Ultratunable Quantum Frequency Conversion in Photonic Crystal Fiber.

Quantum frequency conversion of single photons between wavelength bands is a key enabler to realizing widespread quantum networks. We demonstrate the quantum frequency conversion of a heralded 1551 nm photon to any wavelength within an ultrabroad (1226-1408 nm) range in a group-velocity-symmetric photonic crystal fiber, covering over 150 independent frequency bins. The target wavelength is controlled by tuning only a single pump laser wavelength. We find internal, and total, conversion efficiencies of 12(1)% and 1.4(2)%, respectively. For the case of converting 1551 to 1300 nm we measure a heralded g^{(2)}(0)=0.25(6) for converted light from an input with g^{(2)}(0)=0.034(8). We expect that this photonic crystal fiber can be used for myriad quantum networking tasks.

From photons to phonons and back: a THz optical memory in diamond.

Optical quantum memories are vital for the scalability of future quantum technologies, enabling long-distance secure communication and local synchronization of quantum components. We demonstrate a THz-bandwidth memory for light using the optical phonon modes of a room temperature diamond. This large bandwidth makes the memory compatible with down-conversion-type photon sources. We demonstrate that four-wave mixing noise in this system is suppressed by material dispersion. The resulting noise floor is just 7×10(-3) photons per pulse, which establishes that the memory is capable of storing single quanta. We investigate the principle sources of noise in this system and demonstrate that high material dispersion can be used to suppress four-wave mixing noise in Λ-type systems.

Influence of failed vascular bypass procedures on conversion of below-knee to above-knee amputation levels.

From 1975 to 1980, 79 major limb amputations were performed from a group of 552 lower extremity vascular reconstructions with glutaraldehyde-stabilized umbilical vein grafts. All amputations were performed in instances in which limb salvage had been the indication for the attempted bypass (n = 520)--an incidence of 15.2%. Twelve of 51 below-knee (BK) amputations were converted to above-knee (AK) levels (crude failure rate, 23.5%). The highest crude failure rate occurred after failed bypass to the popliteal artery (33.3%); the lowest occurred after failed tibial bypass (16.7%), and the peroneal arteries were intermediate (22.2%). In addition to these 12, 28 primary AK amputations were performed. Excluding nine cases judged to require AK amputations before the attempted vascular reconstruction, success/failure rates for the entire series and each of the reconstruction types were calculated. Success, defined as a healed BK stump, occurred least after failed popliteal bypass, 44.5%, compared to 71.4% and 53.8% for the tibial and peroneal groups, respectively. Thus, failure of a popliteal bypass was more apt to lead to an AK amputation (56.5%) than failure of a distal bypass. In fact, tibial bypass failure leading to an AK stump occurred at a frequency (28.6%) almost similar to that obtained by other investigators when no previous bypass had been performed. Comparative cumulative graft patency and limb salvage rate data confirm the value of reconstructive vascular surgery, particularly in the peroneal group where negativism with regard to its clinical usefulness persists. With improved case selectivity and surgical expertise, increasing limb salvage rates can be secured while minimizing the definite morbidity of conversion of BK to AK amputation with failed vascular bypass.

Distal arteriovenous fistula as an adjunct to maintaining arterial and graft patency for limb salvage.

Sixty-one distal arteriovenous fistulas (dAVFs) were constructed as adjuncts to tibial and peroneal vascular reconstructive procedures in 58 patients threatened with imminent limb loss. Specific indications for dAVF construction were absent or deficient pedal arches, usually associated with small, calcareous crural vessels. Conventional bypasses had been previously performed in 35 patients. Cumulative graft patency rates were 56%, 39%, and 18% at 6, 12, and 24 months, respectively. For the same intervals, the figures were 56%, 52%, and 52% (P less than 0.001 at 24 months) for nonAVF reconstructions (n = 49). The corresponding cumulative limb salvage rates were 62%, 52%, and 40% for the dAVF group and 78%, 72%, and 72% for the nonAVF group (P less than 0.05 at 24 months). The perioperative mortality rate was 7% (four of 61). Twenty-four amputations were required, of which 16 were below the knee and six despite patent grafts. There was no significant morbidity attributable directly to the dAVF. Cardiac output showed no deviations from normal values. Primary causes of early failure were infection (n = 4), absence of satisfactory veins (n = 6), and inappropriate case selection (n = 7). Intimal hyperplasia led to dAVF closure and graft failure in 13 patients. This study shows that dAVFs can maintain graft patency by diversion of the overload on a high-resistance vascular bed and, secondarily, by augmentation of inflow. Immediate survival of the limb still depends on the arterial runoff, as retrograde venous flow caused by venous valvular incompetence is a delayed development. Adjunctive dAVF is justified in selected cases where conventional bypass failure has occurred or is predictable by increased pedal vascular resistance.

