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At least 19 recordsLinked to original sources
PubMed1987

Internal ventricular defibrillation with sequential pulse countershock in pigs: comparison with single pulses and effects of pulse separation.

We compared single to sequential pulse shocks with different pulse separations on internal cardiac defibrillation by using a catheter and plaque electrodes in open-chest halothane-anesthetized pigs. Ten seconds after fibrillation onset, defibrillation was attempted using trapezoidal pulses of 65% tilt, approximately 5 ms duration and fixed outputs from 1.0 to 50 joules (J). With single pulses, minimum defibrillation energy for the catheter alone was 2.4 +/- 0.3 J/kg (mean +/- standard error) and 2.1 +/- 0.2 J/kg for the catheter tip to plaque configuration. With sequential pulse shocks, the first pulse delivered via the catheter and the second pulse from the catheter tip to the plaque electrode, the energy necessary for defibrillation was dependent on the separation time between the two pulses (2.0 +/- 0.2, 1.5 +/- 0.2, 0.9 +/- 0.1, 1.3 +/- 0.3, 0.6 +/- 0.2, and 1.2 +/- 0.2 J/kg at 100, 10, 1, 0.5, 0.2, and 0.1 ms, respectively). Further, at the 0.2 ms separation, 100% of the animals could be defibrillated with less than 2.0 J/kg (35 J total). We conclude that sequential pulse defibrillation provides a significant improvement over single pulse defibrillation. The optimum separation between the sequential pulses in this study was 0.2 ms.

Animals↗
PubMed1986

Dependence of double-pulse facilitation on amplitude and duration of the depolarization pulses at frog's motor nerve terminals.

Motor nerve terminals of the frog were depolarized by pairs of pulses with 5 to 10 ms interval and the resulting quantal transmitter releases were determined. In 'fixed pulse facilitation', Fc, the second pulse was kept constant, and the effect of a varying pre-pulse was measured, comparing the thus facilitated release after the fixed pulse to control release after the fixed pulse alone. If depolarization in the pre-pulse was increased from threshold to almost saturation level of release, Fc had a maximum, Fc, at about 1/10 the saturation level of release, as reported before. In 'double-pulse facilitation', Fd, two identical pulses were applied, and the facilitated release after the second pulse was compared to control release after the first pulse. On increasing pulse duration from 0.4 to 2.5 ms, at fixed depolarization levels, Fd had a peak at short pulse duration and low release, and declined with increasing pulse duration and release. This dependence is expected if facilitation is caused by 'residual Ca'. Alternatively, if at fixed duration depolarization in the pulses was increased from threshold level, in most preparations Fd rose to a maximum at low depolarization and release, declined to a minimum at the depolarization level of Fc, and rose again for larger depolarizations. In some preparations, and for short pulses, the peak of Fd at low depolarizations was not observed, but always Fd increased with depolarization beyond Fc. The complicated dependence of Fd on depolarization can be explained by the residual Ca theory, if at depolarizations larger than that which produced Fc and the minimum of Fd, Ca-inflow decreases.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Intraoperative comparison of sequential-pulse and single-pulse defibrillation in candidates for automatic implantable defibrillators.

Sixteen survivors of cardiac arrest underwent intraoperative comparison of the effectiveness of sequential-pulse and single-pulse defibrillation. Defibrillation was tested alternately with the single-pulse or sequential-pulse technique 10 seconds into an episode of ventricular fibrillation that was induced with alternating current. The sequential-pulse defibrillation technique using truncated exponential pulses was performed with a right ventricular endocardial catheter and a left ventricular epicardial patch electrode. The first pulse was delivered between the right ventricular apical and the superior vena caval electrode on the right ventricular endocardial catheter. The second pulse was delivered between the right ventricular apical electrode and the left ventricular patch electrode 0.2 ms after termination of the first pulse. Single-pulse defibrillation was performed with a standard intracardiac defibrillation system in which a single truncated exponential pulse was delivered across 2 epicardial patch electrodes positioned over the anterolateral right ventricle and the posterolateral left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and integrated to determine delivered energy. Average defibrillation threshold leading-edge voltage for the sequential pulse technique was 496 +/- 140 V, compared with 365 +/- 157 V for the single-pulse technique (p less than 0.005). Defibrillation threshold leading-edge current for the sequential-pulse technique was 6.0 +/- 2.3 A, compared with 10.6 +/- 5.1 A for the single-pulse method (p less than 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Prospective comparison of sequential pulse and single pulse defibrillation with use of two different clinically available systems.

