RESULTS

Ninety-five (45.02%) out of 211 maternal deaths were autopsied. Out of 95, there were 47 (49.5%) direct obstetric deaths, and 33 (34.7%) indirect obstetric deaths. Fifteen (15.8%) deaths were unrelated to pregnancy, 14 of which were due to infections.

CONCLUSIONS

Hypertensive disorders associated with pregnancy (24.2%) and anemia (14.7%) were most common. In the hypertensive group, important findings were disseminated intravascular coagulation, hemorrhages in different organs and thromboemboli. Two cases were HIV seropositive. The autopsy helped to elucidate factors contributing to death and pathology in different organ systems.

Entomopthoromycosis--report of four cases

Entomopthoromycosis is a rare subcutaneous infection and manifests in two clinically distinct forms. Subcutaneous zygomycosis which manifests as a painless nodule on the trunk or the extremities and rhinofacial zygomycosis which is a locally progressive infection of the nasal cavity, paranasal sinuses and soft tissues of the face. Neither of these two forms occur in patients with underlying disease or defective immunity. Here we report four cases of entomopthoromycosis.

Autopsy study of pediatric deaths

OBJECTIVE

Childhood autopsies occurring during January 1997 to December 1999 were reviewed.

METHOD

Of the total 1,445 deaths autopsied, 441 (30.5%) were of pediatric patients.

RESULT

Of these deaths, 70.3% occurred during neonatal period, 8.6% in infancy, and 21.1% in childhood. Birth asphyxia (57.7%) was the most frequent mode of death in the neonatal period. Infections (67.2%) predominantly accounted for infant and childhood mortality, those of respiratory tract (46.1%) being most frequent in infancy, early and mid childhood, and enteric fever in late childhood (33.3%). Discrepancy between ante-mortem and post-mortem diagnosis occurred in 29 cases (6.6%).

CONCLUSION

Autopsy is an important clinical tool providing useful information to the physician. Few published reports are available on pediatric autopsies. This study aims to help in a better understanding of causes of deaths in neonates, infants and children.

Amyloid (spheroid) deposits in pituitary adenoma presenting as Cushing disease--a case report

A rare case of pituitary adenoma with spheroid amyloid deposits encountered in a 40 year old male is presented.

Niemann Pick disease--a case report

Niemann Pick disease is a rare disorder occuring in paediatric age group. The clinical features, hematological characteristics and autopsy findings in an one year old male diagnosed to have Niemann Pick disease are presented.

Fluorescence in pigmented basal cell carcinoma caused by formaldehyde

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