Remote hydraulic syringe actuator: its use to avoid radiation exposure during intraoperative arteriography.

A simple, inexpensive device consisting of a double hydraulic syringe system and a holding fixture was devised for intraoperative arteriography to avoid exposure of personnel to radiation. The procedure of intraoperative angiography has thus become safer, less time consuming, and more reliable in obtaining high-quality angiographic studies.

Prostate-specific antigen-producing cells in the bone marrow of a patient with early-stage prostate cancer.

This report describes a clinical case that supports the hypothesis that occult bone marrow disease may exist even in early-stage and low prostate-specific antigen (less than 10 ng/mL) prostate cancer. The concept of adding androgen suppression to definitive local therapy in these patients is discussed.

Inadequacies and hazards of chymopapain injections as treatment for intervertebral disc disease.

Chymopapain chemonucleolysis was performed on 100 patients with primary lumbar intervertebral disc disease. The results were compared with those of 174 patients who underwent laminotomy, foraminotomy, and discectomy. Primary lumbar intervertebral disc disease was arbitrarily divided into degenerative, complex, previous surgical, and simple disc syndromes. No difference was seen between chemonucleolysis and surgery in the first three divisions; between 55 percent and 60 per cent of patients responded successfully to treatment. In the simple disc division 89 per cent of the surgical and 60 per cent of the chemonucleolysis patients had successful results.

Adjunctive arteriovenous fistula with tibial and peroneal reconstruction for limb salvage.

Arteriovenous fistulas were constructed as an adjunct to femoral peroneal and tibial bypasses in 13 patients threatened by imminent limb amputation. Previous attempts at conventional vascular reconstructive procedures had failed in nine patients. Deficient or absent pedal arches were noted in all patients, as were poor quality or small crural arteries. Graft patency was achieved in 11 cases and limb salvage in 10. There was no mortality. A steal phenomenon occurred in one patient and was successfully treated by secondary popliteal vein ligation. These preliminary results clearly indicate that an adjunctive arteriovenous fistula can maintain patency in a femoral tibial or peroneal bypass graft while preserving flow into the markedly diseased distal circulation.

Improved patient selection for enzymatic lysis of peripheral arterial and graft occlusions.

Intraarterial thrombolysis by remote intravenous or direct intraarterial infusion of streptokinase is possible. The latter may be more effective with a lesser potential for systemic hemorrhagic complications because of the smaller dose administered directly in the area. Fifty patients with prosthetic graft, embolic, and renal artery occlusions were evaluated. Embolic occlusion responded dramatically, particularly since lytic therapy was initiated at an early stage. Patients with severe ischemia or those with simple localized occlusion were best treated by surgical means. Successful thrombolysis was also obtained with renal artery occlusions combined with percutaneous transluminal angioplasty. The management of patients with prosthetic graft occlusion by lytic therapy is complex. Optimal results can be obtained in patients presenting with occluded grafts after the immediate postoperative period and in those in whom previous satisfactory runoff has been demonstrated. Failure of lysis in this group is associated with a high incidence of limb loss due to unreconstructable obliterative disease. Successful lysis of occluded prosthetic grafts will often require corrective angioplasty or surgical revision.

Epidural anesthesia as an adjunct to retroperitoneal aortic surgery.

Recent developments in vascular surgery suggest that the retroperitoneal approach to the aorta and the use of epidural anesthesia for lower limb revascularization are associated with decreased morbidity and shorter hospital stays. By combining these principles, we sought to determine if retroperitoneal aortic surgery could be performed under epidural anesthesia and if this might be advantageous. Over a 16-month period, 57 patients underwent aortic surgery via the retroperitoneal (n = 33) or transperitoneal (n = 24) approach. In the former, epidural anesthesia was employed in 10 patients, general anesthesia in 3, and combined epidural anesthesia and general anesthesia in the remaining 20. In the transperitoneal group, general anesthesia was employed in 21 patients and combined epidural anesthesia and general anesthesia in 3. Both groups were similar in age and gender, but risk factors were predominant in the retroperitoneal group. With the exception of one death due to aspiration, there were no significant differences between the transperitoneal and retroperitoneal groups with respect to overall morbidity, pulmonary complications, and length of stay in the intensive care unit and hospital. Despite these findings, we favor the combination of epidural and general anesthesia for retroperitoneal aortic surgery. Morbidity was significantly decreased (p less than 0.05) in low-risk retroperitoneal patients when combined epidural anesthesia and general anesthesia were employed.

Results of a prospective, randomized trial of surgery versus thrombolysis for occluded lower extremity bypass grafts.