Sixteen out-of-hospital survivors of ventricular fibrillation underwent a prospective, randomized, intraoperative comparison of sequential pulse and single pulse defibrillation with use of two distinct electrode systems and waveform shapes currently available for clinical use. Defibrillation was tested alternately with either the single pulse or the sequential pulse system 10 s into an episode of ventricular fibrillation. Sequential pulse defibrillation was performed with two 4 ms truncated exponential pulses of constant duration delivered to three equally spaced oval epicardial patch electrodes composed of concentric coils. The posterior left ventricular electrode served as the common cathode. The first anode was over the anterior right ventricle and the second anode was over the anterior left ventricle. Single pulse defibrillation was performed with the standard intracardiac defibrillation system with use of a single truncated exponential pulse with a fixed 65% tilt delivered across two rectangular, wire mesh epicardial patch electrodes positioned over the anterior right ventricle and posterolateral left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and used to determine pulsing resistance and delivered and stored energy. Average defibrillation threshold leading edge voltage for the single pulse technique was 273 +/- 101 V compared with 246 +/- 67 V (11% less) for the sequential pulse technique (p = 0.136). Defibrillation threshold leading edge current for the single pulse technique was 6.7 +/- 2.5 A compared with 5.2 +/- 1.7 A (29% less) for the sequential pulse method (p = 0.005). The defibrillation threshold delivered energy was 5.6 +/- 4.0 J for the single pulse technique and 3.5 +/- 1.8 J (38% less) for the sequential pulse technique (p = 0.021).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The arterial pulse analyzer as a potential replacement for manual pulse palpation in Oriental medicine.

Application of the arterial pulse analyzer now makes it possible to automatically diagnose such geriatric disorders as arteriosclerosis by using simple electrocardiograms and radial, carotid and posterior tibial artery pressure pulse wave charts. If the arterial pulse analyzer is adopted for use in Oriental medical clinics, there will no longer be a need for manual pulse palpation. In brief, applying the arterial pulse analyzer to the 8 key pulses of Oriental medicine yields the following results: 1) 'Slow' or 'rapid' pulses can be defined by the S-S interval (almost identical to the R-R interval of the ECG). 2) 'Slippery' or 'hesitant' pulses can be defined by the S-P time and the Dh/Ch% (P time & Incisura) ratio. 3) 'Floating' or 'submerged' pulses can be defined by the Ph/Ch% (pressure pulse wave to height) ratio. 4) 'Scattered' or 'moderate' pulses can be defined by the S-C- time (E time). Thus, by employing the arterial pulse analyzer, subjectivity problems inherent in the manual pulse palpation used by Oriental medicine for over 1500 years can be analyzed objectively.

Arteriosclerosis↗
PubMed1988

Divergent effects of the antiestrogen tamoxifen and of estrogens on luteinizing hormone (LH) pulse frequency, but not on basal LH levels and LH pulse amplitude in men.

