Background A 52-year-old woman whose last known pregnancy was 12 years before presentation was diagnosed with mixed trophoblastic tumor that included placental-site trophoblastic tumor, epithelioid trophoblastic tumor, and focal choriocarcinoma. There was no clear evidence of metastatic disease on initial evaluation. Investigations Histopathology, laboratory tests, immunohistochemistry, chest X-ray, CT scan of the chest, abdomen, and pelvis, fine-needle aspiration biopsy, PET-CT scan.Diagnosis Metastatic chemoresistant placental-site trophoblastic tumor positive for EGFR, VEGF receptor, and platelet-derived growth factor receptor. Management Abdominal hysterectomy, bilateral salpingo-oophorectomy, pelvic radiation, etoposide, methotrexate, actinomycin D/cyclophosphamide and vincristine chemotherapy, left thoracotomy with wedge resection, taxol, etoposide, cisplatin therapy, right thoracotomy with wedge resection.

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Channel estimation problem is addressed for freespace optical communications impaired by optical turbulence. Estimators which are motivated by the minimum mean square error (MMSE) estimation criterion are proposed for the estimation of optical signal intensity in p-i-n and APD-based freespace optical (FSO) communication systems. A shot noise limited condition is assumed. The received signal intensity is modelled using a log-normal (LN) probability density function (pdf) for low (< 0.75) scintillation indices and a negative exponential pdf for scintillation indices in the vicinity of 1. When considering APDbased receivers, only the low scintillation scenario is considered. With the aid of simulation, it is shown that the proposed estimators outperform maximum likelihood (ML) estimators for small scintillation indices.

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Receiver architectures are suggested for the detection of optical field using avalanche photodiode ͑APD͒ arrays. It is assumed that optical field is modulated using either binary pulse-position modulated ͑BPPM͒ or on-off keying ͑OOK͒, and that direct-detection is used to recover the optical signal. It is further assumed that the optical field is exposed to weak atmospheric turbulence. Receivers motivated by the maximum a posteriori ͑MAP͒ rule for OOK and BPPM communications are suggested. Due to the complexity of the suggested receivers, suboptimum combining schemes are presented. In one scheme, a simple summation of the output of APDs is utilized to render a decision. In alternate schemes, for BPPM and OOK scenarios, weighting mechanisms that combine the output of detectors in an optimum manner are suggested. For binary PPM signaling, the proposed weighting mechanism maximizes the signal-to-noise ratio ͑SNR͒. For OOK signaling, the weighting mechanism is an improvised optimization of the linear summation of the outputs of the APDs. Simulation results are presented to underscore the superiority of the weighted combining methods as compared to the simple summation algorithm.

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