Fetus in fetu in the scrotal sac of newborn

Fetus in fetu (FIF) in the scrotal sac is often overlooked in the differential diagnosis of other scrotal swellings in infants and children. Unlike  teratoma, FIF is a benign disorder. Scrotal FIF is extraordinarily rare and has been reported only twice in the international literature. We describe the case of a 15-day-old neonate who presented with scrotal swelling since birth. Radiography and ultrasound revealed a FIF. On surgical removal and pathological evaluation, the anencephalic fetus had limb buds, male external genitals, and vertebral column, supporting the diagnosis of FIF. FIF in the scrotum is a very rare entity. It should be  differentiated from other scrotal swellings such as teratoma because of the malignant potential of the latter. Preoperative diagnosis is based on radiologic findings. The treatment is complete excision.Keywords: fetus in fetu, pluripotent cells, scrotal swelling, scrotal teratom

Multi-wavelength Selective Crossbar Switch

Switches are used to connect servers together to form a network in datacenters andin telecommunication. This can be done with electronic switches or optical switches.There has been a tremendous effort in the optics community to miniaturize switches withintegrated photonic technology. Many of these switches are single wavelength switches,i.e they connect two ports with a single wavelength channel. These switches under utilizethe channel bandwidth provided by Wavelength Division Multiplexing.In this thesis, I propose a multi-wavelength selective switch that can dynamicallyassign multiple channels for any connection. Such a switch can help scale data centersand drastically reduce cabling complexity. The theory of the switch is developed andmeasurements of the switch fabricated in a Silicon photonics foundry are reported. Anovel on-chip locking mechanism for the switches is also proposed and demonstrated.We measured an average path loss of 10 dB on Gen III 8x4 switch with a standarddeviation of 2 dB. These losses were reduced by a factor of 4 in Gen IV 4x4 switchwith undoped ring resonators to 2.65 dB with a standard deviation of 1.35 dB. Thetuning range of the rings is twice the Gen III 8x4 switch and the Gen IV 4x4 switchis tunable across 4 channels at 400 GHz spacing. We measured a 10 to 90 % largesignal switching time of 15 s. Multiple input Bit Error Rate measurements showednegligible power penalty due to incoherent crosstalk. Ring resonators are also locked totwo channels spaced at 100 and 200 GHz using an on-chip photodetector in an on-chiplocking experiment

Multi-Wavelength Selective Crossbar Switch

Switches are used to connect servers together to form a network in datacenters and in telecommunication. This can be done with electronic switches or optical switches. There has been a tremendous effort in the optics community to miniaturize switches with integrated photonic technology. Many of these switches are single wavelength switches, i.e they connect two ports with a single wavelength channel. These switches under utilize the channel bandwidth provided by Wavelength Division Multiplexing. In this thesis, I propose a multi-wavelength selective switch that can dynamically assign multiple channels for any connection. Such a switch can help scale data centers and drastically reduce cabling complexity. The theory of the switch is developed and measurements of the switch fabricated in a Silicon photonics foundry are reported. A novel on-chip locking mechanism for the switches is also proposed and demonstrated. We measured an average path loss of 10 dB on Gen III 8 × 4 switch with a standard deviation of 2 dB. These losses were reduced by a factor of 4 in Gen IV 4 × 4 switch with undoped ring resonators to 2.65 dB with a standard deviation of 1.35 dB. The tuning range of the rings is twice the Gen III 8 × 4 switch and the Gen IV 4 × 4 switch is tunable across 4 channels at 400 GHz spacing. We measured a 10 to 90 % large signal switching time of 15 s. Multiple input Bit Error Rate measurements showed negligible power penalty due to incoherent crosstalk. Ring resonators are also locked to two channels spaced at 100 and 200 GHz using an on-chip photodetector in an on-chip locking experiment