We studied the role of estrogens on LH pulse modulation in men in two ways. Firstly, we compared LH pulse frequency and amplitude in 13 normal men before and after 6 weeks administration of the antiestrogen tamoxifen (10 mg twice daily). Secondly, we compared LH pulse frequency and amplitude between a group of 10 agonadal men not receiving sex steroid treatment and a group of 9 agonadal men (male to female transsexuals) continuously treated with 50 micrograms ethinyl estradiol/day. Tamoxifen administration to normal men resulted in a significant rise in the mean serum LH level from 5.7 +/- 1.3 (+/- SD) to 10.1 +/- 2.4 U/L, which was associated with significant increases in LH pulse frequency (from 4.2 +/- 1.5 to 5.8 +/- 1.7/7 h) and LH pulse amplitude (from 3.8 +/- 0.9 to 4.6 +/- 0.7 U/L). In the group of agonadal men the mean LH pulse frequency was 6.8 +/- 1.5/7 h, while it was 5.9 +/- 1.7/7 h in the estrogen-treated agonadal group (P = NS). The mean serum LH level and LH pulse amplitude were, however, significantly lower in the estrogen-treated agonadal men than in the agonadal men (14.7 +/- 7.0 vs. 34.3 +/- 8.6 and 4.1 +/- 1.8 vs. 7.4 +/- 1.8 U/L, respectively). We conclude that estrogens reduce basal LH levels and LH pulse amplitude. With regard to the modulation of LH pulse frequency our data provide contradictory results. While an antiestrogen increased LH pulse frequency in normal men, estrogen alone produced no change in LH pulse frequency in agonadal men. The study design in the agonadal men ignores the possible interaction of the two major testicular hormones (estradiol and testosterone) on gonadotropin secretion. Therefore, a possible explanation for this discrepancy in the effects of antiestrogen and estrogen could be an interaction between estrogens and androgens on gonadotropin secretion at the level of the LHRH pulse generator.

Adult↗
PubMed1988

Effects of pulse frequency on single-unit baroreceptor activity during sine-wave and natural pulses in dogs.

1. Previous studies using sine-wave pulses have shown that changes in pulse frequency do not alter single-unit activity per unit time. Since baroreceptor activity is phasic with most of the activity occurring in systole, we reasoned that the lack of effect of pulse frequency is due to the associated reciprocal change in duration of systole with sine-wave pulses. Therefore, we tested the hypothesis that change in frequency using natural arterial pulses alters baroreceptor unit activity per unit time. 2. In chloralose-anaesthetized dogs the isolated carotid sinus was connected to an electromagnetic pressure converter driven by a voltage generator that controlled pulse pressure and sine-wave pulse rate. To generate a natural pulse the converter was driven by the output from the pressure channel used to record arterial pressure. Systolic and diastolic pressures were maintained constant by a pressurized air source and an adjustable control on the voltage generator. The rate of natural pulses was decreased by electrical stimulation of the peripheral right vagus nerve which slowed the heart rate of the dog. 3. Decreases in sine-wave rate by approximately 73 pulses/min (from 156 +/- 2 to 83 +/- 1 pulses/min) at a mean pressure of 114 +/- 8 mmHg (n = 13) did not alter activity per unit time (28 +/- 3 vs. 29 +/- 3 spikes/s). 4. In contrast, decreases in natural pulse rate by an average of 78 pulses/min (from 182 +/- 7 to 104 +/- 15 pulses/min) at a comparable mean pressure (104 +/- 7 mmHg) (n = 9) decreased activity per unit time by 28% from 32 +/- 4 to 23 +/- 4 spikes/s (P less than 0.05). Similar findings were observed in five of six single units using an intact (normally perfused) carotid sinus preparation in dogs with heart block and cardiac pacing. 5. The results indicate that a change in natural pulse rate is an important determinant of single-unit baroreceptor activity.

Action Potentials↗
PubMed1992

Controlled trial of pulse methylprednisolone versus two regimens of pulse cyclophosphamide in severe lupus nephritis.

Pulse cyclophosphamide is more effective than prednisone alone in preventing renal failure in lupus nephritis. We undertook a randomised, controlled trial to find out whether pulse methylprednisolone could equal pulse cyclophosphamide in preserving renal function in patients with lupus nephritis, and whether there was a difference between long and short courses of pulse cyclophosphamide in preventing exacerbations. 65 patients (60 female, 5 male; median [range] age 29 [10-48] years) with severe lupus nephritis were assigned randomly to monthly pulse methylprednisolone for 6 months (25 patients), monthly pulse cyclophosphamide for 6 months (20), or monthly cyclophosphamide for 6 months followed by quarterly pulse cyclophosphamide for 2 additional years (20). Patients treated with pulse methylprednisolone had a higher probability of doubling serum creatinine than those treated with long-course cyclophosphamide (p less than 0.04). Risk of doubling creatinine was not significantly different between short and long course cyclophosphamide. However, patients treated with short-course cyclophosphamide had a higher probability of exacerbations than those treated with long-course cyclophosphamide (p less than 0.01). An extended course of pulse cyclophosphamide is more effective than 6 months of pulse methylprednisolone in preserving renal function in patients with severe lupus nephritis. Addition of a quarterly maintenance regimen to monthly pulse cyclophosphamide reduces the rate of exacerbations.