PURPOSE: The purpose of this study was to prospectively evaluate the treatment of patients with occluded lower extremity bypass grafts, comparing surgical revascularization with catheter-directed thrombolysis. MATERIALS AND METHODS: One hundred twenty-four patients (68% male and 32% female) with lower limb bypass graft occlusion (46 autogenous and 78 prosthetic) were prospectively randomized to surgery (n = 46) or intra-arterial catheter-directed thrombolysis (n = 78) with recombinant tissue plasminogen activator (rt-PA) 0.1 mg/kg/h modified to 0.05 mg/kg/h for up to 12 hours, or urokinase (UK) 250,000 U bolus followed by 4,000 U/min for 4 hours, then 2,000 U/min for up to 36 hours. A composite clinical outcome including death, amputation, ongoing/recurrent ischemia, and major morbidity was analyzed on an intent-to-treat basis at 30 days and 1 year. RESULTS: The average duration of graft occlusion was 34.0 days, with 58 (48%) presenting with acute ischemia (0 to 14 days) and 64 (52%) with chronic ischemia (> 14 days). Thirty-nine percent randomized to lysis failed catheter placement and required surgical revascularization. Overall, there was a better composite clinical outcome at 30 days (P = 0.023) and 1 year (P = 0.04) in the surgical group compared with lysis, due predominately to a reduction in ongoing/recurrent ischemia, most notable in autogenous grafts. However, following successful catheter placement, patency was restored by lysis in 84%, and 42% had a major reduction in their planned operation. One-year results of successful lysis compared favorably with the best surgical procedure, which was new graft placement. Acutely ischemic patients (0 to 14 days) randomized to lysis demonstrated a trend toward a lower major amputation rate at 30 days (P = 0.074) and significantly at 1 year (P = 0.026) compared with surgical patients, while those with > 14 days ischemia showed no difference in limb salvage but higher ongoing/recurrent ischemia in lytic patients (P < 0.001). Patients with occluded prosthetic grafts had greater major morbidity than did those with occluded autogenous grafts (P < 0.02). CONCLUSIONS: Proper catheter positioning currently limits the potential of catheter-directed thrombolysis for lower extremity bypass graft occlusion. Patients with graft occlusion > 14 days have a significantly better outcome when treated surgically, with a new bypass being the best surgical option. However, in patients with acute limb ischemia (< 14 days) successful thrombolysis of occluded lower extremity bypass grafts improves limb salvage and reduces the magnitude of the planned surgical procedure. Patients with occluded prosthetic grafts suffer more major morbid events compared with occluded autogenous grafts.

Tibial arteriovenous fistula: successful use for limb salvage.

Embolization of atheromatous material from abdominal aortic aneurysms to the distal arterial circuit is a well-recognized clinical entity causing the "blue toe syndrome." A case is presented in which this phenomenon resulted in obliteration of the pedal arch and thrombosis of the tibial arteries. As a result, forefoot gangrene, severe leg ischemia and anterior and posterior compartment syndromes occurred. Salvage of the extremity required an extraordinary approach with the construction of an arteriovenous fistula between the posterior tibial vessels. The literature on the use of therapeutic and adjunctive arteriovenous fistulas and their physiology is discussed.

Dual function of the distal arteriovenous fistula for maintenance of arterial and venous prosthetic graft patency in the lower extremity.

Venous hypertension, severe swelling, and tissue necrosis occurred in a limb previously subjected to distal arterial bypass plus adjunctive arteriovenous fistula. Occlusion of the popliteal vein had not been recognized during the early treatment period. Subsequent to identification of this mechanism, limb salvage was achieved with an interposition graft of the popliteal vein using externally supported PTFE. The prereconstruction venous pressure gradient of 29 cm H2O was virtually abolished immediately after reestablishing venous outflow. The distal arteriovenous fistula, initially established to maintain prosthetic arterial graft patency, now serves, in this case, a dual function by additionally maintaining prosthetic venous graft patency. An intact deep venous system is critical for achieving successful arterial reconstruction and to avoid the complications associated with an occluded outflow tract in the face of augmented inflow.

Cutaneous malignant melanoma.

From January 1973 to December 1985, 136 patients with primary cutaneous malignant melanoma were treated at Englewood Hospital. Pathologic types, methods of treatment, and results are discussed and a comparison of results is made with other institutions.

Entangling macroscopic diamonds at room temperature.

Quantum entanglement in the motion of macroscopic solid bodies has implications both for quantum technologies and foundational studies of the boundary between the quantum and classical worlds. Entanglement is usually fragile in room-temperature solids, owing to strong interactions both internally and with the noisy environment. We generated motional entanglement between vibrational states of two spatially separated, millimeter-sized diamonds at room temperature. By measuring strong nonclassical correlations between Raman-scattered photons, we showed that the quantum state of the diamonds has positive concurrence with 98% probability. Our results show that entanglement can persist in the classical context of moving macroscopic solids in ambient conditions.