Adolescent↗
PubMed1989

Photoendocrine transduction in cultured chick pineal cells. III. Ouabain (or dark) pulses can block, overcome, or alter the phase response of the melatonin rhythm to light pulses.

A photoentrainment pathway, circadian pacemakers, and the apparatus for regulated melatonin production all reside within chick pineal cells. Pulses of white light (L), or darkness (D), or ouabain (Ob), in otherwise constant red light, induce phase-dependent phase shifts in the rhythm of melatonin output displayed by these cells in static culture. The phase response curves (PRCs) (which describe the relationship between the phase at which a pulse is given and the resulting phase shift) for Ob and for D are quite similar, and differ from the PRC for L pulses. Here, we describe the effects of pulses of Ob, L, and D, in combination, on subsequent phase of the melatonin rhythm. Ob pulses can block, overcome, or alter the phase response to light pulses, depending on the phases and concentrations used. Under appropriate conditions, D pulses can, like Ob, convert the phase response to a light pulse from phase delays to phase advances. Such alterations in the response to a second pulse (L) caused by a first pulse (Ob or D) implies a rapid resetting of the phase of the underlying pacemaker. The interactions of Ob, L, and D are consistent with, but do not require, the convergence of their entrainment pathways on the same oscillating component of the pacemaker.

Animals↗
PubMed1989

Twin pulse facilitation in dependence on pulse duration and calcium concentration at motor nerve terminals of crayfish and frogs.

Phasic release from motor-nerve terminals of crayfish and frogs was elicited and recorded by means of a macro-patch-clamp electrode through which the terminal was depolarized in graded pulses. The tip of the electrode was perfused and the Ca concentration around the terminal, Cae, was controlled independent from that in the superfusion of the muscle, Cab. Release increased with pulse duration with a double-logarithmic slope of 5 to 9 in crayfish and frogs, which represents a form of "early facilitation" (Katz and Miledi 1968). In crayfish, this relation was shifted to longer pulse durations on lowering Cae, while in frogs, in addition, the saturation level of release was suppressed at low Cae. Responses to twin pulses with intervals of 7-10 ms showed facilitation, Fd. When pulse duration of the twin pulses was increased, starting from about 0.5 ms, Fd increased to a maximum, but declined for longer pulses which elicited release approaching the saturation range. On lowering Cae, the maximum of Fd, Fd, increased in amplitude and was shifted to larger pulse durations. Also reduction of Cab increased Fd. The effects of pulse duration and of Cae and Cab on Fd are predicted by the residual Ca theory of facilitation, if it is assumed that changes of Cae produce corresponding changes in Ca inflow during depolarization, and if the resting intracellular Ca concentration is influenced by the extracellular Ca concentration. The large values of early facilitation can not be explained by the residual Ca theory of facilitation and may indicate the action of another depolarization dependent factor which joins in the control of release.

Animals↗
PubMed1985

GnRH pulse frequency determines LH pulse amplitude by altering the amount of releasable LH in the pituitary glands of ewes.

We have measured the size of the releasable pools of LH and FSH in the pituitary glands of ovariectomized ewes in which the pituitary was isolated surgically from the hypothalamus. The ewes were given GnRH pulses (250 ng) every hour (N = 3) or every 2 h (N = 3) for 1 week and then given a high dose GnRH infusion (0.5 micrograms/min) for 4 h. Blood samples were collected to characterize the LH and FSH responses to the GnRH pulses and infusion. The LH, but not FSH, responses to the individual GnRH pulses were pulsatile and the amplitudes of the LH pulses were greater in the sheep receiving pulses every 2 h. The sheep receiving hourly pulses showed lower LH responses to the high-dose infusions than did the sheep receiving pulses every 2 h. These data indicate a relationship between the amplitude of LH pulses and the size of the releasable pool of LH in the pituitary gland. As the frequency of GnRH pulses is decreased the amplitude of the LH responses is increased in direct proportion to the size of the releasable LH pool.

Animals↗
PubMed1986

Pulse oximetry and circulatory kinetics associated with pulse volume amplitude measured by photoelectric plethysmography.

Through a catheter placed in a superficial vein on the finger, we observed a pulsatile venous pressure. To delineate the relationship between the pulsatile venous pressure and the pulse volume amplitude (PVA) recorded by photoelectric plethysmography (PEPG), both tracings were simultaneously recorded. When the PVA changed acutely or gradually, the venous pulse pressure and mean venous pressure simultaneously followed the same trend. We also found that mean PVO2 (135 mm Hg) was greater when the PVA and venous pulse pressure increased above the level (50 mm Hg) observed when they decreased. These findings suggested that the finger pulse detected by PEPG, as well as by pulse oximetry, is caused by pulsations in veins rather than by pulsations in arterial beds. In experiments to evaluate the validity of this hypothesis, we found that the average value of hemoglobin saturation (%SaO2) measured by the pulse oximeter of the dependent fingertip and finger base when dependent was 1.5% and 7.8% lower than when the fingertip and finger base were elevated. Also, the PVA detected by the pulse oximeter followed the same trend as %SaO2. This finding was explained by venous congestion in the dependent finger. On the basis of the high venous pressure, the behavioral trends between the PVA and venous pressure, the high PVO2, and the low %SaO2 and PVA in the dependent finger, we conclude that the PVA of the PEPG is determined mainly by venous pulse volume generated by shunting of arterial pulse via open arteriovenous (AV) anastomoses in the cutaneous circulation.

Adult↗
PubMed1991

The consistency of pulse frequencies and pulse patterns of transcutaneous electrical nerve stimulation (TENS) used by chronic pain patients.

This study records the consistency of transcutaneous electrical nerve stimulation (TENS) pulse frequency and pulse pattern used by 13 chronic patients over a 1 year period. The results show that patients prefer specific pulse frequencies and pulse patterns unique to the individual and that they turn to such frequencies and patterns on subsequent treatment sessions. Pulse frequencies and pulse patterns were not related to the cause and site of pain, a finding consistent with previous study in this laboratory. This observation, coupled with the large variability in pulse frequencies and pulse patterns used between individuals, implies that patients prefer such frequencies and patterns for reasons of comfort which may not be related to mechanisms specific to the pain system.

Adult↗
PubMed1985

Gonadotropin-releasing hormone pulses in third ventricular cerebrospinal fluid of ovariectomized rhesus monkeys: correlation with luteinizing hormone pulses.

Morphological evidence suggests that GnRH may be released into cerebrospinal fluid (CSF) of the third ventricle. Therefore, a method of cannulating the third ventricle of monkey brains was developed for the purpose of examining GnRH secretion in primates. A stainless steel guide cannula was stereotaxically implanted into the third ventricle of 14 ovariectomized rhesus monkeys. A Silastic cannula for collecting CSF was inserted via the guide cannula into the ventral portion of the ventricle, permitting repeated CSF sampling for long time periods from the same animal. One week to 6 months after cannulation, CSF was collected continuously for periods of 5-10 h at 2 different rates (480 and 120 microliter/h) from conscious monkeys seated in chairs. Samples were divided into 15-min fractions, and the GnRH concentration in each was determined by RIA. In contrast to most previous studies, third ventricular CSF was found to contain significant concentrations of GnRH. GnRH was detected in 40 of 50 collections. Concentrations ranged from less than 8 to greater than 800 pg/ml, a range similar to that observed in hypophyseal portal blood. Furthermore, fluctuations within individual collections indicated that GnRH was released in pulses. The mean GnRH pulse frequency during the higher rate of CSF withdrawal was 0.43 +/- 0.06 pulses/h (n = 31), while the mean pulse amplitude was 91 +/- 7 pg/ml (n = 64). Neither parameter was influenced by the rate of CSF removal, as frequency was 0.52 +/- 0.08 pulses/h (n = 19) and amplitude was 94 +/- 11 pg/ml (n = 82) during the lower collection rate. However, the CSF withdrawal rate had a profound influence on LH secretion. In 12 of 17 collections at the higher rate, LH levels plummeted to undetectable concentrations during the first 2 h of CSF exfusion and remained low throughout the collection period. Pituitary responsiveness was not reduced, as a GnRH bolus (0.25 or 2.5 micrograms) after 6 h of CSF removal elicited a dose-dependent stimulation of LH secretion. In contrast, a higher incidence of normal pulsatile LH secretion (12 of 19 collections) was observed when the CSF withdrawal rate was reduced. During these 12 collections, LH and GnRH pulses occurred at regular intervals and exhibited similar pulse frequencies (mean +/- SE, 0.76 +/- 0.07 and 0.67 +/- 0.09 pulses/h for LH and GnRH, respectively). Most GnRH and LH pulses were synchronized, as 86% of all GnRH pulses (43 of 50) were accompanied by a LH pulse.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Pulse, a PC-based graphics pulse sequence editor for NMR and MRI.

A flexible, personal computer (PC) based, screen-graphics oriented pulse sequence editor called PULSE has been developed for nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI). PULSE is used to set such NMR spectroscopic parameters as the delay and duration of rf transmit and receive gates, rf phase, sampling times, and such imaging parameters as rf pulse shape and gradient waveforms. The output of PULSE is a set of programs that can be loaded into a hardware pulse programmer. With PULSE, any desired NMR or MRI pulse sequence can be programmed quickly and easily.

Computer Graphics↗
PubMed1988

Forehead pulse oximetry compared with finger pulse oximetry and arterial blood gas measurement.

Usual monitoring sites for pulse oximetry involve the fingers, toes, ear lobe, and nasal septum. This study examined the performance of a forehead sensor compared with a finger sensor for the pulse oximeter and arterial blood gas (ABG) analysis. Ten healthy adult volunteers and 22 ventilator-dependent patients were studied. The arterial oxygen saturation detected by forehead pulse oximetry (SpO2) correlated well with finger SpO2 and arterial oxygen saturation (SaO2) determined by arterial blood gas analysis in the healthy volunteers. Forehead SpO2 in mechanically ventilated patients correlated well with finger SpO2 and SaO2 when heart rate detected by pulse oximeter differed less than 10% from apical heart rate. Factors that caused a difference in oximeter-detected heart rate and apical heart rate were extensive tissue edema, head movement, and difficulty securing good tape placement. This suggests that when signal strength is weak, causing poor pulse rate detection, there will also be problems associated with accurate SpO2. The forehead pulse oximeter sensor works well on healthy, well-oxygenated volunteers. Difficulty was experienced when applying and using the sensor on critically ill patients. The reliability of the forehead pulse oximeter sensor has not been established at low saturations.

Adolescent↗
PubMed1988

Sequential pulse defibrillation in humans: orthogonal sequential pulse defibrillation with epicardial electrodes.

A newly described sequential pulse technique, using four mesh electrodes positioned to approximate a true orthogonal system around the heart, was compared with a single pulse system using two of these same electrodes, which were located in positions that would be used for an automatic implantable defibrillator. The influence of electrode size was also assessed. The minimal energy necessary for defibrillation (defibrillation threshold) was determined intraoperatively in 21 volunteer patients undergoing accessory pathway ablation of Wolff-Parkinson-White syndrome. Ventricular fibrillation was induced with alternating current. Ten seconds after fibrillation onset defibrillation shocks were begun using either the single or the sequential pulse technique with stored voltage incremented until defibrillation was accomplished (defibrillation threshold). Selection of the use of a single or sequential pulse technique for the initial attempt was randomized. Defibrillation thresholds were determined in three groups of patients: 1) those with four small mesh electrodes (6 cm2), 2) those with two small and two large (13 cm2) mesh electrodes, and 3) those with four large mesh electrodes. In all cases, the average minimal energy needed for sequential pulse defibrillation was less than that required for single pulse defibrillation in the same patients with the same electrodes (four small, 24.8 +/- 24.7 J single versus 6.7 +/- 8.3 J sequential; two small plus two large, 11.4 +/- 15.0 J single versus 2.7 +/- 1.4 J sequential; four large, 8.1 +/- 5.3 J single versus 3.9 +/- 2.6 J sequential). Using the 6 cm2 electrodes for single pulse defibrillation energies delivered at greater than 45 J in two patients failed to defibrillate the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